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Contents

Section 1 Introduction 

Section 2 Drainage

Section 3 Cold Water Supply

Section 4 Hot Water Supply

Section 5 Electricity

Section 6 Heating

Section 7 Heating Systems

Section 8 Gas

Section 9 Health & Safety Legislation 

 

Description:  This unit introduces the elements of buildings services required by a domestic building and the Health and Safety factors relating to them.

Author:  Gates MacBain Associates


Section 1  Introduction


The main function of the services system is to create and maintain a desired standard of comfort of a physical environment.  This will therefore ensure that the occupants have hot and cold water, the removal of waste products and a level of comfort with regard to warmth. In order for this to happen we need to look at each of these and we will do that under the following headings:
  • Drainage
  • Cold Water Supply
  • Hot Water Supply
  • Electricity
  • Heating
  • Heating Systems
  • Gas
  • Health & Safety Legislation




Section 2  Drainage



Aims and Objectives

At the end of this section you should be able to:
  • Describe the types of drainage systems both above and below ground


For the benefit of people health and comfort it is necessary to remove all water and waste products from a dwelling in a safe and efficient manner. The systems that we have to remove waste fall into the following categories:
  • Above Ground Drainage – deals with the system of pipework which carries soil and waste water from the appliances in the building to the below ground drainage.
  • Below Ground Drainage – the pipework which carries soil and waste away from the building to a source of treatment or disposal.
  • Rainwater Drainage – this can be a separate system carrying rainwater away from a property to a safe place for disposal.
A good place to start in understanding the systems is to read the appropriate chapters in the listed books. You should also ensure that you understand the requirements of the Building Regulations as they relate to Drainage and a link is provided to Approved Document H and N, which deal with this subject.   



Websites



Publications

  • Chudley, R. and  Greeno, R. (2006) Building Construction Handbook, 6th edn. Oxford: Butterworth-Heinemann.
  • Emmitt, S & Gorse, C (2005) Introduction to Construction of Buildings, Oxford, Blackwell.



Self-Assessment Task

  • Produce an annotated drawing illustrating the design features of a single stack soil and waste system for a two storey dwelling specifying the size of all pipes and traps.
  • Illustrate the pipework layout taking the effluence from the soil stack to an inspection chamber.





Section 3  Cold Water Supply




Aims and Objectives

At the end of this section you should be able to explain:
  • How cold water is brought into a property and transferred to the appliances.


Mains Connection 

Individual dwellings connect to the water main by a Goose neck and communication pipe. The pipes may be of lead (found in old building), copper or plastic. Lead will become brittle with age and is liable to crack. 

Certain soil conditions are likely to cause corrosion in metal pipes, ie. wet ashes, decomposing matter particularly if drainage is bad and there is a high sulphate or chloride content. In such case pipes will need protecting. 

Pipes must be at a minimum depth of 750mm for frost protection.  


Stop Taps 

Stop taps should be fitted at the point of entry of the water supply into the building, in addition to the Water Authorities onto the cartilage and at each appliance.    


Types of Cold Water Distribution Systems  

Direct or Non-storage    

All the plumbing fittings are supplied with cold water direct from the mains.  A cold water cistern is normally used to feed the hot water supply system though water heaters are available which can be fitted direct from the mains. 

Advantages 
  • Less pipe work, smaller or no cistern make it cheaper to install.
  • Drinking water is available at all draw of points.
  • Smaller cistern can be sited below the ceiling.
  • In systems without a cistern there is less risk of water pollution.

Indirect or Storage   

All plumbing fittings except the kitchen sink is supplied with cold water via a storage cistern, which can also be used to supply the hot water supply system.  

Advantages 
  • Cistern provides a reserve of water if supply is interrupted.
  • Reduced water pressure on taps reduces wear and noise.
  • Less risk of pollution to drinking water by back siphonage.
  • Lower demand on the water main.

Contamination of Water Supply by Back Siphonage 

This is where water is drawn back into a pipe due to a partial vacuum or a negative pressure.  It occurs when an outlet is submerged in water which may be contaminated.   This can occur when a great demand is made on the water supply, which draws water from the pipes. Siphonic action can then draw water from an appliance to contaminate the mains.  



Websites



Publications

  • Chudley, R. and  Greeno, R. (2006) Building Construction Handbook, 6th edn. Oxford: Butterworth-Heinemann.



Self-Assessment Task

  • Illustrate a typical cold water distribution system for a two storey domestic building.





Section 4  Hot Water Supply




Aims and Objectives

At the end of this section you should be able to explain:
  • The methods used to heat and distribute water within a dwelling.


Hot water is required for washing and culinary purposes.  The quantity of hot water required will depend on the following: 
  • Type of building and number of appliances requiring hot water.
  • Number of occupants and their needs.
  • Extent to which cooking and laundering is carried out.
  • Any special processes which are carried out.
The temperature required will depend on the use of the water ie for showers 45oC, for culinary 65 - 70oC. Industrial applications may require higher temperatures. 

In temperatures over 60oC scale formation is accelerated in hard water districts; also, greater risk of occupants  scalding themselves.  


Types of Systems 

Hot water systems are classed as either Instantaneous or Storage. 


Instantaneous 

These heat water as the water passes through the appliance.  The cold water can come from a storage cistern or directly from the mains,  it flows through a heat exchanger  and out through the tap. 

As no water is stored heat loss is kept to a minimum, and only water which is used is heated. 


Storage    

This is where water is piped to a vessel where it is raised to a required temperature and stored in that vessel  until it is drawn off from the outlet taps. The storage vessel contains sufficient capacity to meet the normal hot water requirements.  

Storage systems are subdivided into direct or indirect depending on how they are heated. 


Direct    

The water to be used is heated directly by a heat source. 


Indirect  

The water is heated by a heat exchanger located within the storage vessel, this is heated by an external source.  The storage system is also known as a centralised as the water is stored centrally  and  distributed by pipework to the  draw  off points.  


Advantages of a centralised system 
  • The storage vessel contains sufficient supply to meet peak demand.
  • Cheaper fuels can be used. (Particularly for large buildings)
  • Fire risk reduced and confined to the boiler room.
  • One heating plant reduces maintenance.

Types of storage cylinders 

In domestic situations  the  hot water is stored  in  a  copper cylinder, this can be direct, indirect or primatic. Although the trend now is to have the water heated as it is drawn off rather than stored. 

The water can be heated by electric, gas, oil or solid fuel. 

In domestic installations the water is heated by a wall or floor mounted boiler, or by a back boiler behind a fire in, ie the living room.     


Regulations   

All water systems, fittings and equipment in a building, which connect to the public water supply, must conform to the Water Supply (Water Fittings) Regulations 1999. Details of these can be seen via the web link below.    



Publications

  • Chudley, R. and  Greeno, R. (2006) Building Construction Handbook, 6th edn. Oxford: Butterworth-Heinemann.



Self-Assessment Task

  • Illustrate a typical hot water distribution system for a two storey domestic building.



Section 5  Electricity




Aims and Objectives

At the end of this section you should be able to:
  • Explain the way that electricity is distributed around a building.


This section will introduce you to electricity in a dwelling; after you have read through this section you should visit the website Overview of Electrics and read the appropriate sections in the books relating to this section in order to ensure you fully understand the systems use.   

Electricity is brought into the dwelling from the supply cable. On entry it goes into the Power company’s fuse which allows the supply to be disconnected by the provider.  From there leads are taken to the power companies meter and then to the consumer unit which provides protection to the wiring within the building and enables the power to be switched off by the property owner/occupier.     


Consumer Unit   

A consumer unit is a box of fuses or breakers, designed to protect the wiring, building and occupants, see below.       




The one shown above is fitted with rewirable fuses which are either wired or cartridge fuses alternatively a miniature circuit breakers (MCBs) can be fitted. This type of consumer unit was in common use until 2001 when wiring regulations required residual current device (RCD) such as the one illustrated below.           




With the introduction of the 17th Edition IEE Wiring Regulations. Consumer units must now provide RCD protection to all cables embedded in walls, with certain exceptions such as smoke alarms or doorbells.     


Wiring Circuits   

The electricity is carried by the means of cables and are formed into circuits with their own protection (ie fuse, circuit breaker). These are described as either radial or ring.   


Radial Circuit 

This is where power is transmitted from point to point by a single length of cable linking each point to the next. There are a number of options for the wiring which can be a loop-in or junction box system. It runs from the consumer unit and finishes at the last connected device. This system is normally used for lighting: To understand the wiring of the lighting circuit visit the weblink below.   


Ring Circuit 

A ring circuit (often refered to as a ring main) provides two independent conductors for live, neutral and earth which travel around the building from the consumer unit and connect to each load or socket as seen in the illustration below. The use of the two connectors enables the use of smaller-diameter wire than would be used in a radial circuit.            





Building Regulations   

As from January 2005 all electrical work within a domestic setting must comply with Part P of the Building Regulations. A copy of these Regulation can be found by clicking on Approved Document P in the web box below. 

The purpose of these regulations is to improve safety and reduce accidents caused by incorrect wiring and use of electricy. For more details of the Health & Safety aspects you should visit the Health and Safety Executive website shown below who have an area devoted to Electrical safety at work  

An introduction to electrical systems can be obtained form Building Construction Handbook.        



Websites



Publications

  • Chudley, R. and  Greeno, R. (2006) Building Construction Handbook, 6th edn. Oxford: Butterworth-Heinemann.



Self-Assessment Task

  • Produce a drawing and explain the systems for distributing electricity around a domestic building.




Section 6  Heating




Aims and Objectives

At the end of this section you should be able to explain the:
  • Essentials of thermal comfort
  • Factors which affect the thermal internal environment


Thermal Comfort 

The thermal comfort of the occupants is related to the  thermal functions  of the body, which must be controlled within  certain limits depending on the type of use of the building,  and the age and activities of the occupants.

The greatest degree of thermal comfort exists when:
  • Air temperature is between 16 - 22oC.  Temperature difference between head and feet is no more than 3oC.
  • Surface temperature is at or above air temperature.
  • Air movement is preferably variable between 0.1 and 0.25 m/s, if more draughts are experienced with the angles and necks most venerable.
  • Humidity is between 40 - 60%.
 
Factors Affecting the Internal Environment

Many factors affect the internal environment and consequently the amount of heat required to be put into a room to achieve the thermal comfort of the occupants, these are:
  • Occupancy Heat Gain - heat given out by a person - 100w if sleeping, 300w doing manual work. Electrical Appliances - 1 watt of electrical power will degrade to 1w heat power. 
  • External Weather Conditions - Consider degree days; heat will pass from a warm material to a cold one, from the warm side of a wall to the cool side.Exposure   - cold winds blowing over a building will take heat away, heat loss is affected by air movement. 
  • Materials of Construction   - type and thickness.  Heat will pass through a material according to its thermal conductivity; dense materials conduct heat better than less dense (these being used for insulation ie rockwool, fibre glass). 

If insulation is placed on the inside of the building the building will heat up quicker because it will not have to heat up the fabric, just the air. If insulation is on the outside it will take  longer  as  the walls themselves will have  to  be  heated, however,  once  the  heat has been turned off the building  with internal  insulation will cool down quicker,  whereas the heat in the walls of the externally insulated building will radiate  heat back into the room. The thicker the walls the greater effect this has, and the longer it takes to heat up, or the heat to work its way through ie. Churches being cool in summer.  


Solar Gain 

The intensity of this can be controlled by the orientation of the building, and the direction, size and shape of the windows.  It is not a good idea to reduce their size as this will reduce the levels of illumination.Heat gain from windows can be reduced by:
  • Internal blinds.
  • External blinds and shades.
  • Recessed windows.
  • Heat reflecting/absorbing glass.
The time of year is also relevant as shades can be used in summer to  reduce solar gain but will allow sunshine to enter in  winter when the sun is low.  


Air Changes  

As the air changes, either by natural or mechanical ventilation, it removes heat with it. (Building Regulations specifies a minimum number of air changes per hour)In a balanced system   of  mechanical  ventilation  a  heat  exchange  unit  is incorporated  to  use this heat to  heat  incoming  air.  Another advantage of mechanical ventilation is that it removes smells and moisture vapour thus reducing condensation and mould growth. 


Shape and Type of Building

A  semi-detached  house will lose  less heat than a detached,  while a terrace will lose  even less as it is not exposed on two of its’ sides. 


Heat Loss 

Heat will be lost from a building through the following ways: 
  • Draughts
  • Conduction of heat through the building materials
  • Radiation of heat from the building as a whole
  • Convection of heat by the air in contact with the outside of the building.
In order to ensure the comfort of the occupants all heat losses must be allowed for and an appropriate amount of heat put into the building to maintain the temperature at a comfortable level.  



Publications

  • Chudley, R. and  Greeno, R. (2006) Building Construction Handbook, 6th edn. Oxford: Butterworth-Heinemann.



Self-Assessment Task

  • List and explain the essentials of thermal comfort and the factors which affect the thermal internal environment.




Section 7  Heating Systems




Aims and Objectives

At the end of this section you should be able to explain:
  • The types of heating systems available


Types of Heating 
  • Direct
  • Central
 
Types of Fuel 
  • Solid Fuel - coal, coke, biofuel
  • Oil
  • Gas
  • Electricity

Types of Central Heating Systems 
  • Hot water circulatory Systems
  • Ducted warm-air Systems
  • Fabric-borne Systems (heated ceiling panels, underfloor heating).
 
Hot Water Systems 

Water is generally used as it is able to convey more heat per diameter of pipe than any other commonly found media. The higher the temperature of the water the smaller the pipes and the emitters required. When low pressure hot water is used for heating systems the temperature of the water is below boiling point, usually 80oC on the flow. 

The water may circulate by either natural convection or by the use of a pump.  The pump allows a quicker response time and smaller pipes to be used. 

Systems may be open, which requires a feed and expansion cistern, or sealed which uses a flexible membrane expansion vessel. 

With the other exception of the different way that is used to allow for the expansion of the water when it becomes hot, the layout of the systems are the same. 

Various configurations are available for the layout of the pipework carrying the water to and from the heat emitters, though these are generally classed as one or two pipe systems. 


One-pipe System 

These  require less pipe work and are cheaper to  install,  although they are not as efficient as the two-pipe system due to all water passing  through each  radiator, the radiator at the end  of  the system  receives water which is cooler than that received by  the first  radiator.  Also, although the pump forces water round the pipe work it does not force it round the radiator which relies on natural convection.       


One-pipe system   


Two-pipe System 

When water passes through a radiator it is returned directly back to the boiler for re-heating, this ensures a better balance of heat to each emitter.  If pumped the water is forced through each emitter.      



Two-pipe system    


Size of Pipes   

The size of the pipes will depend on the size of the building and the heat load. For houses and small buildings 15 and 22mm pipe is used, although Micro or Mini-bore systems use pipes with diameters of 6, 8, 10 and 12mm.   


Size of Emitters   

These will depend on the type of emitter and the heat loss from the building.   


Control of Heating   

Thermostatic control can be achieved by:  
  • Thermostats used to control the water temperature in the boiler.
  • Thermostats used to control the pump and boiler according to the air temperature.
  • Zoning valves control the temperature within a part of the system by cutting off the flow to that part of the system at  a given temperature.
  • Three-way port valve can be used as a mixing or diverting valve to ensure that the water temperature is constant.  It does this by either diverting hot water away from a part of the system if it reaches a given temperature, or by mixing it with water from the return pipe.
   



Publications

  • Chudley, R. and  Greeno, R. (2006) Building Construction Handbook, 6th edn. Oxford: Butterworth-Heinemann.



Self-Assessment Task

  • Describe the advantages and disadvantages of the two types of heating system.




Section 8  Gas



Aims and Objectives

At the end of this section you should be able to:
  • Explain the requirements applicable to the installation of gas in a dwelling.


Regulations All work relating to gas must be carried out in compliance to the Gas Safety (installation and use) Regulations 1994. These cover the safe installation, maintenance and use of gas systems  and appliances in domestic and commercial premises. 

The regulations can be found by using the web links below. Both of the books shown below will set out the way gas is brought into the building and its’ requirements.  



Websites



Publications

  • Chudley, R. and  Greeno, R. (2006) Building Construction Handbook, 6th edn. Oxford: Butterworth-Heinemann.
  • Emmitt, S & Gorse, C (2005) Introduction to Construction of Buildings, Oxford, Blackwell.



Self-Assessment Task

  • Covering the main points, briefly describe the requirements applicable to the installation and maintenance of gas in a dwelling.





Section 9  Health & Safety Legislation




Aims and Objectives

At the end of this section you should be able to:
  • Summarize the Health and Safety legislation as it affects each of the sections dealt with in this unit.


You will be looking at Health & Safety Legislation in some detail in a number of other units though before finishing this unit you should have an overview on how it affects the construction process that we have looked at throughout this module.  In some of the unit sections you will have explored some of the specific requirements relating to types of work such as electric or gas.  Though you should ensure you understand a number of the basic requirements.  The starting point for this would be to read the section on Health and Safety in  the Construction Handbook shown below.  You can then visit the Health & Safety Executive website, a link to which is provided below. 



Websites



Publications

  • Chudley, R. and  Greeno, R. (2006) Building Construction Handbook, 6th edn. Oxford: Butterworth-Heinemann.



Self-Assessment Task

  • Summarise how Health & Safety legislation affects each of the sections dealt with in this unit.





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