Building Services and Environmental Control
Building Services and Environmental Control tests basic water, drainage, heating, electrical and ventilation systems, and the environmental principles behind them. You should be able to trace a service, state a safety requirement and calculate a simple fall or energy figure.
Core rules
- An indirect cold-water system uses a storage cistern with a float valve, a vent pipe and distribution pipes. A trap holds a water seal, typically about 75 mm, to stop sewer gas entering a building.
- Drainage relies on gravity. A 100 mm pipe commonly falls between 1:40 and 1:110; the fall must be steady, with rodding eyes at changes of direction.
- U-value measures heat transfer through a construction in W/m²K; lower is better. R-value measures resistance; higher is better. Insulation, draught sealing and controlled ventilation reduce heat loss.
- Wet rooms need extract ventilation; combustion appliances need a permanent air supply and a flue.
Worked example
A drain runs 8 m at a gradient of 1:40. Fall = length ÷ gradient = 8 ÷ 40 = 0.20 m, or 200 mm. If the upstream invert is 300 mm below ground, the downstream invert is 500 mm below ground. Check that the pipe still has cover and that the gradient is not so steep that water runs ahead of solids.
Traps
Confusing U-value with R-value, omitting a trap, laying a drain flat or backfalling it, and blocking a vent are common errors.