Building Services

1. Building Services By Dr David Johnston – licensed under the Creative Commons Attribution – Non-Commercial – Share Alike License http://creativecommons.org/licenses/by-nc-sa/2.5/

2. ENVIRONMENTAL SCIENCE & SERVICES - LEVEL 1 Natural and artificial lighting Dr David Johnston

3. Objectives By the end of this lecture you should: • Be aware of the energy implications of lighting. • Understand why buildings require lighting. • Understand what is meant by the term ‘daylight factor’. • Be able to identify a number of innovative daylighting technologies. • Be able to identify the advantages of daylighting. • Understand what is meant by the terms general lighting, localised lighting and local lighting. • Be aware of the various factors that influence artificial lighting energy consumption.

4. Context In 2004, the domestic sector was responsible for about 30% of total UK energy use and about 27% of carbon dioxide emissions . Around 20% of the energy delivered to the domestic sector was used for lighting, powering appliances and cooking. The other 80% was used for space (60%) and water heating (20%). In terms of CO2 emissions, lights, appliances and cooking account for around 27% of the total CO2 emissions attributable to the domestic sector. In 2002, 16% of domestic electrical consumption was attributable to internal lighting. Lights and appliances represent the area of greatest growth in domestic energy use. In well insulated low energy dwellings, the CO2 emissions attributable to lights and appliances can be as high as 75% (Bell, Lowe & Johnston, 1996). In the non-domestic sector, lighting is the second largest consumer of energy – approximately 40% of all of the electrical energy used in non-domestic buildings is attributable to lighting.

5. Lighting Lighting within the indoor environment can be considered to have three basic purposes: • To enable the occupants to work and move about in safety. • To enable tasks to be performed. • To make the interior look pleasant. Lighting for safety or performing visual tasks [Source: CIBSE, 2002] There are two principle ways in which a building can be lit. These are: • Naturally - by daylight received from the sky. • Artificially - by electric lamps or other artificial light sources.

6. Daylighting The primary reference in the UK for daylighting criteria is BS 8206: Lighting for buildings: Part 2: Code of practice for daylighting (BSI, 1992). The Standard describes the qualities to be achieved in: • Providing a view. • Sunlight penetration. • General room lighting. • Task lighting. The British Standard treats daylight as two distinct sources of light: • Sunlight – That part of solar radiation that reaches the earth’s surface as parallel rays after selective attenuation by the atmosphere. • Skylight – That part of solar radiation that reaches the earth’s surface as a result of scattering in the atmosphere. Sunlight and skylight may therefore be considered as the direct and diffuse components of daylight.

7. Daylighting Daylight (both sunlight and skylight) is usually admitted into a building by the means of windows and skylights. The quantity of daylight obtained within a room will be dependent upon: • The orientation, geometry and space planning of the spaces to be lit. • The dimensions and orientation of the openings through which daylight will pass. • The location and surface properties of any internal partitions which may reflect and distribute the daylight. • The location, form and dimensions of any shading devices which will provide protection from too much light and glare. • The light and thermal characteristics of the glazing materials used. Types of openings [Adapted from: BRECSU, 1997] Rooflight Atrium Clerestorey Borrowed light Window

8. Controlling daylight A range of methods are available to control the amount of daylight that penetrates into the building. • Fixed external – Permanently obstructs skylight and is maintenance free, but is architecturally dominating. • Variable external – Allows the maximisation of skylight but can suffer from maintenance problems. • Variable internal – Absorbs solar radiation and acts as a secondary heat source within the building. Effective for visual comfort. Various methods of controlling daylight [Source London Metropolitan University, 2007]. In addition, further control can be provided by the choice of glazing type.

9. Daylight factor Interior daylight is measured using a parameter known as the Daylight Factor (DF). The daylight factor is defined as: The Daylight Factor is a combination of 3 separate components: • The sky component (SC) – the light received directly from the sky. • The externally reflected component (ERC) - the light received directly by reflection from buildings and obstructions outside the room. • The internally reflected component (IRC) - the light received from surfaces inside the room. DF = SC+ERC+IRC Estimates for the SC and ERC can be obtained from a number of sources, including: • BRE Daylight Protractors (BRE, 1990). • BRE Simplified Daylight Tables (BRE, 1990). • Waldrum Diagrams (BRE, 1990). • Fuller Moore Dot Charts (Moore, 1991). The IRC can be obtained from tabulated data (BRE, 1990).

10. Daylight factor Various corrections may be made to the daylight factor. These corrections take into account the following: • The deterioration of internal decorations. • Allowance for glazing frames and bars. • Glazing type. • Location. The recommended Daylight Factor in a room depends upon the type of activity taking place. Recommended Daylight Factors for various activities are given in BS 8206: Part 2: Code of practice for daylighting (BSI, 1992) and the CIBSE Code for Interior Lighting (CIBSE, 2002). However, as a general guide: Daylight factor Evaluation <2%Lighting will be mainly artificial. 2-5% Daylight a useful supplement. >5% Daylight dominates in daytime.

11. Daylight factor The distribution of daylight in a room is often shown by DF curves (or contours) which join points of equal Daylight Factor. The contours are generally shown on a plan of the room at working plane height, but can also be shown on a cross- section. Daylight Factor contours [Source: BRECSU, 1997 & Phillips, 2000]

12. Daylight factor The Daylight Factor may also be obtained from: • Architectural model studies. • Computer models. Radiance images and walkthrough [Source: Phillips, 2000 & Radiance, 2007]

13. Glare from daylight Glare is caused by one part of a room being excessively bright in relation to the remainder. It can be described in 2 ways: • Disability glare - when glare impairs vision, but does not necessarily cause discomfort. • Discomfort glare - when glare causes discomfort, but does not necessarily impair vision. Disability and discomfort glare can occur simultaneously or separately. Disability and discomfort glare [Source: CIBSE, 2002] Glare from daylight can be reduced by: • Using solar control devices - such as external screens and louvres, glass of low transmittance, or internal blinds and curtains • Other methods of decreasing the contrast between the interior and the view of the sky - such as ensuring that the window wall is light coloured.

14. Daylighting Duxford Solar Office. • Designed to eliminate the use of artificial light on normal days. • Average daylight factor of 2% over 80% of the office space. • Atrium has rooflights which allow natural light to enter the building. • PV façade designed to produce 25-33% of the offices electricity needs.

15. Daylighting BRE Environmental Building. • Designed to achieve a minimum 2% daylight factor over the office area. • Solar shading provided on South façade via motorised external translucent glass louvres.

16. Daylighting BRE Environmental Building. • Louvres made from 10mm clear-float glass, the undersides of which have a white ceramic coating to bounce daylight onto the internal troughed slab. • When external light level is low, louvres are opened so that they can act as external light shelves, reflecting daylight into the offices.

17. Innovative daylighting technologies A number of innovative daylighting technologies are available which are capable of redirecting the incoming sunlight or skylight to the areas where it is required. Mirror system The technologies available include: • Sunlight tracking systems - have mirrors and/or lenses that follow the sun and redirect its light to a required location. • heliostat and light pipe systems. • mirror systems. • Daylighting systems - redirect diffuse skylight and usually sunlight as well. They generally modify or supplement an existing window or rooflight. • light shelves. • prismatic glazing. • holographic diffracting systems. Prismatic glazing However, the performance of these technologies may be different from that expected and some of the technologies may be inappropriate for use in the UK.

18. Heliostat Mirror Light pipe Emitter Innovative daylighting technologies Light pipes Such systems attempt to redirect light deep into a building. They generally consist of 3 main elements: • Heliostat - a mirror which tracks the sun. • Light pipe - transfers light from the heliostat to the emitter. • Emitter - redirects the tracked sunlight to the space. Principles of a light pipe Light pipes can be expensive to construct and depend upon the sun shining. They often need to be supplemented by artificial lighting. Domestic SunPipe [Source: Monodraught, 2007]

19. Innovative daylighting technologies Mirror systems These systems are placed at the upper part of a window, and may or may not be set within the glazing system. Mirror system [Source: Okalux, 2007] Mirror systems protect occupants from high altitude direct sunlight and redirect low altitude direct sunlight onto the ceiling, which acts as a secondary diffuser. They can be difficult to maintain and tend to obstruct skylight. Mirrored louvre

20. Without light shelf External light shelf With light shelf No light shelf Internal light shelf Innovative daylighting technologies Light shelves These can be used to redirectsunlight and skylight deep into a space. Both interior and exterior light shelves are available. Exterior shelves can also function as a shading device. The performance of light shelves depends upon the proportion of the shelf which is situated inside or outside the space. Theycan also be used to control sunlight and reduce glare. Light shelf performance

21. Innovative daylighting technologies Prismatic glazingand holographic diffracting systems These systems utilise optical principles to redirect light into the space in question. They take 2 forms: • Glazing. • Films. Principle of prismatic glazing and film These systems can improve daylight penetration to the back of the room but only under limited conditions. Prismatic glazing can be used to limit glare.

22. Innovative daylighting technologies Innovative daylighting technologies are particularly appropriate where: • Visual requirements within the space are especially stringent, e.g. in a room with visual display units. • There are large external obstructions outside. • Much sunlight is available, typically in a south-facing window wall in a sunny location. • The space is too deep to give adequate uniformity of lighting with conventional windows. • Conventional windows or rooflights would give unacceptable, gloomy areas within a space.

23. Innovative daylighting technologies Sun-tracking heliostats at Manchester Airport [Source: Bomin Solar, 2007]

24. Innovative daylighting technologies Solar chandeliers at Manchester Airport [Source: Bomin Solar, 2007]

25. Innovative daylighting technologies Mirrored louvre system at Swanlea Secondary School, London [Source: Littlefair, 1996]

26. Innovative daylighting technologies Prismatic glazing incorporated into roof of Museum, Austria [Source: Bomin Solar, 2007]

27. Energy implications of daylighting To achieve good daylighting, the glazing must be designed so that there is a correct balance between the heat gains and losses resulting from the transmission of thermal radiation in and out of the building and the light entering the building. The energy implications of daylighting Correct daylighting design will not only reduce energy costs related to artificial lighting, but also reduce the possibility of having to cool rooms overheated by low efficiency lighting appliances. However, although large glazed areas may provide sufficient daylighting at some distance into the building, they can also cause glare, overheating and high heating and cooling energy costs. Daylight – Reduces artificial lighting load Solar gain – Reduces winter heating load Solar gain – Increase summer cooling load Conduction Convection Radiation Air leakage

28. Advantages of daylighting The utilisation of daylight in buildings has a number of advantages, namely: • It can make a significant contribution to energy efficiency. • It has a variability and subtlety which is more pleasing than the relatively monotonous environment produced by artificial lighting. • It helps to create optimum working conditions by bringing out the natural contrast and colour of objects. • Windows and skylights give occupants contact with the outside world. • The presence of natural light can bring a sense of well-being and awareness of the wider environment. • It is also claimed that exposure to natural light can have a beneficial effect on human health. However, due to its uncertainty and variability, daylighting cannot provide adequate illumination of the internal environment all of the time. Therefore, artificial lighting systems must always be incorporated into buildings in order to supplement daylighting when this is required.

29. Artificial lighting Artificial lighting can be used to: • Supplement daylighting. • Light rooms in a windowless environment. • Provide adequate illumination of buildings at night. Artificial lighting is constant and controllable, and can provide adequate illumination of the internal environmental all of the time.

30. Artificial lighting terminology The study of artificial lighting requires the use of a number of terms: • Luminous flux (F) - the amount of light emitted by a light source. Measured in lumens (lm). • Luminous efficacy - the luminous efficacy is the lamp light output in lumens per watt of electrical power consumption, (lm/W). The luminous efficacy of a lamp can fall by as much as 50% throughout its lifespan. • Luminous intensity (I) - is the power of a light source, or illuminated surface, to emit light in a particular direction. Measured in candelas (cd). • Illuminance (E) - the luminous flux density (spread of light) at a surface measured in lux (lx), where 1 lux = 1 lm/m2. A common minimum level for working is 200 lx, but in bright sunlight it can reach 50000lx. • Luminance (L) - this is a measure of the ability of an area of light source, or reflecting surface, to produce the sensation of brightness. • Colour rendering – this is the ability of a lamp to reveal the colour of a surface, compared to the colour of the surface viewed in daylight. The colour rendering index (Ra) gives a value of 100 for an ideal lamp, whilst practical lamps vary from 50 to 90.

31. Artificial lighting The quantity of light required in a room depends upon the type of activity taking place. Application Maintained illuminance (lux) Circulation areas, corridors 100 Stairs 150 Student common rooms and assembly halls 200 Classrooms, tutorial rooms 300 Lecture hall 500 Kitchen 500 Technical drawing rooms 750 Art rooms in art schools 750 Typical illuminance values for educational buildings [Source: CIBSE, 2002] Although the lighting requirement will be met by achieving the required illuminance on the working plane, the actual installed flux of the lighting system will be much greater. This is because not all of the installed flux will reach the working plane.

32. Artificial lighting Artificial lighting installations fall into 3 categories: • General lighting. • Localised lighting. • Local lighting. Each of these lighting installations can employ configurations of lamps, luminaires and control systems to provide the required illuminance.

33. General lighting General lighting These systems generally use a regular layout of luminaires to provide an approximately uniform illuminance over the whole working plane. General lighting system [Adapted from: CIBSE, 2002] Advantages: • Simple to plan. • Permit flexibility of task location. Disadvantages: • May be necessary to increase the number of luminaires if partitioning is installed. • Energy may be wasted in illuminating the entire area to the level required for the most critical tasks.

34. Localised lighting Localised lighting These systems are designed to provide the required maintained illuminance on work areas together with a lower illuminance for other areas. The lighting layout must be coordinated with the task positions and orientation. Localised lighting system [Adapted from: CIBSE, 2002] Advantages: • Normally consume less energy than general lighting systems. Disadvantages: • Can be inflexible. • Changes in layout can seriously impair the lighting system.

35. Local lighting General lighting system Local lighting These systems are designed to provide illumination only over the small area occupied by the task and its immediate surroundings. A general lighting system will also be installed to provide sufficient illumination for other areas. Local lighting system [Adapted from: CIBSE, 2002] Advantages: • Can be a very efficient method of providing adequate task illumination. • Most are accessible and adjustable. • Provides individual control. Disadvantages: • Must be positioned to minimise shadows, reflections and glare. • Although local luminaires allow efficient utilisation of emitted light, the lower wattage lamp circuits will be less efficient and the luminaires can be expensive.

36. Lamps Lamps A lamp is a light source (also known as a ‘bulb’). There are many different types of lamp available: Different types of lamp [Source: CIBSE, 1994] The most common lamps available can be categorised into a number of generic groups: • Filament. • Fluorescent. • High pressure discharge.

37. Lamps Filament These are the most common type of lamp. Light is produced by passing an electric current through a thin tungsten wire (filament), which heats up. The main groups are: • Incandescent tungsten filament and General Lighting Service (GLS) lamps. • Tungsten-halogen. Advantages and disadvantages of tungsten filament and tungsten halogen lamps [Source: Energy Saving Trust, 2004]

38. Lamps Fluorescent Fluorescent lamps work in a different way to incandescent lamps. The light output comes from phosphors which convert UV radiation from a low pressure mercury discharge into light. They have a tubular glass envelope. The main groups are: • Tubular fluorescent lamps. • Compact fluorescent lamps (CFLs). Advantages and disadvantages of tubular fluorescents and CFLs [Source: Energy Saving Trust, 2004]

39. Lamps High pressure discharge These consist of a small arc tube across which a discharge occurs at high pressure. The arc tube is surrounded by an outer envelope. They are not designed for frequent switching and are not normally used in dwellings. The main groups are: • High pressure sodium SON/E and SON/T lamps. • Metal halide lamps. Advantages and disadvantages of high pressure sodium and metal halide lamps [Source: Energy Saving Trust, 2004]

40. Lamps There are also significant differences in the efficiency and lamp life of different Lamps: • Compact fluorescent lamps (CFLs) are 3 to 5 times as efficient as incandescent lamps, with up to 10 times the lamp life (Leslie, 1993). • Full-size fluorescent lamps are 5 to 6 times as efficient and may last up to 20 times as long. • Energy savings from CFLs may not be as large as claimed, because most CFLs are much brighter seen from the side than from the ends, while a typical incandescent light is almost equally as bright from all directions. The choice of lamp will also affect the range of luminaires available and vice versa.

41. Lamps A number of factors should be taken into consideration when selecting a suitable lamp : • Lamp efficacy – the effectiveness of any lamp in transforming electricity into light. • Run-up time when switched on – some lamps have a time delay in providing illumination. • Colour-rendering – How accurately coloured surfaces appear under different light sources. • Colour temperature – An indication of the appearance of the light. • Dimming capability – Not all lamps can be dimmed successfully; it depends upon the control gear required to run the lamp. • Life and lumen maintenance characteristics – will vary for different lamp types. In addition, consideration should also be given to the types of luminaire available and the degree of light control and light output required.

42. Lamps Lamp chart [Source: Energy Saving Trust, 2004]

43. Luminaires This is the light fitting that holds or contains a lamp. It also redistributes the lamps luminous flux to achieve the required illuminance, so the choice of lamp must be combined with the choice of luminaire. There are 5 general types of luminaire: • Task/local luminaires. • Accent and display luminaires. • Uplight luminaires. • Wall-washing luminaires. • Downlight luminaires. Types of luminaire [Source: BRECSU, 1997] As well as containing the lamp, luminaires will also contain some or all of the following elements: • Reflector. • Optical control. • Screening elements. • Casing. • Control gear (lamp). • Luminaire control system. A luminaire [Source: BRECSU, 1997]

44. Glare from artificial lighting Glare can also be caused by artificial lighting. Artificial lighting glare is a function of: • The surface reflectances within the room. • The dimensions of the room. • How the lights are viewed (endwise or crosswise). The most common sources of disability and discomfort glare from artificial lighting relate to electric light sources seen directly or by reflection. Glare from artificial lighting can be reduced by: • The correct choice of luminaire layout and orientation. • The use of high reflectance surfaces for the ceiling and upper walls.

45. Artificial lighting controls One of the areas which can have a significant impact on the energy consumption of artificial lighting is the lighting controls. Lighting controls include: • Manual controls - allow areas to be controlled by particular switches. • Time controls - allow to be switched on or off automatically at set times of the day. Can be integrated into the BEMS. • Presence detectors - automatically switch lights on or off upon detection of movement or noise in an area. Important to have a built-in time delay to prevent lights switching off when area is still occupied. • Daylight detectors - allow groups of lights to be switched on or off according to the level of daylight. Some lights can also be dimmed or can ‘top-up’ as daylight levels alter. It is important that occupants havecontrol over their levels of lighting. Therefore, if automatic controls are used to turn lights on or off, occupants should be able to over- ride them using manual switches.

46. Energy consumption of artificial lighting The energy consumption of an artificial lighting system depends upon: • The efficiency of the various components of the system - the lamps, luminaires, and the control gear. • The balance between generalised or local lighting. • The way and number of hours in which the lighting system is used - this is often strongly influenced by the control system and the daylight availability. • The control system adopted. • The maintenance regime.

47. Energy efficient lighting Significant energy and cost savings can be made by increasing the use of energy efficient lighting. Electricity savings of almost 10 billion kWh (43PJ) could be achieved over a 10 year period, worth some £845 million. The savings in electricity use will result in CO2 emission reductions of over 900,000 tonnes of CO2 over the 10 year period. Energy and cost savings from energy efficient lighting [Source: Energy Saving Trust, 2004] These savings are based on the assumption that half of the rooms in around 750,000 dwellings are fitted with energy efficient lighting per year.

48. Lighting and the Building Regulations For new dwellings, guidance on fixed lighting is given in Approved Document L1A 2006 (ODPM, 2006a). ADL1A 2006 states that in all cases the Dwelling Emission Rate (DER) should be calculated using a fixed assumption of 30% low energy lighting. This means that low energy lighting provision is non-tradeable. The minimum amount of fixed energy efficient light fittings that should be provided is: • one per 25m2 of dwelling floor area (excluding garages) or part thereof; or • one per four fixed light fittings. A light fitting may contain one or more lamps. ADL1A 2006 also states that a way of showing compliance would be to provide light fittings (including lamps, control gear and an appropriate housing, reflector, shade or diffuser or other device for controlling output light) that only take lamps having a luminous efficacy greater than 40 lumens per circuit-Watt. Fluorescent and compact fluorescent lighting fittings would meet this standard. GLS or tungsten-halogenlamps would not. Guidance on fixed lighting in existing dwellings is given in Approved Document L1B 2006 (ODPM, 2006b).

49. Lighting and the Building Regulations For new non-domestic buildings, guidance on fixed and display lighting is given in Approved Document L2A 2006 (ODPM, 2006c). For general lighting in office, industrial and storage areas in all building types, ADL2A 2006 states that reasonable provision would be to provide lighting with an average initialefficacy of not less than 45 luminaire-lumens/circuit-Watt as averaged over the whole area of these types of space in the building. This allows design flexibility to vary the light output ratio of the luminaire and the luminous efficacy of the lamp. ADL2A 2006 also gives guidance on display lighting and controls in all types of space. Guidance on fixed and display lighting in existing non-domestic buildings is given in Approved Document L2B 2006 (ODPM, 2006d).

50. New lighting technologies In the domestic sector, the main focus to date has been on CFLs. CFLs are available as direct replacements for incandescent lamps which can be used in most existing luminaires. Control gear is required for CFLs. This is built-in on some lamps (CFLi). These lamps reach full output within a few seconds of switching on. CFLs are not suitable for dimming using standard domestic equipment, although specialist CFL-dimming equipment is available. Despite numerous subsidy programmes and the introduction of an energy label, the rise in CFL ownership has been slow. CFL ownership is estimated to be around 0.9 CFLs per household in 2000 (Boardman, Darby, Killip, Hinnells, Jardine, Palmer & Sinden, 2005).