Building Construction Handbook. This 6th edition includes numerous revisions, amendments and additions in line with ongoing practice and legislative changes in building construction. Included are features of construction that are designed to economise and manage the use of fuel energy in buildings and limit the effect on atmospheric pollution.
It has been revised and expanded to take into account recent amendments to the Building Regulations Approved Documents and guidance from British and European Standards. Online lecture facilities include PowerPoint slides illustrating a selection of services areas, providing key diagrams for use with presentations and handouts.
The clear illustrations and complementary references to industry Standards combine essential guidance with a resource base for further reading and development of specific topics. Saturation pressure and temperature increase to emit heat at the condenser as heat energy is absorbed by the evaporator. As the liquid refrigerant changes to a gas through the expansion valve, it absorbs considerably more heat than during simple temperature change. This is known as the latent heat of vaporisation.
Detailed charts are produced by refrigerant manufacturers such as ICI Plc and professional organisations such as the Chartered Institution of Building Services Engineers. The diagram below indicates the outline of these charts. The principal curved line divides the three states of a refrigerant during pressure, temperature and energy change. For design purposes, the system operating characteristics can be superimposed on the chart to illustrate changes that occur during the refrigeration cycle.
By comparing the system vapour compression cycle on various charts, it is possible to determine the most suitable refrigerant for the purpose. This is necessary for correct reaction of the refrigerant. The cooling medium can be water or air. Water is more effective, but for practical purposes and health issues see page , air cooling is becoming more widely used.
The condenser coil on a domestic fridge is suspended at the back of the unit and exposed to ambient air to cool.
This same principle can be applied to small packaged and portable air conditioning units, possibly with the addition of a fan to enhance the cooling effect.
Larger-scale air conditioning installations have several high powered fans to cool the condensers. These fans can be mounted horizontally or vertically to draw high velocity air through the condenser coils.
The simplest and most inexpensive is a pond. Cooled water is drawn from one end and warm return water pumped into the other. Spray ponds are more efficient and may incorporate ornamental fountains as part of the process. Both have a tendency to accumulate debris and will require regular attention. More common are evaporative atmospheric cooling towers.
These are usually located on the building roof or within the roof structure plant room. Wall construction is louvred to permit crossflow of air. Internally the tower is either hollow or plastic baffled to increase the wetted contact area.
Warm water from cooling the condenser is discharged through a bank of high level sprays to cool as it descends through the air draught.
It is then recirculated to the condenser. Fan draught cooling towers are of two types: 1. The relatively large single fan is more economic in use and less likely to generate system noise and vibration. Therefore, towers must be maintained regularly and the water treated with a biocide, with regard to Workplace Health, Safety and Welfare Regulations They contain a vapour compression cycle refrigeration system, using the evaporator for cooling and the condenser for heating, with fan delivery of the processed air.
They are available in a wide range of power capacity, fan output, refrigeration and heating load for adaptation to various building types and situations. Small- to medium-sized buildings are best suited to these systems as it would be too costly and impractical to provide numerous units for use in multi-roomed large buildings.
These may be located in a store room and have short ductwork extensions to adjacent rooms. Packages contain all the processes of conventional air handling units, with the exception of a steam or water humidifier.
Humidification is achieved with condensation from the direct expansion DX refrigeration coil suspended in the air intake. For summer use, the cold DX coil cools incoming and recirculated air.
The hot condenser coil is fan cooled externally. Now the cold incoming air is warmed or pre-heated through the hot condenser coil and may be further heated by an electric element or hot water coil at the point of discharge. System types:. Self-contained single package. Split double package. May be free standing or attached to the structure.
One contains fan, filter, evaporator and expansion valve for interior location. The other contains condenser, fan and compressor for external location. The two link by refrigeration pipework. This has the advantage that one external unit can serve several interior units. This can be calculated or design manuals consulted for tabulated information. Graphical psychrometric details are also available for simplified presentation of data.
The chart outlined below is based on the calculated interrelationship of air properties at varying temperatures and conditions. In more detailed format, reasonably accurate design calculations can be applied. These are based on the processes shown plotted on the next page.
The easiest coordinates to obtain are the dry and wet bulb temperatures. These can be measured from a sling psychrometer, also known as a whirling or sling hygrometer. Two mercury-in-glass thermometers are mounted in a frame for rotation about the handle axis. One thermometer bulb has a wetted muslin wick. After rotation, the wet bulb temperature will be lower than the dry bulb due to the evaporation effect of moisture from the muslin. The extent of evaporation will depend on the moisture content of the air.
These processes can be represented by lines drawn on the psychrometric chart. Heating sensible is depicted by a horizontal line drawn left to right. Dry bulb temperature increases with no change in moisture content, but there is a reduction in percentage saturation. Heating latent is the effect of steam humidification and is represented by a rising vertical line. Dry bulb temperature remains the same, moisture content and percentage saturation increase.
Cooling sensible is depicted by a horizontal line drawn right to left. Dry bulb temperature decreases with no change in moisture content. Cooling by water spray humidifier is represented by an incline following the wet bulb temperature line.
This is known as adiabatic humidification. Both cooling processes show an increase in percentage saturation. Dehumidification is shown with a descending vertical line. Moisture content and percentage saturation decrease. Applications: 1.
Air enters the a. The process can be represented on a psychrometric chart by drawing a straight line between the two conditions and calculating a point relative to the proportions of mass flow rates. This is unrealistic, therefore energy exchangers should be overrated to accommodate this.
It differs in application, extracting heat from a low temperature source and upgrading it to a higher temperature for heat emission or water heating. The low temperature heat source may be from water, air or soil which surrounds the evaporator. A heat pump must be energy efficient; it must generate more power than that used to operate it. Allowing for efficiency of equipment and installation, a COP of 2 to 3 is more likely. However, small self-contained units are more common.
These are usually located under window openings for warm and cool air distribution in winter and summer respectively. To transfer the warmth in stale extract duct air, water may be circulated through coils or energy exchangers in both the extract and cool air intake ducts. This is known as a run-around coil. Using water as an energy transfer medium is inexpensive but limited in efficiency.
Use of a refrigerant is more effective, with an evaporator coil in the warm extract duct and a condenser coil in the cold air inlet duct. Heat energy in warm waste water from sanitary fittings may be retrieved and used to supplement space heating by using a heat pump. An insulated tank buried below ground receives the waste water before it flows to the sewer. Heat energy is extracted through an evaporator inside the tank.
Wheels range from mm to 4 m in diameter, therefore sufficient space must be allowed for their accommodation. They have an extended surface of wire mesh or fibrous paper impregnated with lithium chloride. Lithium chloride is an effective absorbent of latent heat energy in the moisture contained in stale air.
Heat from the exhaust air transfers to the inlet air and the purging section extracts the contaminants. The heat recovery duct or plate heat exchanger has warm exhaust air separated from the cool inlet air by metal or glass vanes. Heat from the exhaust vanes is transferred to the inlet vanes to warm the incoming air. Ducts must be well insulated to conserve energy and to reduce condensation.
Condensation should be drained at the base of the unit. To achieve this efficiently, many incorporate air conditioning and ventilation systems. Misuse of some of the system equipment may cause the following health hazards:. Humidifier fever see next page. Sick building syndrome see next page.
The bacterial infection was contracted by people; it has similar symptons to pneumonia. Of these, 29 died. Subsequently, numerous outbreaks have been identified worldwide.
They are generally associated with hot water systems see page 65 and air conditioning water cooling towers. The organisms responsible occur naturally in swamps and similar humid conditions. In limited numbers they are harmless, but when concentrated they contaminate the water in which they live. If this water is suspended in the air as an aerosol spray, it can be inhaled to establish lung disease in susceptible persons. Nevertheless, there have been cases of fit, healthy, young people being infected.
Use of packaged air conditioning with air cooling. Documented maintenance of existing wet cooling towers, i. It is caused by micro-organisms which breed in the water reservoirs of humidifiers whilst they are shut down, i. When the plant restarts, concentrations of the microorganisms and their dead husks are drawn into the air stream and inhaled.
Water treatment with a biocide is a possible treatment or replacement with a steam humidifier. The symptoms vary and can include headaches, throat irritations, dry or running nose, aches, pains and loss of concentration. All or some may be responsible for personnel inefficiency and absenteeism from work. Whilst symptoms are apparent, the causes are the subject of continued research. Some may be attributed to physical factors such as:. Noise from computers, machinery, lighting or ducted air movement.
Strobing from fluorescent strip lights. Static electricity from computer screens, copiers, etc. Fumes from cleaning agents. Glare from lighting and monitors. Unsympathetic internal colour schemes. Carpet mites. Other factors are psychological:. Lack of personal control over an air conditioned environment. No direct link with the outside world, i.
Disorientation caused by tinted windows. Working in rooms with no windows. Dissatisfaction with air conditioning does not provide the ideal environment.
More apparent may be lack of maintenance and misuse of air conditioning plant. Energy economising by continually recirculating the same air is known to cause discomfort for building occupants. The research continues and as a result of sick building syndrome, new building designs often favour more individual control of the workplace environment or application of traditional air movement principles such as stack effect.
These will be installed with regard to foul water processing and the possibility of disposing surface water via a sewer into a local water course or directly into a soakaway. The system is economical to install, but the processing costs at the sewage treatment plant are high. The rainwater from roofs and other surfaces is conveyed in a surface water drain into a surface water sewer or a soakaway.
This system is relatively expensive to install, particularly if the ground has poor drainage qualities and soakaways cannot be used. However, the benefit is reduced volume and treatment costs at the processing plant. For convenience and to reduce site costs, the local water authority may permit an isolated rainwater inlet to be connected to the foul water drain.
This is shown with the rainwater inlet at A connected to the foul water inspection chamber. Also, a rodding point is shown at B. These are often used at the head of a drain, as an alternative to a more costly inspection chamber.
A back inlet gully can be used for connecting a rainwater down pipe or a waste pipe to a drain. The bend or trap provides a useful reservoir to trap leaves. When used with a foul water drain, the seal prevents air contamination.
A yard gully is solely for collecting surface water and connecting this with a drain. It is similar to a road gully, but smaller. A rainwater shoe is only for connecting a rainwater pipe to a surface water drain. The soil and vent pipe or discharge stack is connected to the foul water drain with a rest bend at its base. It must have a centre-line radius of at least mm.
They eliminate isolated loads that manholes and inspection chambers can impose on the ground, thus reducing the possibility of uneven settlement. The system is also neater, with less surface interruptions. Prior to installation, it is essential to consult with the local authority to determine whether the system is acceptable and, if so, to determine the maximum depth of application and any other limitations on use. As rodding is only practical in one direction, an inspection chamber or manhole is usually required before connection to a sewer.
BS EN Drain and sewer systems outside buildings. Drains may be connected independently to the public sewer so that each building owner is responsible for the maintenance of the drainage system for that building. In situations where there would be long drain runs, it may be more economical to connect each drain to a private sewer. This requires only one sewer connection for several buildings.
Maintenance of the private sewer is shared between the separate users. Connection of a drain or private sewer to the public sewer can be made with a manhole. If one of these is used at every connection, the road surface is unnecessarily disrupted. Therefore a saddle is preferred, but manhole access is still required at no more than 90 m intervals.
Saddles are bedded in cement mortar in a hole made in the top of the sewer. This is essential to prevent the loss of trap water seals by siphonage or compression. The current practice of direct connection of the discharge stack and drain to the public sewer provides a simple means of ventilation through every stack.
In older systems, generally pres, an interceptor trap with a 65 mm water seal separates the drain from the sewer. The sewer is independently vented by infrequently spaced high level vent stacks. Through ventilation of the drain is by fresh air inlet at the lowest means of access and the discharge stack.
It may still be necessary to use this system where new buildings are constructed where it exists. It is also a useful means of controlling rodent penetration from the sewer. This is normally within the roof space, i.
An AAV prevents the emission of foul air, but admits air into the stack under conditions of reduced atmospheric pressure. AAVs are limited in use to dwellings of no more than three storeys, in up to four adjacent buildings. The fifth building must have a conventional vent stack to ventilate the sewer. In addition to the WC requirement, no branch pipes to other fittings may be higher than 2 m above a connection to a ventilated stack or the drain invert.
The maximum length of branch drain from a single appliance to a means of drain access is 6 m. For a group of appliances, it is 12 m. BS EN Gravity drainage systems inside buildings. Sanitary pipework, layout and calculation.
This is achieved by setting up sight rails, suitably marked to show the centre of the drain. These are located above the trench and aligned to the gradient required. At least three sight rails should be used. Wooden pegs are driven into the trench bottom at about 1 m intervals.
The required level is achieved by placing the bottom of the boning rod on each peg and checking top alignment with the sight rails. Pegs are adjusted accordingly and removed before laying the drains. For safe working in a trench, it is essential to provide temporary support to the excavation. Pipe runs should be straight and access provided only where needed, i.
They are an inexpensive application for accessing shallow depths up to mm to invert. Within this classification manufacturers have created a variety of fittings to suit their drain products. The uPVC bowl variation shown combines the facility of an inspection chamber and a rodding point.
Note: Small lightweight cover plates should be secured with screws, to prevent unauthorised access, e. They may be circular or rectangular on plan and preformed from uPVC, precast in concrete sections or traditionally constructed with dense bricks from a concrete base. The purpose of an inspection chamber is to provide surface access only, therefore the depth to invert level does not exceed 1 m. By comparison, manholes are large chambers with sufficient space for a person to gain access at drain level.
Where the depth to invert exceeds 1 m, step irons should be provided at mm vertical and horizontal spacing. A built-in ladder may be used for very deep chambers. Back-drops have also been used on sloping sites to limit the drain gradient, as at one time it was thought necessary to regulate the velocity of flow.
This is now considered unnecessary and the drain may be laid to the same slope as the ground surface. For use with cast-iron and uPVC pipes up to mm bore, the back-drop may be secured inside the manhole.
For other situations, the backdrop is located outside the manhole and surrounded with concrete. The term bedding factor is applied to laying rigid drain pipes.
This describes the ratio of the pipe strength when bedded to the pipe test strength as given in the relevant British Standard. This is due to the cradling effect of concrete, with a facility for movement at every pipe joint. This method may be used where extra pipe strength is required or great accuracy in pipe gradient is necessary. Class B bedding is more practical, considerably less expensive and quicker to use. If used with plastic pipes, it is essential to bed and completely surround the pipe with granular material to prevent the pipe from distortion.
Those shown below include three further classifications and corresponding bedding factors. Also shown is a suitable method of bedding flexible plastic pipes. In water-logged trenches it may be necessary to temporarily fill plastic pipes with water to prevent them floating upwards whilst laying. In all examples shown, space to the sides of pipes should be at least mm. If it is unavoidable and the trench is within 1 m of the building, the trench is filled with concrete to the lowest level of the building.
If the trench distance exceeds 1 m, concrete is filled to a point below the lowest level of the building equal to the trench distance less mm. Drains under buildings should be avoided.
Where it is impossible to do so, the pipe should be completely protected by concrete and integrated with the floor slab. If the pipe is more than mm below the floor slab, it is provided with a granular surround. Pipes penetrating a wall below ground should be installed with regard for building settlement. Access through a void or with flexible pipe joints each side of the wall are both acceptable.
They are quicker and simpler to make. The pipeline can be tested immediately. There is no delay in joint setting due to the weather. They absorb ground movement and vibration without fracturing the pipe. Existing clay drains will be found with cement and sand mortar joints between spigot and socket. Modern pipe manufacturers have produced their own variations on flexible jointing, most using plain ended pipes with a polypropylene sleeve coupling containing a sealing ring.
Cast iron pipes can have spigot and sockets cold caulked with lead wool. Alternatively, the pipe can be produced with plain ends and jointed by rubber sleeve and two bolted couplings. They may also have plain ends jointed with a uPVC sleeve coupling containing a sealing ring.
For conventional drainage systems without an interceptor trap, an anti-flooding trunk valve may be fitted within the access chamber nearest the sewer. If an interceptor trap is required, an anti-flooding type can be used in place of a conventional interceptor. An anti-flooding gully may be used in place of a conventional fitting, where back flooding may occur in a drain. Waste water from canteen sinks or dishwashers contains a considerable amount of grease.
If not removed it could build up and block the drain. Using a grease trap allows the grease to be cooled by a large volume of water. The grease solidifies and floats to the surface. At regular intervals a tray may be lifted out of the trap and cleaned to remove the grease.
Garage floor washings will contain petrochemicals and these must be prevented from entering a sewer. The floor layout should be arranged so that one garage gully serves up to 50 m2 of floor area.
The gully will retain some oil and other debris, which can be removed by emptying the inner bucket. A petrol interceptor will remove both petrol and oil. Both rise to the surface with some evaporation through the vent pipes. The remaining oil is removed when the tanks are emptied and cleaned. The first chamber will also intercept debris and this compartment will require more regular cleaning.
Contemporary petrol interceptors are manufactured from reinforced plastics for simple installation in a prepared excavation. In some situations site levels or basement sanitary facilities will be lower than adjacent sewers and it becomes necessary to pump the drainage flows. A pumping station or plant room can be arranged with a motor room above or below surface level.
Fluid movement is by centrifugal pump, usually immersed and therefore fully primed. For large schemes, two pumps should be installed with one on standby in the event of the duty pump failing. The pump impeller is curved on plan to complement movement of sewage and to reduce the possibility of blockage. The high level discharge should pass through a manhole before connecting to the sewer. Wastewater lifting plants. Layout and calculation. BS EN Waste water lifting plants for buildings and sites.
The advantages of an ejector are:. Less risk of blockage. Building Services Handbook summarises the application of all common elements of building services practice, technique and procedure, to provide an essential information resource for students as well as practitioners working in building services, building management and the facilities administration and maintenance sectors of the construction industry. Information is presented in the highly illustrated and accessible style of the best-selling companion title Building Construction Handbook.
The clear illustrations and complementary references to industry Standards combine essential guidance with a resource base for further reading and development of specific topics. Introduction 2. Cold Water Supply Systems 3. Hot Water Supply Systems 4.
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