climatology

1. • MAHONEY’S TABLES
• INTRODUCTION
• MEANING
• NEEDS
• APPLICATION METHOD
• EXPERMENTAL STUDY
• CONCLUSION

2. MAHONEY’S TABLES
• The Mahoney tables are a set of reference
tables used in architecture, used as a guide to
climate-appropriate design. They are named
after architect Carl Mahoney, who worked on
them together with John Martin Evans,
and Otto Königsberger. They were first
published in 1971 by the United Nations
Department of Economic and Social Affairs.

3. INTRODUCTION
• The Mahoney Tables (Evans, 1999; Evans,
2001) proposed a climate analysis sequence
that starts with the basic and widely available
monthly climatic data of temperature,
humidity and rainfall, such as that found in
HMSO (1958) and Pearce and Smith (1990), or
data published by national meteorological
services, for example SMN (1995). Today, the
data for most major cities can be downloaded
directly from the Internet

4. MEANING
• The tables use readily available climate data and simple calculations to give design guidelines,
in a manner similar to a spread sheet, as opposed to detailed thermal analysis or simulation.
There are six tables; four are used for entering climatic data, for comparison with the
requirements for thermal comfort; and two for reading off appropriate design criteria. A
rough outline of the table usage is:
• Air Temperatures. The max, min, and mean temperatures for each month are entered into
this table.
• Humidity, Precipitation and Wind. The max, min, and mean figures for each month are
entered into this table, and the conditions for each month classified into a humidity group.
• Comparison of Comfort Conditions and Climate. The desired max/min temperatures are
entered, and compared to the climatic values from table 1. A note is made if the conditions
create heat stress or cold stress (i.e. the building will be too hot or cold).
• Indicators (of humid or arid conditions). Rules are provided for combining the stress (table 3)
and humidity groups (table 2) to check a box classifying the humidity and aridity for each
month. For each of six possible indicators, the number of months where that indicator was
checked are added up, giving a yearly total.
• Schematic Design Recommendations. The yearly totals in table 4 correspond to rows in this
table, listing schematic design recommendations, e.g. 'buildings oriented on east-west axis to
reduce sun exposure', 'medium sized openings, 20%-40% of wall area'.
• Design Development Recommendations. Again the yearly totals from table 4 are used to
read off recommendations, e.g. 'roofs should be high-mass and well insulated'.

5. NEEDS
• The procedure to be adopted for the analysis of the climate of a place is as follows:
Obtain weather data.
• Find out which months are comfortable (hot or cold), using mean temperature and
relative humidity. This also gives an indication of the severity of the climate.
• Identify the climatic zone to which the city belongs for adopting appropriate
strategies to achieve comfort.
• Establish the positive and negative aspects of climate for a particular season. For
example, shading from the sun may be needed during overheated periods. Which
are those seasons, and what is the position of the sun in the sky ? During the same
period, wind may be required to alleviate discomfort. What are the speed and the
direction of the wind during that period ?
• Adjust the impact of local microclimatic conditions and the urban context in the
analysis. For example, in northern hemisphere, larger buildings in the south create
shadow zones in the north. Thus the amount of direct solar radiation falling on a
smaller building in the north is affected. Also, the presence of a large building, or
the orientation of the street can impact the speed and direction of wind.
• Finalise the zoning of the site. For example, the presence of water bodies on the
site may be advantageous in a hot and dry zone. The wind, if allowed to pass over
the water body can increase the potential for evaporative cooling. So the building
has to be oriented facing the wind.

6. EXPERMENTAL STUDY
• The effects of sun, wind and light on a particular site can be analysed in many
ways depending on the type of information available for a place. They can be
graphical in nature (such as bioclimatic chart [4, 11] and psychrometric chart
[11]), or in worksheet format (such as Mahoney table [19]). One could also use
computer software such as Climate Consultant [20] or Therm [21]. For
example, the effects of temperature and humidity can be plotted on a
bioclimatic.
• Or psychrometric chart [11] to understand the climate and suggest ways of
expanding the comfort zone. Similarly, Mahoney tables facilitate diagnosis of
climate and provide design recommendations. The computer software
‘Therm’ evaluates climatic factors and predicts the adaptive comfort index.
Climate Consultant, in addition to analysing weather variables, provides
recommendations for building design from the point of view of comfort
requirements.
• To generate relevant information on the climate of a place, one can use
graphical procedures or adopt the measurement route, or resort to
computational techniques. The measurement route can be either analysis of
the recorded data available from Indian Meteorological Department and other
sources (section 2.2), or for conducting on-site measurements. Table 2.5 lists
various techniques that can be adopted to generate and analyse climatic
factors.

7. APPLICATION METHOD

8. CONCLUSION
• If it is our power to decide the temperature
inside a building, then we have to know
exactly what it should be. So the
environmental scientists set about deciding
what is the climatology of the particular zone.