Building Services, Technology and Design

Roger Greeno

• Éditeur: Routledge
• Année: 2014
• ISBN:
  9781317889090
• Édition: 1
• Sujet: Architecture
• Sous-sujet: Architecture General

Building Services, Technology and Design provides a concise guide to the installation and design of principal services in domestic and commercial buildings. It covers the level 2 module of The CIOB's Education Framework and is officially sanctioned by the CIOB as the recognised text for that module. The book combines theory, design and application in one volume and is supported throughout with illustrations, design examples, tables and charts.Services covered include: cold and hot water; heating; ventilation; air conditioning; gas; electricity; security; fire control; sanitation; drainage and transport systems. Building Services, Technology and Design is a core text for the CIOB level 2 module, as well as BTEC HNC/D building studies and degree courses in building. It is also an essential reference for all members of the facilities management and construction industry.

1 Cold water supply

Hydrological cycle

The origins of drinking water are found in the hydrological or water cycle. This continuous process includes evaporation of moisture from the sea, rivers and lakes to form clouds. The condensation droplets coalesce and fall as rain to replenish the water levels.

Extraction

In the United Kingdom, water is derived from:

1. Surface sources, i.e. rivers and large lakes
2. Boreholes into aquifers (water-bearing strata)
3. Roofs, paved areas and shallow wells.

rhe first two categories lend themselves to subsequent filtration and chemical treatment, before distribution and consumption, as shown in Figure 1.1. The latter category could be contaminated and are only used in remote locations.

In some parts of the world where rainwater is scarce, desalination plant is used to process sea water, but this is very expensive.

Processing and distribution

In Figure 1.1 the three principal sources of United Kingdom water are identified. About one-third of consumption comes from each, although regional variations are inevitable, e.g. the Highland areas of Scotland will provide the bulk of water for that area, while the flat Fenlands of East Anglia will need boreholes.

Surface water is stored in man-made reservoirs or impounding reservoirs, the latter created from damming valleys to create catchment areas and to provide the potential for hydroelectricity generation. Coarse and fine sand filtration removes most debris and impurities before a minute amount of chlorine is added to classify the water drinkable. Borehole supplies are well filtered through the strata and normally only require chemical treatment.

After processing, the water is pumped to a high-level storage reservoir or

Figure 1.1 The water process

water tower for gravity distribution through iron or uPVC pipes (coloured blue) jointed as shown in Figure 1.2.

Connection to buildings

The grid distribution of underground pipework enables sections to be isolated for repair and maintenance without severe local disruption. Connections to the grid are made by the local water authority or its approved contractor at the expense of the developer or building owner. An isolation stop valve is usually provided at the crown of the water main and a communicating pipe terminated inside the property boundary with another stop valve for the building owner's use. This pipe remains the water authority's, but the service pipe thereafter is the responsibility of the building owner. A typical installation is shown in Figure 1.3.

Figure 1.2 Jointing of water mains

Figure 1.3 Domestic water supply

Figure 1.4 Meter housing

Water meters

Water meters are supplied at the discretion of the local water authorities and most new buildings are required to have them. The preferred location is underground, just beyond the property boundary as shown in Figure 1.3. If this is impractical, location within the building at the base of the rising main may be agreed with the water authority. Figure 1.4 shows a possible installation in a waterproof chamber, with an electrical earth continuity bond for metal pipework should the meter be removed. Figure 1.5 is an innovative patent meter connection to an existing stop valve body.

Internal distribution, direct and indirect systems

Direct systems are not favoured by many water authorities, as they require a consistent supply of pressurised water, which may be difficult during periods of peak demand. In the Highland areas this is viable where the sources of supply and distribution are well elevated relative to draw-off points, but for most areas the indirect system is mandatory. Although more expensive to install, with its larger cistern and almost twice as much pipework, it has the advantage of constant water pressure from the storage cistern which reduces the possibility of back siphonage (possible negative mains pressure drawing dirty water back into the main, e.g. hosepipe attached to an outside tap, with the open end submerged in a pond!).

Figures 1.6 and 1.7 provide a comparison of the systems with characteristics of installations. Note that even with an indirect system, ...