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PASSIVE VENTILATION FOR PATIENT THERMAL COMFORT
1 K.H Hospital,Machakos. K. KITHOME:ABS211-0220/2017
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“It’s possible to have good ventilation in a building if you use the way nature works.”- Swedish architect, Anders Nyquist
2021
Kelvin Kithome
ABS211-0220/2017
Department of Architecture
School of Architecture and
Building Sciences
Jkuat
“A BREATHING HOSPITAL DESIGN”
Koma hills hospital

NZIOKA KELVIN KITHOME
ABS211-0220/2017
Submitted in partial fulfillment of the requirements for the Degree of Bachelor of Architectural Studies
At
JOMO KENYATTA UNIVERSITY OF AGRICULTURE AND TECHNOLOGY
SCHOOL OF ARCHITECTURE AND BUILDING SCIENCES
DEPARTMENT OF ARCHITECTURE
September 2021

DECLARATION
I declare that this is my original work. I hereby affirm that all information in this document has been obtained and presented in accordance with academic rules and ethical conduct. I also declare that, as required by
these rules and conduct, I have fully cited and referenced all material and results that are original to this work.
I firmly declare that to the best of my knowledge, this report proposal has not been presented to this or to any other university for examination or for any other purposes. This work forms part fulfilment of the
requirements for the award of the degree of Bachelor of Architectural Technology of Jomo Kenyatta University of Agriculture and Technology.
Signature………………………………………………………………... Date………………………………………………
Nzioka K. Kithome, B. Arch IV, 2021 (Author)
Signature………………………………………………………………... Date……………………………………………….
Arch.Misiani, B. Arch (Hons.) JKUAT, M.A.A.K (A) (Supervisor)
Signature………………………………………………………………… Date……………………………………………….
Arch. Hashim Nadi Omar, B. Arch (Hons.) JKUAT, M.A.A.K (A) (Chairperson, Department of Architecture)

ACKNOWLEDGEMENTS
I wish to thank my lectures Arch.Dr. Susan Kibue, Arch. Achera Misiani, Arch. Rita Mugo, Arch. Shikuku James, Arch. Nicholas Onyango and Arch.Marylyn Musyimi whose efforts, expertise and dedication to see
me through this project I will forever be grateful.
I affectionately dedicate this report to my loving parents, my family, and fellow colleagues.
I dedicate this work to the Almighty God, the greatest architect, for His overseeing and protection through it all.
DEDICATION
My parents, whose support and encouragement is second to none.

ABSTRACT
“A hospital must cause neither human nor ecological harm.” (S. Verderber,2010). Central to this, healthcare centers must integrate the medical process of healing with the environmental design considerations to
achieve a complete state of healing. Particular to this study, passive ventilation designs must be based principally on human comfort factors. “We pay enormous attention to the five main sensory organs in our bodies,
yet we often overlook our true sixth sense, thermal sensitivity.” –Andrew Marsh Ph. D, B.Arch.(Hon).
In light of this study, it aims at contributing to our knowledge of how designing a hospital that can trap wind movement and use it for ventilation without the use of mechanical techniques can cause a cool indoor
climate, good ventilation and a natural airflow in the building.
This study therefore proposes the application of the passive ventilation techniques to achieve a thermal comfortable environment in a community hospital. In addition, the incorporate of concepts of sustainable design,
accessibility, connectivity to outside, operability and community authenticity is key.
INSPIRATION
“Homeostasis (thermal regulation) is essential for the maintenance of health and its breakdown results in diseases.” –Faculty of Health Sciences University of Sidney
“Ventilation is the profound secret of existence.” –Peter Sloterdijk
Environmental design as the process of addressing the surrounding environmental
parameters e.g. geography, planning, landscape architecture and sustainability. Vital
principles to be incorporated in hospital design.Source:Author,2021
Incorporation of passive ventilation techniques in the hospital
design. Source:Author,2021
Above figures shows the visual inspirations behind a thermal
comfort hospital design concept
Courtyards, nature connectivity,
planning and orientation
Enhanced community interaction design.
Malqafs, wind catchers, openings,
roof design, louvers, wind towers,
Wind chimneys, open courtyards
Thermal comfort in
“A breathing hospital
design”
Koma hills
hospital

TABLE OF CONTENTS
Contents
DECLARATION .............................................................................................................................................................................................................................................................................................................................................3
ACKNOWLEDGEMENTS..............................................................................................................................................................................................................................................................................................................................4
DEDICATION.................................................................................................................................................................................................................................................................................................................................................4
ABSTRACT.....................................................................................................................................................................................................................................................................................................................................................5
INTRODUCTION ........................................................................................................................................................................................................9
1.0 BACKGROUND INFORMATION ......................................................................................................................................................................................................................................................................................................................................9
1.1 PROBLEM STATEMENT....................................................................................................................................................................................................................................................................................................................................................9
1.2 STUDY JUSTIFICATION....................................................................................................................................................................................................................................................................................................................................................9
1.3 STUDY OBJECTIVES .........................................................................................................................................................................................................................................................................................................................................................9
1.3.1 GENERAL OBJECTIVE ...............................................................................................................................................................................................................................................................................................................................................9
1.3.2 SPECIFIC OBJECTIVE.................................................................................................................................................................................................................................................................................................................................................9
1.4 DEFINITION OF TERMS ..................................................................................................................................................................................................................................................................................................................................................10
1.5 STUDY ASSUMPTION .....................................................................................................................................................................................................................................................................................................................................................10
1.6 STUDY SCOPE ..................................................................................................................................................................................................................................................................................................................................................................10
1.6.1 GEOGRAPHICAL.......................................................................................................................................................................................................................................................................................................................................................10
1.6.2 THEORITICAL SCOPE ..............................................................................................................................................................................................................................................................................................................................................10
1.6.3 METHODOLOGICAL.................................................................................................................................................................................................................................................................................................................................................10
1.7 STUDY LIMITATIONS .....................................................................................................................................................................................................................................................................................................................................................10
1.8 STUDY ORGANIZATION.................................................................................................................................................................................................................................................................................................................................................11
LITERATURE REVIEW .................................................................................................................................................................................................. 12
2.0 INTRODUCTION...............................................................................................................................................................................................................................................................................................................................................................12
2.1 PASSIVE VENTILATION ........................................................................................................................................................................................................................................................................................................................................................12
2.2.1 Stack pressure .........................................................................................................................................................................................................................................................................................................................................................12
2.2.2Wind pressure..................................................................................................................................................................................................................................................................................................................................................................13
2.3 CROSS VENTILATION ................................................................................................................................................................................................................................................................................................................... 14
2.4 CONVECTIVE VENTILATION..................................................................................................................................................................................................................................................................................................................................................15
2.5 AIR CIRCULATION AND MIXING...........................................................................................................................................................................................................................................................................................................................................15
2.6 DIRECTING WIND INTO HOSPITALBUILDING .......................................................................................................................................................................................................................................................................................................................16
2.7 NARROW HOUSE DESIGN ....................................................................................................................................................................................................................................................................................................................................................17
2.8 OPENINGS............................................................................................................................................................................................................................................................................................................................................................................18

2.9 MALQAF...............................................................................................................................................................................................................................................................................................................................................................................18
2.10 WIND TOWER ....................................................................................................................................................................................................................................................................................................................................................................20
2.11 THE VENTURI EFFECT:........................................................................................................................................................................................................................................................................................................................................................21
2.13 SOLAR CHIMNEY ................................................................................................................................................................................................................................................................................................................................................................23
2.14 THE ASHRAE METHOD.......................................................................................................................................................................................................................................................................................................................................................24
2.15 HEATING, VENTILATION AND AIR CONDITIONING SYSTEMS (HVAC) ................................................................................................................................................................................................................................................................................25
METHODOLOGY ........................................................................................................................................................................................................................................................................................................................................ 26
3.0 INTRODUCTION...............................................................................................................................................................................................................................................................................................................................................................26
3.1 RESEARCH METHODS..................................................................................................................................................................................................................................................................................................................................................26
3.2SOURCES OF DATA.........................................................................................................................................................................................................................................................................................................................................................26
3.3 SAMPLING........................................................................................................................................................................................................................................................................................................................................................................27
4.0 CASE STUDIES ...................................................................................................................................................................................................... 28
4.1INTRODUCTION................................................................................................................................................................................................................................................................................................................................................................28
4.1.1 Local case: Jkuat community hospital-KENYA ..................................................................................................................................................................................................................................................................................................................28
4.1.2 PASSIVE VENTILATION TECHNIQUES ATTEMPTED IN JKUAT HOSPITAL............................................................................................................................................................................................................................. 28
4.2 Local case: Startup lions –Turkana, KENYA.........................................................................................................................................................................................................................................................................................................................32
4.3 INTERNATIONAL CASE: Maternity village-MALAWI ..................................................................................................................................................................................................................................................................................... 33
4.3.1 PASSIVE VENTILATION DESIGN FOR THERMAL COMFORT AND BUILDING FORM....................................................................................................................................................................................................................................... 33
5.0 SITE DOCUMENTATION................................................................................................................................................................................................ 35
5.1 GENERAL SITE CONTEXT ......................................................................................................................................................................................................................................................................................................................................................35
5.2 GENERAL SITE CONTEXT ......................................................................................................................................................................................................................................................................................................................................................36
5.3 PHYSICAL DATA; CLIMATE ...................................................................................................................................................................................................................................................................................................................................................37
6.1 ENVIRONMENTAL FACTORS ....................................................................................................................................................................................................................................................................................................................... 38
7.0 BRIEF ANALYSIS...................................................................................................................................................................................................................................................................................................................................................................44
8.0 CONCEPT ANALYSIS .............................................................................................................................................................................................................................................................................................................................................................47
8.1 ABSTRACTION OF THE TERMITE MOUND ..........................................................................................................................................................................................................................................................................................................................49
9.0 OUTLINE DESIGN ................................................................................................................................................................................................................................................................................................................................................................50
10.0 FINDINGS,CONCLUSIONS AND RECOMMENDATION .......................................................................................................................................................................................................... 52
10.1 INTRODUCTION..................................................................................................................................................................................................................................................................................................................................................................52
10.2 Findings and conclusions....................................................................................................................................................................................................................................................................................................................................................52
10.2.1 Passive ventilation ..........................................................................................................................................................................................................................................................................................................................................................52
10.3 Recommendations .............................................................................................................................................................................................................................................................................................................................................................52
10.4 The application of recommendations in community hospital design ...............................................................................................................................................................................................................................................................................52
10.4.1 USE OF MALQAF IN THE COMMUNITY HOSPITAL.............................................................................................................................................................................................................................................................................................53
10.4.2 COMMUNITY HOSPITAL DESIGN.....................................................................................................................................................................................................................................................................................................................................53

PLANNING, ELEVATION, SECTIONS,.......................................................................................................................................................................................................................................................................................................................................54
10.4.3 VENTILATION DETAILS FOR THERMAL COMFORT .........................................................................................................................................................................................................................................................................................................55
10.4.6 INTERIOR DESIGN FOR THERMAL COMFORT .......................................................................................................................................................................................................................................................................................... 56
Summary....................................................................................................................................................................................................................................................................................................................................................................................59
PASSIVE VENTILATION FOR PATIENT THERMAL COMFORT................................................................................................................................................................................................................................................................................ 59
Recommendation appraisal tables...........................................................................................................................................................................................................................................................................................................................................61
Annex: sketches attachment............................................................................................................................................................................................................................................................................................................. 63
List of figures
Figure 1.1 image showing stack pressure, source: Author,2021...................................................................................................................................................................................................................................................................................................13
Figure 2.1: image showing wind pressure, source: Author,2021 ..................................................................................................................................................................................................................................................................................................14
Figure 3.1: image showing convective ventilation, source: Author, 2021....................................................................................................................................................................................................................................................................................15
Figure 4.1: image showing air circulation and obstruction effects, source: Author ,2021...........................................................................................................................................................................................................................................................16
Figure 5.1 : image showing louvers redirecting wind
Figure 6.1 : image showing various ways to redirect wind in a building, source: Author ,2021 ...................................................................................................................................................................................................................................................17
Figure 7.1: stack ventilation illustration, source: Author,2021 .....................................................................................................................................................................................................................................................................................................18
Figure 8.1 :image showing malqaf functioning, source: Author,2021...........................................................................................................................................................................................................................................................................................19
Figure 9.1: wind tower image, source: Author,2021.....................................................................................................................................................................................................................................................................................................................20
Figure 10.1: venturi principle, source: Author ,2021.....................................................................................................................................................................................................................................................................................................................21
Figure 11.1: Bernoulli’s principle, pressure difference, source: Author,2021...............................................................................................................................................................................................................................................................................22
Figure 12.1: solar chimney image, source: Author,2021...............................................................................................................................................................................................................................................................................................................23
List of tables
Table 1............................................................................................................................................................................................................................................................................................................................................................................................61

INTRODUCTION
1.0 BACKGROUND INFORMATION
Ventilation is the process of replacing air in any space to provide high indoor air quality I.e. to control temperature, replenish oxygen, or remove moisture, doors, smoke, heat, dust airborne bacteria and carbon
dioxide, (www.Wikipedia.org)Ventilation is used to remove unpleasant smells and excessive moisture, introduce outside air, to keep interior building air circulating, and also to prevent stagnation of the interior air.
This study will mainly focus on Natural ventilation for community hospital, which is majorly influenced by the building type, size, form and climate of the site idling account for about 40% of the energy consumption
in most developed countries and this consumption produces enormous emissions of CO2 which course indoor pollutants and lead to sick building syndrome that affect health and comfort of building occupants. (Evans,
1980)
Recent research indicates that pollutant concentration levels in the air inside buildings may be 2 to 5 times higher than the air outside and as people spend 75 to 90% of their time indoors, the quality of indoor air is an
issue of major concern. (Bay 1st end.2006)
1.1 PROBLEM STATEMENT
With the rise of global warming in the world, solution to thermal comfort is mainly by the application of mechanical techniques which consumes more energy. In addition, it is reported that many people have
complained of symptoms associated with acute discomfort, e.g., eye or throat irritation due to dryness of the air, headache, dizziness and nausea after spending sometime in a building with mechanical ventilations
systems in the recent years. Investigations showed that these effects are caused by polluted air containing chemicals used in construction materials or furniture, or combustion gas generated by equipment (Ghiaus,
1998). These design faults and lack of clear practical guidelines creates a gap, especially in hospital facility design, as there is need to develop models that foster thermal comfort through passive ventilation designs that
will aid in the recovery process of patients at the same time maximizing staff performances .This study therefore will attempt to bridge the gap between existing literature on passive ventilation design and practice of
architecture and building science in the design of a community hospital.
1.2 STUDY JUSTIFICATION
Saunders (2002) argues that unhealthy, indoor environments are a social and political rather than a psychological or physical issue. Using the allegory of the "boiled frog syndrome", he claims that humans in their
quest for greater comforts are creating ever unhealthier environments in their day to day life. The rejuvenation of a building's passive climate control features minimizes the need for mechanical aid, reduces energy
consumption, lowers maintenance expenses, and makes building more sustainable (Toledo, Francize 1999)
With health care sector being a fundamental need in the community, designing hospitals that enhances the patient’s comfort is vital. This will not only satisfy their need for a hospital but also aid in achieving their
complete state of healing. This study therefore, aims at analyzing passive ventilation and its role in creating a healthy indoor climate, a good indoor air quality, and its influence on thermal comfort in a community
hospital.
1.3 STUDY OBJECTIVES
1.3.1 GENERAL OBJECTIVE
To determine how passive ventilation as a design in hospitals can be applied to enhance a healthy, cool in-door climate and thermal comfort to patients.
1.3.2 SPECIFIC OBJECTIVE
CHAPTER
1

• To identify the different passive ventilation techniques and determine their appropriateness in solving thermal stress.
• To determine the role of passive ventilation in achieve a good and healthy indoor climate.
• To illustrate how the findings can be applied in Kantafu area to come up with a community hospital that enhance patient thermal comfort.
1.4 DEFINITION OF TERMS
1.4.1 THEORETICAL DEFINITIONS
• Natural Ventilation: A ventilation system that makes use of natural forces, such as wind and thermal buoyancy to circulate air to and from an indoor space, (Jennifer ,2002).
• Thermal comfort- is defined as: ‘that condition of mind which expresses satisfaction with the thermal environment’ (Bragger, Gail 1998).
• Space- space is defined as containers to accommodate, separate, structure and organize, facilitate, heighten and even celebrate spatial behavior. Space creates settings which organize our lives, activities and
relationships (Lawson, 2005).
1.4.2 OPERATIONAL DEFINITIONS
The following parameters will be used to clarify the objectives;
• Temperature- measured in degree Celsius
• (C02) Volume- measured in cubic metre (M3
)
• Area- measured in square metre (M2
)
1.5 STUDY ASSUMPTION
That the effect of thermal heat is the same to all the users.
That there is little consideration on design for passive ventilation.
1.6 STUDY SCOPE
1.6.1 GEOGRAPHICAL
The scope of the research is limited to the Kaza Wando, Kantafu area of Machakos, off Kangundo road and its close environs.
1.6.2 THEORITICAL SCOPE
The study remains in the confines of passive ventilation and its relation to thermal comfort of patients in a hospital.
1.6.3 METHODOLOGICAL
Sketches and illustrations will be used in order to show how various passive ventilation techniques are used to bring out the different concepts of planning and a thermal comfort design. Use of photographs to show
works of architecture that show passive ventilation techniques for a thermal comfortable environment will also be included.
1.7 STUDY LIMITATIONS
1) Very little architectural research information has been documented for this area, so there was vigorous search for problems either through interviews or photography will be the most appropriate way of gathering
information. This because the author relies a lot on cooperation of the respondents and their willingness to access their place of work.

2) Little time was allocated to carry out such an extensive research that requires a lot of input and space interrogation.
1.8 STUDY ORGANIZATION
Chapter one identifies the problem and place of research into context. It also states the objective of the study, scope, justification and limitations. It will also introduce the research methodology used to collect data in
the research.
Chapter two provides the literature review during the research from relevant publications and research
Chapter three analyzes research methodologies and their application.
Chapter four considers field surveys of selected case studies to provide more concise practical based information on the subject of study. Comparative tables and other data presentation techniques are included
showing how various case studies have attempted to deal with related issues.
Chapter five critically documents the forces on site and analyses them providing possible design interventions. It includes a comprehensive research into context, close neighborhood as well as on site elements
involving the people and the place. It also provides an analysis of the brief through exploration of the accommodation schedule in tabulated form.
Chapter six carries the conclusions and recommendations from the study. These are related to the ultimate objective of the study and provide possible design interventions to be used in the design phase.
Chapter seven will involve the concept formulation based on the research proposal topic. These deduced ideas will aid in propelling the overall design.
The report closes with a bibliography and appendices

LITERATURE REVIEW
2.0 INTRODUCTION
2.1 PASSIVE VENTILATION
Building and medical scientists have turned their attention to modern-day phenomena, such as sick-building syndrome (SBS), a controversial condition most often associated with artificially ventilated office
buildings, (Clements Croome 2000, Kroeling 1988, Warlock et al 2002).
The Literature review will be mainly based on the objectives of study which are: to identify various ways through which natural ventilation can be achieved in hospital design and maintain a thermally comfortable
indoor environment. A few generally accepted rules and codes are available to assist the designer in the task of dimensioning and control of natural ventilation systems. This could be achieved through properly
dimensioned, constructed and located window and shaft systems while responding to specific geometrical configurations and climatic situation of the buildings as well as to health and comfort related occupancy
requirements. (Niren L; 1993)
What is natural ventilation?
Natural forces (e.g. winds and thermal buoyancy force due to indoor and outdoor air density differences) drive outdoor air through purpose-built, building envelope openings. Purpose-built openings include windows,
doors, solar chimneys, wind towers and malqafs. This natural ventilation of buildings depends on climate, building design and human behavior, (WHO, 2007)
2.2 PASSIVE VENTILATION IN HOSPITAL
Comfort ventilation brings outdoor air into the building especially during the day when the temperatures are at their highest above 280
C. The air is then passed directly over people to increase evaporative cooling on the
skin. (Randall T; 1996) The general purpose of ventilation in buildings is to provide healthy air for breathing by both diluting the pollutants originating in the building and removing the pollutants. (James A, WHO,
2009). Before designing a purely natural ventilation system, designers need to understand the main driving forces of natural ventilation.
Natural forces control how air moves within and through a building, and they can be combined, as needed, to design an optimal natural ventilation system for a building. There are three main forces that can move air
into a building:
• Stack pressure
• Wind pressure
• Mechanical force
For the sake of this study, we shall consider wind pressure and stack effect as they are related to natural forces. However, these forces are variable and less easy to control than the forces associated with mechanical
forces, (Randall T, 1996).
Comfort ventilation brings outdoor air into the building especially during the day when the temperatures are at their highest above 280
C. The air is then passed directly over people to increase evaporative cooling on the
skin. (Randall T; 1996) The general purpose of ventilation in buildings is to provide healthy air for breathing by both diluting the pollutants originating in the building and removing the pollutants. (James A, WHO,
2009). Before designing a purely natural ventilation system, designers need to understand the main driving forces of natural ventilation.
2.2.1 Stack pressure
It is mainly generated from the air temperature or humidity difference between indoor and outdoor air. When the interior air temperature T1 of the room is warmer than the outside air temperature T0, the room air is
less dense hence rises.
CHAPTER
2

Figure 1.1 image showing stack pressure, source: Author,2021
Air simply flow from one opening to another as wind is driven through cross ventilation, through windows placed on opposite external walls is relatively easy to achieve. Air enters the room through lower openings
and escapes through upper openings. The airflow within the room reverses when the room is colder than the air outside air; the room air is denser than the outside air. Air enters the building through the upper openings
through the lower openings.
When wall ventilation is not sufficient enough due to low air velocity roof ventilation can be added, based on Bernoulli Principle and Venturi effect that induces air to be sucked out of the roof opening at the ridge
(Francus A, Mateous S,1998).
2.2.2Wind pressure
Wind has two sides, the positive pressure and negative pressure. Air moves from an area of high pressure to an area of low pressure, (www.lighting canyon.com; 28-11-21). This difference generates imbalance in the
pressure gradients of the interior and exterior air columns, causing vertical air pressure difference.
Wind strikes a building creating positive pressure on the windward face which is about 0.5-0.8 times the wind pressure. And negative pressure on the windward side which is about 0.3-0.4 times the wind pressure
These drives airflow through the windward openings such as windows and doors into the building to the low pressure openings at the leeward face hence air movement within the internal spaces of a room, (Randall T;
1996)

A - Wind blowing towards a surface exerts a positive pressure over it.
B - As the wind hits the surface the air stream splits and moves around the sides of obstruction.
C - Leeward side, wind blowing away from the surface exerts negative pressure, air pulls away from the obstruction and this causes sanction, this sucks out air from the openings behind it.
Figure 2.1: image showing wind pressure, source: Author,2021
2.3 CROSS VENTILATION
It is the most effective passive ventilation mechanism. It basically occurs where there are pressure differences between one side of a building and the other. Typically, this is a wind-driven effect in which air is drawn
into the building on the high pressure windward side and is drawn out of the building on the low pressure leeward side.

Wind can also drive single-sided ventilation and vertical ventilation, (https://www.designing buildings.co. up/wiki Nov 2021). It is advisable not to place openings exactly across each other, while it gives effective
ventilation, it can cause some of the spaces of the room not to be well ventilated. Placement of openings across and not opposite each other allows air mixing, distributing the cooling and fresh air.
2.4 CONVECTIVE VENTILATION
Convective ventilation can work without breezes- as long as there are temperature differences between indoor and outdoor air. One can increase cross ventilation by having larger openings on the leeward face of the
building that the windward faces and placing inlets at higher pressure zones and outlets at low pressure zones. However, that will not be effective unless the differences are sufficiently high.
The temperature differences between T0 and T1 of more than 400
C will trigger noticeable effect. The body however experiences a thermal comfort range of 250
C to 280
C, (Ahmad S, Mahyuddin R; 2010). Therefore,
during the connective ventilation process, it is important to ensure that this temperature is not exceeded
Figure 3.1: image showing convective ventilation, source: Author, 2021
2.5 AIR CIRCULATION AND MIXING
Openings between rooms should be considered carefully in naturally ventilation strategies to enhance thermal comfort. Transom windows, grills, canopies and louvers are important elements to complete the air circuit
through the hospital design. To maximize the air mixing, orientation of windows, and their spacing from each other is fundamental. Reduction of the level of obstruction between the rooms also assist in the overall
airflow within a given room.

Exhaust openings should be located high enough, to maximize convective cooling. Ventilation moves outdoor air into a building or a room, and distributes the air within the space. It is important to note that for natural
ventilation to occur, great considerations should be taken on the general airflow direction and also the site configuration. When developing the design concept for the naturally ventilated hospital to enhance thermal
comfort and indoor air quality, there are three basic steps: -
1.Specify the desired airflow pattern from the inlet openings to the outlet openings.
2.Identify the main available driving forces that allow the desired airflow pattern to be achieved for optimal comfort.
3.Size and the location of the openings so that the required ventilation rates by the occupants can be delivered under all operating inlets.
Figure 4.1: image showing air circulation and obstruction effects, source: Author ,2021
2.6 DIRECTING WIND INTO HOSPITALBUILDING
The outdoor air that is cooler than indoor air, can be directed into the hospital through various ways. The wind may be directed either upwards or downwards. Positioning of elements like louvers and canopies can be
used to control the way the wind is directed into the spaces. Air inflow direction is important within a living space in hospitals example wards, since the users are able to adjust the amount and direction of air entering
the space.
Canopy can be placed over a window and this will direct the air upwards. Moving air can also be directed upwards by positioning the angle of the louver windows.
For downward direction of the moving air, two methods are discussed below. A canopy that has a gap between it and the wall can be placed above the window and this will make the breezes to gain a downward
direction as illustrated.
Breezes can also be directed by the angled positioning of the louver windows. Wind can also be steered by architectural features such as casement windows, wing walls, fences or even strategically planned vegetation.
Wing walls project outwards next to a window, so that even a slight breeze against the wall creates a high pressure zone on the side and low on the other. The pressure difference draws outdoor air in through one open
window and out the adjacent one as illustrated.

Figure 5.1 : image showing louvers redirecting wind
Figure 6.1 : image showing various ways to redirect wind in a building, source: Author ,2021
2.7 NARROW HOUSE DESIGN
Venturi Effect involves the reduction of fluid pressure (wind), resulting in when a fluid flows through a constricted section or a narrow space. The velocity of a fluid increases as the cross-sectional area decreases,
causing the pressure to also decreases. (www.pipe calculations.com, 28/11/2021). This is applied in room situations as a narrow room described as it length to width ratio having a minimum of 1 to 2 with the openings
at a shorter length. (See figure below)
In hot climates, a narrow and relatively small space will be much easier to cool with natural ventilation. In areas of hot climate, a narrow building with an open floor design without obstructions make natural ventilation
more efficient.
Bernoulli Principle which states that for any viscid flow an increase in the speed of fluids occur simultaneously with a decrease in pressure, (Hubert,2004). In a wide room design, given its minimum length to width
ratio is about 2 to 1, as air flows into the space, its velocity reduces leading to increased wind pressure into the room. Having a greater indoor wind pressure than the outdoor wind pressure impends air outflow from the
space.
Stack Ventilation, just as Bernoulli principle, uses air pressure differences due to height to pull air through the building, lower pressure higher in the building help pull the air up as illustrated in figure 2.7

Figure 7.1: stack ventilation illustration, source: Author,2021
2.8 OPENINGS
Various types of window openings have different effects on the wind inflow into a room. It can either occur when a window is fully open and if not, vents can be placed within the window to permit infiltration of air
even if the window is closed. For natural ventilation purposes, preference goes to casement windows and louvers to other types of windows.
Louvers and casement windows can deflect the breezes when the air patterns are not promising for channeling the wind into the supply openings. Infiltration that occurs mainly depends on the type and quality of
construction and sizes of the window.
2.8.1 UPPER OPENINGS: Upper openings involve roof vents, clerestories, solar chimneys and other upper convection pathways. All of them can be excellent for expelling hotter air but they may collide with other
goals, namely the building sealing and insulation in temperature and cold climates. Roof ridge and vents are ideal of convective ventilation in hotter climates.
Wind tower see figure alongside permits air into the room through the roof vent.
Stack flue involves placement of a covered flue similar to a fireplace chimney drives the indoor air upwards,
2.8.2 INTERIOR OPENINGS: Interior doors must not block the convective airflow and air circulation. High louvers and other openings between the rooms, should be considered for better air circulation. Breezes can also
be directed into the internal spaces through the use of louvers and canopies.
Natural ventilation is based on fresh air entering through openings in the walls (on the windward side of the hospital building). That fresh air aids in getting warmer air out of the building through the other side via
cross ventilation and through the roof vents or other upper openings.
2.9 MALQAF
Malqaf use is one of the external air trapping techniques commonly used in hot and dry regions, arid zones. The technique is based on the concept of increasing air speed around the human body. Increasing the air
speed causes heat loss and a higher evaporation rate delivering direct physiological cooling effect which leads to more comfort.

The idea of a malqaf is trapping the wind from the higher parts of the building where air is not close to the ground surface and thus not carrying much sand and dust. This is due to the fact that dust is dense thus higher
in quantity on the low blowing winds. The Malqaf mainly serves the following purposes:
1. Providing air circulation and replacement.
2. Providing convective cooling.
3. Providing evaporative cooling.
Figure 8.1 :image showing malqaf functioning, source: Author,2021
2..9.1 MALQAF POSITIONING
The idea of a malqaf is trapping the wind from the higher parts of the building where air is not close to the ground surface and thus not carrying much sand and dust. It could also be located in combination with a
courtyard on the windward side. The Malqaf mainly serves the following purposes:
1. Providing air circulation and replacement.

2. Providing convective cooling.
3. Providing evaporative cooling.
To improve the efficiency of a malqaf, wet charcoal is used to trap the dust particles and also moisten the dry air thus providing a cool sensation to the users of the space.
2.10 WIND TOWER
A wind tower type of natural ventilation system can capture the wind at roof level and direct it down to the rest of the building (see Figures 2.9). Weatherproof louvres are installed to protect the interior of the building
and volume control dampers are used to moderate flow. Stale air is extracted on the leeward side. The wind tower is normally divided into four quadrants, which can run the full length of the building and become air
intakes or extractors depending on wind direction.
Figure 9.1: wind tower image, source: Author,2021

2.11 THE VENTURI EFFECT:
The venturi effect is a physical phenomenon of the flow of fluids. This is created by a fluid natural tendency to equalize pressure across two or more zones.
The venturi effect is utilized by buildings for natural ventilation and passive cooling. The purposeful creation of positive and negative air pressure zones can create an increased air flow through a building or across a
surface creating a cool effect. This cooling of surfaces helps reduce the amount of conductive energy in a material that can in turn remove cool air from the interior of the building.
A building's position and orientation in relation to predominant wind direction can create predictable zones of positive and negative air pressure, (See figure 2.10). This understanding allows the designer to thoughtfully
place swinging doors on the low or negative pressure side of the building, typically the leeward side of the building, thus reducing the occurrence of difficult doors that do not want to open due to pressure differences.
The Venturi effect in a building is also achieved by allowing the wind to partially enter the building through the roof thus creating a vacuum effect which pulls the hot stale air with more effectiveness out of the
building.
A building's position and orientation in relation to predominant wind direction can create predictable zones of positive and negative air pressure, (see figure 2.10). This understanding allows the designer to thoughtfully
place swinging doors on the low or negative pressure side of the building, typically the leeward side of the building, thus reducing the occurrence of difficult doors that do not want to open due to pressure differences.
The Venturi effect in a building is also achieved by allowing the wind to partially enter the building through the roof thus creating a vacuum effect which pulls the hot stale air with more effectiveness out of the
building.
Figure 10.1: venturi principle, source: Author ,2021

2.12 BERNOULLI PRINCIPLE
Bernoulli's principle uses wind speed differences to move air. It is a general principle of fluid dynamics, saying that the faster the air moves, the lower its pressure. (See figure 2.11). Architecturally, outdoor air further
from ground is less obstructed, so it moves faster than the lower air, and thus has lower pressure. This lower pressure can help suck fresh air through the building. A building's surrounding can greatly affect this
strategy by causing more or less obstruction. The advantage of Bernoulli's principle over stack effect is that it multiplies the effectiveness of wind ventilation. The advantage of stack ventilation over Bernoulli's
principle is that it does not need for wind; it works just well on still, calm days. A simple chimney optimizes for the stack effect, while wind scoops optimize for Bernoulli's principle.
A good example is the specially-designed wind cowls in the Bed ZED development, manipulates the faster winds above rooftops for passive ventilation. They have both intake and outlet, so that fast rooftop winds get
scooped into the buildings, and the larger outlets create lower pressures to naturally suck air out. The stack effect also helps pull air out through the same exhaust vent.
To best design for this effect, an important consideration is to have a large difference in height between the air inlets and outlets. Towers and chimneys can be useful to carry air up and out, or skylights or clerestories in
more modest buildings. For these strategies to work, air must be able to flow between levels. Multi-story buildings should have vertical atria or shafts connecting the airflow of different flows.
Figure 11.1: Bernoulli’s principle, pressure difference, source: Author,2021

2.13 SOLAR CHIMNEY
A solar chimney is a type of passive solar heating and cooling system that can be used to regulate the temperature of a building as well as providing ventilation. Like a Trombe wall or solar wall, solar chimneys are a
way to achieve energy efficient building design. Solar chimneys are hollow containers that connect the inside part of the building to the outside part of the building.
Solar chimneys are generally tall, wide structures constructed, facing the sun, with a dark colored, matt surface designed to absorb solar radiation. As the chimney becomes hot, solar heat gain warms a column of air in
the chimney, which then rises, pulling new outside air through the building. (See figure 2.12). They are also called thermal chimneys, thermosiphons, or thermosiphons. This can be used to drive passive ventilation
in buildings where cross ventilation or stack ventilation may not be sufficient, Solar chimneys need their surfaces painted dark to absorb most heat, their exhaust also has to be higher than the roof level. They are
generally most effective for climates with a lot of sun and little wind; climates with more wind on hot days can usually get more ventilation using the wind itself.
Figure 12.1: solar chimney image, source: Author,2021

2.14 THE ASHRAE METHOD.
In this method, the free area of the inlet opening, A, in a building with equal inlet and outlet openings can be calculated with the following expression.
A = Q/ (EW)
Where Q is the design flow rate, W is the wind speed and E is the effectiveness of the opening. Parameter E should be taken as 0.6-0.6 for perpendicular winds and 0.250.35 for diagonal winds. Equation 1;
(Source ASHRAE standard 62-1981).
In this method, the greatest flow per unit area of openings is obtained when inlets and outlets size are equal. This formula may also be used when the inlet and the outlet area of openings are not equal to calculate the
minimum areas of openings. The final flow as a function of the ratio of the highest to the lowest of the openings.
To calculate the openings is, for a given ratio of inlet to outlet openings, the percentage of the flow increase, X. Then the designed airflow, Q, is divided by X, and the resulting flow is used in equation 2 below to
calculate the minimum area of openings. If the local wind speed is not important and the airflow is mainly due to the temperature difference between the indoor and the outdoor, ASHRAE proposes another formula to
calculate the area of openings. If the inlets and outlets are equal, then the surface of the inlet or outlet opening, A, can be calculated from the following equation:
A = Q [116 h (T1 - T0)] Equation 1;
(Source ASHRAE standard 62-1981).
Where h, is the height from inlets to outlets in metres,
T1 & T0 are the average indoor and outdoor temperatures in 0C.

2.15 HEATING, VENTILATION AND AIR CONDITIONING SYSTEMS (HVAC)
At times the wind speed is not adequate to adequately ventilate the spaces. At such critical moments automated HVAC systems may be used, temporarily. The purpose of HVAC is to provide and maintain a
comfortable state of environment within a building, for the comfort of the users.
2.15.1 HEATING, VENTILATION AND AIR CONDITIONING SYSTEMS (HVAC)
An HVAC system functions to provide an environment in which the following functions are maintained within the desired ranges:
1. 750F temperature for dry bulbs
2. 40-60% Relative Humidity
3. ASHRAE 62.1 - 2007//2010 Ventilation
17CFM Outside air per person
CO2 Less than 1000PPM
2.15.2 TEMERATURE CONTROL STRATEGIES:
• Vary the temperature of the supply air to the space while keeping the air flow rate constant. This is the constant volume, variable temperature approach.
• Vary the air flow rate while keeping the supply air temperature constant. This is the variable volume, constant temperature approach. VAV –variable air volume system.
• Vary the supply air temperature and the flow rate, as in a variable volume reheat system.
2.15.3 RELATIVE HUMIDITY CONTROL
• Humidification - The air is too dry and water vapor must be added for comfort.
• Dehumidification - The air is too wet and water vapor must be removed for comfort.
• AC systems typically over-cool the air to remove water vapor, and then may have to heat the air back up - this is called reheat, and requires additional energy.
2.15.4 PRIMARY EQUIPMENTS USED
• Chillers
• Direct expansion (DX) systems
• Boilers
• Furnaces
• Single duct, single zone system
• Single duct, terminal reheat system
• Multizone system
• Dual duct system

METHODOLOGY
3.0 INTRODUCTION
This topic deals with the research questions, research design, sources of data, sampling and methods used to collect data in the field. Each method is described and analyzed and the limitations of each stated. A logical
research method is recommended in order to deepen and widen the understanding of the topic and provide data, facts and necessary information necessary to understand all results.
3.1 RESEARCH METHODS
The research methods to be used include:
Library review
This includes reviewing similar or related works and studies done by other researchers. It also involves collection and reviewing of information from other written text and published books.
Comparative case study methods
This includes analysis of already existing projects related to the topic or research to be done. It involves analyzation of both local and international case studies. This method helps the researcher obtain information
from the cases which will enable the author be informed in areas such as; climate, regional factors, technology, in the cases.
Unstructured interviews
For ease of processing data and due to time constrains, simple questions were asked to the users as well as the management on areas the study deals with. Questions asked were informal in nature as the users went on
with their activities. Respondents were picked at random and expected to rate their experience within the spaces.
3.2SOURCES OF DATA
Both primary sources and secondary sources of data were used.
3.2.1 Primary sources of data
This is original data that was collected first hand by the author The researcher targeted users of the space and interviewed them to understand the conditions on site and get insight on an ideal “face” of the community
hospital that the proposed project is to address. The people targeted were mainly people who work there acting as the case study. Moreover, the observation technique was used to assess the spaces based on the
researcher’s prior knowledge.
3.2.2 Secondary sources of data
CHAPTER
3

This includes original data that was collected by someone else other than the researches. An intensive and thorough literature review sourced from books, journals and reliable websites was used to derive the secondary
data. Additionally, previous analysis on the chosen case studies were considered.
3.3 SAMPLING
Selection of case studies was based on the definition of “passive ventilation for thermal comfort”. It was also applied to select respondents who took part in the unstructured interviews mentioned above.
3.4 DATA COLLECTION
The following methods were used:
i) Literature review
As the first step, several literatures including books, articles, master theses and doctoral dissertations on the subject of thermal comfort and workable buildings as well as proposed and implemented technical solutions
were reviewed to gain an understanding about incorporation of and concepts of thermal comfort and how it can be achieved through passive ventilation techniques.
ii) Observation
This was useful in identify the flow of processes and activities within and without the site.
iii) Measurement
Involve the use of a measuring tape, scale ruler and other necessary measuring instruments to determine specific characteristics of buildings in relation to their sites in the local case studies.
iv) Note taking
Responses from the interviews written down.
v) Photographs
Photographs were used to record features that may have been left out during observation that would aid in data analysis.
vi) Sketches
Sketches were of particular use in areas where photography was restricted as it would cause discomfort to users of the space at that particular.
Raw data collected from the field was studied for errors and consistency. It was then compiled and the data compared in order to come up with conclusions based on the study findings.
3.5 RESEARCH DESIGN
The case study approach shall be used. This is relevant for the researcher to establish the likely problems to be encountered while designing the community hospital in Kantafu, Machakos.

4.0 CASE STUDIES
4.1INTRODUCTION
4.1.1 Local case: Jkuat community hospital-KENYA
4.1.2 PASSIVE VENTILATION TECHNIQUES ATTEMPTED IN JKUAT HOSPITAL
Figure 1 0-1
Local case: Jkuat community hospital-KENYA
CHAPTER
4

-KENYA
Figure 1

4.2 Local case: Startup lions –Turkana, KENYA
4.2.1 PASSIVE VENTILATION TECHNIQUES, THE SIGNIFICANT WIND TOWER IN START-UP LIONS CAMPUS

4.3 INTERNATIONAL CASE: Maternity village-MALAWI
4.3.1 PASSIVE VENTILATION DESIGN FOR THERMAL COMFORT AND BUILDING FORM

4.3.2 PASSIVE VENTILATION DESIGN FOR THERMAL COMFORT AND BUILDING PLANNING
Architect: A+r Architekten
Area :515M2

5.0 SITE DOCUMENTATION
5.1 GENERAL SITE CONTEXT
LOCATED IN MACHAKOS COUNTY –KENYA.
CHAPTER
5
KOMAROCK
PROPOSED SITE
-AREA OF
APPROXIMATELY
11,000M2
IMMEDIATE
NEIGHBOURHOOD
1, Kiamba primary school
2.AIC Komarock church
3, Koma market
4.Koma hills
IMAGES
PHOTOGRAPHY BY KITHOME
KOMAROCK PROPOSED
SITE
-AREA OF APPROXIMATELY
11,000M2
IMMEDIATE
NEIGHBOURHOOD
3, Koma market
4.Koma hills
COMMERCIAL SPACES
OFF KANGUNDO ROAD
11,000M2
IMMEDIATE
NEIGHBOURHOOD
3, Koma market
4.Koma hills
COMMERCIAL SPACES OF
KANGUNDO ROAD
11,000M2
COMMERCIAL SPACES
-HARDWARE STORE
IMMEDIATE
NEIGHBOURHOOD
3, Koma market
4.Koma hills

5.2 GENERAL SITE CONTEXT
Figure 1.1
KOMAROCK SITE
-AREA OF
APPROXIMATELY
11,000M2
IMMEDIATE
NEIGHBOURHOOD
3, Koma market
4.Koma hills
AIC KOMAROCK CHURCH
11,000M2
IMMEDIATE
NEIGHBOURHOOD
3, Koma market
4.Koma hills
KIAMBA PRIMARY SCHOOL
11,000M2
IMMEDIATE NEIGHBOURHOOD
3, Koma market
4.Koma hills
KOMARACK PLANTED FOREST
11,000M2
IMMEDIATE NEIGHBOURHOOD
COMMERCIAL SPACES OF
KANGUNDO ROAD
11,000M2
IMMEDIATE
NEIGHBOURHOOD
3, Koma market
4.Koma hills
IMAGES
PHOTOGRAPHY BY Kelvin Kithome(author)

5.3 PHYSICAL DATA; CLIMATE
KOMAROCK
PROPOSED SITE
-AREA OF
APPROXIMATELY
11,000M2
IMMEDIATE
NEIGHBOURHOOD
1, Kiamba primary
school
2.AIC Komarock
church
3, Koma market
4.Koma hills
WIND ANALYSIS
11,000M2
IMMEDIATE
NEIGHBOURHOOD
3, Koma market
4.Koma hills
WIND ANALYSIS
RAINFALL ANALYSIS
TEMPERATURE
SUN PATH
SUN PATH
11,000M2
IMMEDIATE
NEIGHBOURHOOD
3, Koma market
4.Koma hills
TEMPERATURE
11,000M2
IMMEDIATE
NEIGHBOURHOOD
3, Koma market
4.Koma hills

6.0 SITE ANALYSIS
6.1 ENVIRONMENTAL FACTORS
CHAPTER
6

ENVIRONMENTAL FACTORS
6.2 ENVIRONMENTAL FACTORS

6.3 SITE CHARACTER

7.0 BRIEF ANALYSIS CHAPTER
7

8.0 CONCEPT ANALYSIS CHAPTER
8

CONCEPT ANALYSIS
ABSTRACTION OF THE TERMITE MOUND

8.1 ABSTRACTION OF THE TERMITE MOUND

9.0 OUTLINE DESIGN
CHAPTER
9

9.1 CONCEPTUAL ELEVATIONS

10.0 FINDINGS,CONCLUSIONS AND RECOMMENDATION
10.1 INTRODUCTION
This chapter entails a conclusion of the whole research study in this thesis. A conclusion of all the objectives and the crucial points noted from this study. In addition,
recommendations of every objective are also stated in this chapter
10.2 Findings and conclusions
10.2.1 Passive ventilation
The research is based in Kenya, Machakos county which is a semi-arid region. Komarock, Machakos experiences hot days which makes thermal comfort a vital issue to tackle within the region. Moreover, hospital
designs in the region require the incorporation of passive design-natural ventilation strategies to enhance patients thermal comfort. This will not only create a healing environment but also a comfortable environment to
the community.
This study has therefore, established that passive ventilation is vital in enhancing a good thermally comfortable environment.
10.3 Recommendations
With passive ventilation design in mind the following should be adopted in order to achieve thermal comfort in Koma hills hospital.
1.Use of wind towers.
2.open, well shaded facades.
3.position of openings
4.type of openings in design
5.use of malqafs
6.use of solar chimneys
7.orientaion of building.
8.use of wind catching roofs.
9.open layout plan with minimal obstruction
10.4 The application of recommendations in community hospital design
CHAPTER
10

10.4.1 USE OF MALQAF IN THE COMMUNITY HOSPITAL
Malqaf use is one of the external air trapping techniques commonly used in hot and dry regions, arid zones. The technique is based on the concept of increasing air speed around the human body. Increasing the air
speed causes heat loss and a higher evaporation rate delivering direct physiological cooling effect which leads to more comfort.
The idea of a malqaf is trapping the wind from the higher parts of the building where air is not close to the ground surface and thus not carrying much sand and dust. This is due to the fact that dust is dense thus higher
in quantity on the low blowing winds. The Malqaf mainly serves the following purposes: 1. Providing air circulation and replacement. 2. Providing convective cooling. 3. Providing evaporative cooling.

10.4.2 COMMUNITY HOSPITAL DESIGN
PLANNING,
ELEVATION,
SECTIONS, SHOWING
APPLICATION OF
PASSIVE VENTILATION
FOR THERMAL
COMFORT.

10.4.3 VENTILATION DETAILS FOR THERMAL COMFORT

10.4.5 USE OF WIND TOWERS AND BRICK (HIGH THERMAL MASS )WALL FOR THERMAL COMFORT

10.4.6 INTERIOR DESIGN FOR THERMAL COMFORT

Summary
Passive ventilation is the process of supplying air to and removing air from an indoor space without using mechanical systems. It refers to the ﬂow of external air to an indoor space as a result of pressure differences
arising from natural forces. There are two types of natural ventilation occurring in buildings: wind driven ventilation and buoyancy-driven ventilation (https://en.wikipedia.org/w/index.php?
title=Passive_ventilation&oldid=997445721" 7/12/2021).
With health care sector being a fundamental need in the community, designing hospitals that enhances the patient’s comfort is vital. This will not only satisfy their need for a hospital but also aid in achieving their
complete state of healing. This study therefore, aims at analyzing passive ventilation and its role in creating a healthy indoor climate, a good indoor air quality, and its influence on thermal comfort in a community
hospital.

References
1.ASHRAE. Health care facilities. In: Handbook of HVAC applications. Atlanta, USA, American Society of Heating Refrigerating and Air-Conditioning Engineers Inc., 2007a.
2.ASHRAE. HVAC design manual for hospitals and clinics. Atlanta, USA, American Society of Heating Refrigerating and Air-Conditioning Engineers Inc., 2007b.
3.ASHRAE. ASHRAE handbook fundamentals. Atlanta, USA, American Society of Heating, Refrigerating and Air-Conditioning Engineers Inc., 2009.
4.Awbi HB. Ventilation of buildings, 2nd ed. New York, Taylor & Francis, 2003.
5.Etheridge D, Sandberg M. Building ventilation-theory and measurement. Chichester, UK, John Wiley & Sons, 1996.
6.Kroeling, P. (1988). “Health and well-being disorders in air-conditioned buildings; comparative investigations of the ‘Building Illness’ syndrome”. Energy and Buildings 11 (1-3): 277-282.
7.Holmberg, J. G., and T. Burt. 2000. Preventive conservation methods for historic buildings: Improving the indoor climate by changes to the building envelope. In Conservation Without Limits: IIC Nordic Group XV
Congress, August 23–26, 2000, Helsinki, Finland, ed. Riitta Koskivirta, 71–88. Loimaa: Loimaan.
8.Linden, P. F. (1999). "The Fluid Mechanics of Natural Ventilation". Annual Review of Fluid Mechanics. 31: 201–238. Bibcode:1999AnRFM...31...201L (https://ui.adsabs.harvard.edu/abs/1999AnRFM...31...201L).
doi: 10.1146/annurev.ﬂuid.31.1.201 (https://doi.org/10.1146%2Fannurev.ﬂuid.31.1.201).
9.Walker, Andy. "Natural Ventilation" (http://www.wbdg.org/resources/naturalventilation.php). National Institute of Building Sciences.
10.Wang, Haojie; Chen, Qingyan (2012). "A New Empirical Model for Predicting Single-Sided, Wind-Driven Natural Ventilation in Buildings". Energy and Buildings. 54: 386–394. doi: 10.1016/j.enbuild.2012.07.028
(https://doi.org/10.1016%2Fj.enbuild.2012.07.028).
11.Autodesk, 2012. Passive Heat Recovering Ventilation System. [Online] Available at: sustainabilityworkshop.autodesk.com/project-gallery/passive-heat-recovering-ventilationsystem
12."Ventive" (http://ventive.co.uk/). ventive.co.uk. Retrieved 2021-11-28.
13. Clancy, L.J. (1975). Aerodynamics. John Wiley & Sons.

Recommendation appraisal tables
Recommendation 1: To help achieve thermal comfort in hospitals, adequate ventilation in a health-care facility, in all patient-care areas, is necessary.
Population: Health-care settings
Intervention: Passive ventilation for thermal comfort.
Factor Decision Explanation
Table 1
Feasibility Conditional to country settings • Natural ventilation is less feasible in extreme climates
(extreme cold, hot, noisy, polluted).
Benefits or desired effects Strong (benefits sometimes outweigh disadvantage) • Suitable for mild or moderate climates.
• Lower capital, operational and maintenance costs.
• Capable of achieving very high ventilation rate.
• Easily affected by outdoor climate
Cost May be low or high • Low cost if simple ventilation techniques are used,
• High cost if high tech ventilation strategies are used.

Costs May be low and high
Low cost if simple ventilation is used and properly designed with suitable climate. Can be higher if hybrid (mixed-mode) ventilation or high-tech natural ventilation is u
ANNEXES
Annex: Basic concept of ventilation flow rate
The ventilation flow rate can be referred to as either an absolute ventilation flow rate in l/s or m3/s, or an air-change rate relative to the volume of the space. In this guideline, the ventilation rate is referred to as the absolute amount of inflow air
per unit time (litre per second or l/s, cubic meter per hour or m3/hr) and the air-change rate as the relative amount of inflow air per unit time. For instance, in an airborne infection isolation room, we need a 12 ACH air-change rate (CDC, 2005),
while in an office, we need a 10 l/s per person ventilation rate. The relationship between ventilation rate in l/s and air-change rate is:
Ventilation rate (l/s) = air-change rate × room volume (m3) × 1000 (l/m3)/3600 (s/hr) (C.2)

Annex: sketches attachment
Sketches attachment

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