Simon Keogh presents on ventilation in dwellings in the NZEB session at the SEAI Energy Show.

1. Ventilation in Dwellings
Simon Keogh
Senior Architect
John Doran
Senior Mechanical Engineer
Hayes Higgins Partnership
RIAI Sustainability Task Force

2. Overview
Part F Dwellings – New
1. New Regulations - 3 ventilation systems
1. MEV (Mechanical Extract Ventilation)
2. MVHR (Mechanical Ventilation Heat Recovery)
3. NV (Natural Ventilation) commonly known as ‘trickle vent’
2. Current NV challenges
3. Mechanical Systems
4. Impacts on Space
5. Wireless Sensor Networks – IAQ

3. Introduction - Current legislation
The Building Regulations TGD F 2018 DRAFT describes 3 main systems of ventilation:
Section Type AP (Air Permeability)
1.2.2 (c) Mechanical Extract Ventilation (MEV) < 3 m3/m2/hr
1.2.3 Mechanical Ventilation Heat Recovery
(MVHR)
< 3 m3/m2/hr
1.2.4 ‘Natural Ventilation’ (NV)
E = 7000 mm2 trickle vents to habitable
rooms PLUS
• total minimum 42,000mm2
• 7000 mm2/10sqm over 70sqm
• mechanical extract ventilation from wet
rooms
3- 5m3/m2/hr
Table 1
1.2.1 Other approaches may be adopted to meet Building Regs
(The Requirement F1)

4. Introduction - Current Legislation
Part F acknowledges that as the standard of air tightness increases in Part L ,
the holes in the walls need to get bigger by 40%
CONFLICT = The efficiency of air tightness is lost through additional ventilation

5. Introduction - Ventilation Purpose
Ventilation systems controls the quantity and quality of air passing through the dwelling
to control
1. Carbon Dioxide
2. Moisture and humidity
3. Draughts
4. Volatile Organic Compounds (VOC)
5. Carbon Monoxide
6. Smells and odours
7. Mould and bacteria
8. Noise
9. Dust and dirt
…OR just comfortable healthy buildings for Irish citizens

6. Natural Ventilation (NV) – a short history of mould
We also had mould growth because of combination of
1. Defective/undersized fans
2. turning off fans at isolation switches
3. stuffed/closed vents
4. vents in window frame (behind curtains)
5. poor maintenance
6. poor thermal performance
7. clothes drying in Living Rooms
8. high humidity cooking
9. high humidity firewood
10. recirculation kitchen fans
…and now
• high levels of insulation (U)
• poor thermal bridging detailing (fRSi)
• high levels of airtightness (AP)

7. Natural Ventilation (NV) – issues
1. Differential pressure which is not consistent
2. Behavioural - Block up wall and window inlets
3. Overwhelming evidence to show natural ventilation (NV) under-ventilates (refer Scottish
study, 2014)
4. Studies showing CO2, humidity, VOCs high with Natural Ventilation to current standards
5. Part L 2018 refers to a maximum of 5 m3/m2/h to reduce heat loss but industry is easily
achieving 1.5 m3/m2/h @ no cost
…or even 0.8 m3/m2/h*
Tip: *site management quality control and detailing (sequencing and tolerances)

8. Definition of comfortable healthy buildings
Evidence has shown that the
optimum environment humans
feel comfortable in
 18-21 degrees Celsius
is the optimum
temperature
 45-55% humidity (>65%
unhealthy)
 400-600 ppm carbon
dioxide levels (>900 ppm
unhealthy)
…and whole house designed
systems helps to get you there

9. Solutions
2 types
System Mechanical Extract
Ventilation (MEV)
Mechanical
Ventilation Heat
Recovery (MVHR )
Basic description
- supply
Humidity controlled
continuous air
supply at same temp
as outside
Humidity controlled
continuous air
supply at same temp
as inside
Basic description
- exhaust
Humidity controlled
continuous extract
Humidity controlled
continuous extract
Part F compliance Specifically stated Specifically stated

10. 2 Types of DCV and HRV systems
Decentralised
dMEV
- see sample
Centralised
cMEV
- see sample
Decentralised
dMVHR
- see sample
Centralised
cMVHR
-see sample
Fans 3 1 7 1
Ducts No ducts Extract ducts only No ducts Supply and Return
Fan Type
Layout

11. Comparison DCV v HRV
Criteria dMEV cMEV dMVHR cMVHR
Ducts No ducts Extract ducts
only
No ducts Supply and
Return
Cost - S and I
(excl VAT)
€1800 – 2 bed
€2000 - 3 bed
€1800 – 2 bed
€2000 - 3 bed
€4000 – 2 bed
€4500 - 3 bed
€4000 – 2 bed
€4500 - 3 bed
Temperature
at inlet
Same as
outside
Same as
outside
*Just below
that of the
house
*Just below
that of the
house
Integrated
remote
monitoring
No No No Yes
DEAP input No No No ? Yes
Impact on
heating cost
None
assessed
None
assessed
€100/annum ? €100/annum ?
Basic characteristics affecting key decisions on social housing
– 2 bed @ 85 sqm and 3 bed @ 100 sqm

12. 2 Types : d = Decentralised and c = Centralised
Type dMEV cMEV dMVHR cMVHR
Ducts No ducts Extract ducts only No ducts Supply and Return
Fans – 2 bed 85 sqm 3 nr 1 nr 6 nr 1 nr
Noise at supply grill
Dishwasher = 55dBA
Fridge = 42dBA
Whisper = 30 dBA
Rural Nighttime = 25dBA
None
• 11 dBA extract*
• 35 dBA boost *
*@1m
None
• 20 dBA fan
• 35 dBA boost
11 dBA *
* @1m and prog to
OFF for night time
23 dBA*
• 26 dBA fan
• 45 dBA boost*
* @1m and prog to 10-
15dB for night time
Filters Yes No Yes Yes
Air Permeability
(door undercut)
Lowest possible Lowest possible
(6-10mm)
1.5 m3/m2/hr
(4-10mm)
1.5 m3/m2/hr
Maintenance Washable filter/yr Wash valve +
fan/2 yrs
Washable
filter/yr
Vacuum /3mths +
Replace filter/yr +
Service/2yr
Fan location 154mm dia. pipe to
wetrooms
Store or attic 154mm dia. pipe
in walls
Store or attic
Cost to run ++ €5/yr €30/yr €40/yr €70/yr
Impact on useable
floor space
No Yes
0.04 sqm + fan
No Yes
0.5 sqm + fan
++ Dependent on usage (number of showers, drying clothes etc)

13. Impact on space – cMEV in Rathdrum
2 housing project for Wicklow County Council
Project House Nr. Ventilation Type Reason(s)
Rathdrum 20 cMEV Ensure compliance
Kilbride 42 cMVHR 1. Concerns tenants
blocking up vents
2. Remote monitoring

14. Impact on space – cMEV in Rathdrum
Fan in attic
Vertical
extract riser
Vertical
extract riser
High level
boxing out

15. Impact on space – cHRV- 3 methods
1. Localised boxing out 2. Dropped ceiling 3. Integrated with ‘Easijoists’

16. WSN (Wireless Sensor Networks)
Measures
• Temperature - 0C
• Humidity - %
• Carbon dioxide - ppm
• Noise - dBA

17. Few Interesting Side Points
• Decentralised suits retrofits (as no ductwork ). Note: Watch AP
• Social housing may require attic fans to be caged and isolation switches to
be hidden
• MEV and MVHR works with closed stoves i.e. provided it has its own air
supply …so does not work with open fireplaces
• Kitchen extract is always separate
• Use a fire collar when penetrating a fire rated enclosure
• Integrated systems - can’t turn off ventilation system separately
…If you were designing your own home which one would you choose ?
dMEV or cMEV or dMVHR or cMVHR

18. Y factor

19. WSNs
Tip: Energy Show April 18th and 19th
This would never
have happened if
COADY were the ER
My dad said the
reason I am falling
asleep in class is
because of the levels
of CO2 in the
classroom. Averaged
last week 2043ppm
alone!
My mum said that my asthma is
getting worse because of the
levels of humidity averaged over
72% and CO2 averaged over
1956ppm last month in the
classroom
Miss I cant
concentrate
because it is 15.3
degrees in here .
Can we close the
windows ?

20. Thankyou
Q and A
NOTICE - Buildings are your homes and your communities, and you have a responsibility
to ensure that they are built in compliance with the “Building Regulations” which provide for
sustainability, safety and health and welfare of people in and around buildings