Table 12 Winter Design Temperatures and Air Changes

Type of building	Temperature	Air changes
	(°C)	(/h)

Art galleries and museums	20	1

Assembly halls, lecture halls	18	0.5

Banking halls:
large (height over 4 m)	20	1
small (height less than 4 m)	20	1.5

Bars	18	1

Canteens and dining rooms	20	1

Churches and chapels:
up to 7000 m²	18	0.5
over 7000 m²	18	0.25
vestries	20	1

Dining and banqueting halls	21	0.5

Exhibition halls:
large (height over 4 m)	18	0.25
small (height less than 4 m)	18	0.5

Factories: sedentary work	19	see note
light work	16	below
heavy work	13

Fire stations, ambulance stations:
appliance rooms	15	0.5
watch rooms	20	0.5
recreation rooms	18	1

Flats, residences and hostels:
living rooms	21	1
bedrooms	18	0.5
Bed sitting rooms	21	1
bathrooms	22	2
lavatories and cloakrooms	18	1.5
service rooms	16	0.5
staircases and corridors	16	1.5
entrance halls and foyers	16	1.5
public rooms	21	1

Gymnasiums	16	0.75

Hospitals:
corridors	16	1
offices	20	1
operating theatre suite	18-21	0.5
stores	15	0.5
wards and patient areas	18	2
waiting rooms	18	1

Hotels:
bedrooms (standard)	22	1
bedrooms (luxury)	24	1
public rooms	21	1
staircases and corridors	18	1.5
entrance halls and foyers	18	1.5

Laboratories	20	1

Law Courts	20	1

Libraries:
reading rooms (height over 4 m)	20	0.5
reading rooms (height below 4 m)	20	0.75
stack rooms	18	0.5
store rooms	15	0.25

Offices: general	20	1
private	20	1
stores	15	0.5

Police stations: cells	18	5

Restaurants and tea shops	18	1

Schools and colleges:
classrooms	18	2
lecture rooms	18	1
studios	18	1

Shops and showrooms:
small	18	1
large	18	0.5
department store	18	0.25
fitting rooms	21	1.5
store rooms	15	0.5

Sports pavilions: dressing rooms	21	1

Swimming baths:
changing rooms	22	0.5
bath halls	26	0.5

Warehouses:
working and packing spaces	16	0.5
storage spaces	13	0.25

For infiltration rates in factories see CIBSE Guide A4, page A4_9 and Table A4.9.

The tabulated infiltration rates are based on normal exposure and on an average ratio (25%) of openable areas (windows and doors) to external wall area. If the ratio much exceeds 25% in one external wall only, increase the infiltration by one quarter; if it is the case for two or more walls, an increase of one half should be allowed. On severely exposed sites, a 50% increase should be allowed, and on sheltered sites the infiltration rate may be reduced by one third. During periods when the building is unoccupied the infiltration rate can be taken as half that obtained in normal use.

The air-change rate in rooms in tall buildings may be increased above the values given by the direct action of the wind, and by stack effect. The design of tall buildings should include barriers against vertical air movement through stairwells and shafts to minimize stack effect. If this is not done, the balance of internal temperatures can be seriously upset.

Where warm air is supplied mechanically for ventilation, rates of infiltration applicable to a closed building (i.e. half the tabulated values) should be used for calculating the room heat requirements, so that room temperatures can be maintained, if required, when the mechanical ventilation is not operating. Heat for the warm air requirements must, however, be included in the total load on the central plant.