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Requirement of thermal comfort in Building 

Thermal comfort indicates that situation of mind that will express satisfaction in respect of environmental thermal condition or if we say in simple word, the situation when peoples are not feeling either too much cold or too much hot.

Condition of human thermal comfort in respect of environment could not be satisfactory specified by a temperature range.

Human thermal comfort is very important because if people will not be satisfied with their environmental thermal comfort then it will lead to various issues such as
  • It will affect the health of manpower
  • It will affect their efficiency in doing work

Let us take an example the case of operation and maintenance of arc furnace or blast furnace or electric over head travelling crane in steel melting shop. Manpower has to face higher temperature during operation and maintenance of above equipment as this equipment is operating near or at higher temperature. 

In modern technology, it is desired to be an air conditioned cabin to operate the machinery in efficient way. Hence basically in order to utilize the 100 % efficiency of manpower resources, it is required to be suitable thermal comfort situation in work areas.

Outdoor design conditions

Before starting the designing, we will have information about the following points
  1. Wind speed, temperature & solar radiation 
  2. Convective heat transfer co-efficient 
  3. Building length and width
  4. No. of rooms and specifications 
  5. No. of window and specifications 
  6. No. of doors and specifications 
  7. Floor and roof specifications 
  8. Material of constructions for each component 

Once we will have information about above mentioned points, we may draw a floor plan to understand easily about the sizing and layout of duct.

We have to also discuss about the materials of construction for each component of building.

Roof -Construction

Conventional roof-attic-ceiling combination and it is also vented in order to withdraw the moisture with 6 inches. Insulation of fibrous bat & tvapor retarder and value of U is as mentioned as U=0.05 BTU/h ft2 F


Construction of wall is as following (for example)
Frame= 4 inch face brick
Insulation of fibrous batt = 3.5 in

Sheathing of Polystyrene = 0.75 in
Gypsum Board for wall= 0.5 in
U= 0.06 BTU/h ft2 F

Construction of floor

Such as mentioned that Floor is constructed with concrete slab of 4 in.


0.125 In of thickness inner and outer with clear double –glass
There is overhanging of window–glass of 2 ft at the top of window


Doors are made of material whose value of U= 0.32 BTU/h ft2 F

Design Conditions or restrictions 

Dry bulb temperature
50 %Relative humidity
96°F With 24°F daily range
74.6 F dew point


Let there are four persons are assigned to work at particular area.


U factor for every external surface are taken by assuming the wind velocity is equal to 7.5 m/h.

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