Building Services Engineering 5th Edition Handbook

Hot- and cold-water supplies 195
Table 6.5 Recommended allocation of sanitary fittings.
Building
accommodation
No. of
occupants
Male Female Urinals Male Female
Staff 1–100 1 + 1 per 25 1 + 1 per 14 1 + 1 per 25 1 + 1 per 25 1 + 1 per 14
Over 100 + 1 per 30 + 1 per 20 + 1 per 30 + 1 per 30 + 1 per 20
Transient public 1–200 1 per 100 2 per 100 1 per 50 1 per WC 1 per WC
200–400 1 per 100 + 1 per 100 1 per 50 1 per WC 1 per WC
Over 400 + 1 per 250 + 1 per 100 1 per 50 1 per WC 1 per WC
Source: Reproduced from IHVE Guide (CIBSE, 1986 [IHVE, 1970]) by permission of the Chartered Institution of Building
Services Engineers.
Table 6.6 Allocation of sanitary accommodation
for Example 6.4.
Staff
Students
2 male WCs 4 male WCs
2 female WCs 4 female WCs
2 urinals 8 urinals
2 male basins 4 male basins
2 female basins 4 female basins
EXAMPLE 6.4
A new university building is to have 70 male and 20 female staff. The student population
is considered to be 400 males and 300 females. Students are considered to be transient
public. Recommend a suitable allocation of sanitary accommodation.
Using Table 6.5, we obtain the results given in Table 6.6. The accommodation is to be distributed
around the site to ensure uncongested access and reasonable walking distances. A tall
building would ideally have toilets on each floor, close to the stairways and lifts, so that all the
pipework can run vertically in a service duct. At least one toilet for disabled people is to be
included at suitable location, with appropriate access, in the above schedule.
Materials for water services
The materials used in hot- and cold-water systems are listed in Table 6.7. Corrosion protection is
provided by ensuring that incompatible materials are not mixed in the same pipework system, by
recirculating the water in central heating systems to reduce fresh oxygen intake, and by adding
inhibiting chemicals to the water. Hot- and cold-water service systems are continually flushed
with fresh water, making it necessary to use galvanized metal, copper or stainless steel.
Copper and galvanized steel should not be used in the same system because electrolytic action
will remove the internal zinc coating and lead to failure. A galvanized metal cold-water storage
tank can be successfully used with copper pipework as the low temperature in this region limits
electrolytic action. Heat accelerates all corrosion activity.
Black mild steel is used in recirculatory heating systems, and an initial layer of mill scale,
which is metal oxide scale formed during the high-temperature working of the steel during its