Insulation. First Edition January Daylighting A WHITE PAPER. Low Energy Low Carbon Buildings

Transcription

1 Insulation First Edition January 2018 Daylighting A WHITE PAPER Low Energy Low Carbon Buildings

2 Contents Page Introduction 3 Executive summary 3 Definitions used in this white paper 3 Background 4 Daylight and health 4 Home satisfaction 4 Rights to light 4 Average daylight factor (ADF) 5 Building Research Establishment Environmental Assessment Method (BREEAM) 5 Analysis 7 Approach 7 Insulation 7 Façade build ups and U values 7 Façade layouts 8 Daylighting calculation software and room characteristics 8 Findings 9 Results 9 Conclusions 9 Appendices 10 Appendix A Façade layouts and room dimensions 10 Appendix B Results 12 References 14 2

3 Introduction Executive summary The amount of daylight building occupants have access to has an impact on their health and wellbeing, and so, has become an important consideration in building design. Daylighting calculations measure the average daylight factor (ADF) for different habitable rooms and recommended ADF criteria is outlined in recognised industry standards and assessment criteria, such as BS : 2008 (Lighting for buildings. Code of practice for daylighting) and Building Research Establishment Environmental Assessment Method (BREEAM) criteria. Peutz BV carried out daylighting calculations to assess the difference in the ADF of a room when utilising Kingspan Kooltherm K15 Rainscreen Board compared to mineral fibre insulation within external wall façade build ups that achieve three different U-values for each insulation type: 0.11 W/m².K; 0.15 W/m².K; and 0.21 W/m².K, incorporating four different façade layouts. Results from the research included high ADFs (the highest being %) for the room with external wall façade build ups utilising Kingspan Kooltherm K15 Rainscreen Board. The percentage of improvement in ADF for the room with external wall façade build ups utilising Kingspan Kooltherm K15 Rainscreen Board compared to mineral fibre insulation, for all U-values and façade layouts, ranged between 10.6 % 63.2 %. All results incorporating Kingspan Kooltherm K15 Rainscreen Board exceeded the minimum daylighting criteria from BS : 2008 for bedrooms and living rooms. Definitions used in this white paper Daylighting the practice of installing windows, or other openings, and reflective surfaces within buildings to allow natural daylight to enter rooms and internal spaces to maximise visual comfort, which contributes positively to health and wellbeing, alongside other benefits. Easement a right that benefits one property owner but disadvantages another, such as the right to walk over the land of a neighbouring property to enter your own. Working plane a horizontal level positioned at the working height of an internal space. CIE standard overcast sky the International Commission on Illumination (CIE) defines universal outdoor daylight conditions via mathematical formulation in BS ISO 15469: 2004 (Spatial distribution of daylight. CIE standard general sky). Average daylight factor (ADF) the ratio of total daylight flux incident on the working plane to the area of the working plane, expressed as a percentage of the outdoor illuminance on a horizontal plane due to an unobstructed CIE standard overcast sky. Thus a 1 % ADF would mean that the average indoor illuminance would be one hundredth the outdoor unobstructed illuminance, (Littlefair, 2011). A number of conclusions were derived from the results, such as windows are best positioned above the working plane to allow an optimum amount of natural light to enter a room. Also, Kingspan Kooltherm K15 Rainscreen Board offers a thin insulation solution to meet or exceed the minimum daylighting requirements set out in BS : 2008 more efficiently and effectively, and offers a way to achieve BREEAM visual comfort daylighting credits with relative ease, compared to mineral fibre insulation. Therefore, installing Kingspan Kooltherm K15 Rainscreen Board can assist in keeping window reveal depths to a minimum to allow entry of more natural light into buildings whilst also achieving or exceeding thermal requirements. The additional natural light entering habitable rooms from installing Kingspan Kooltherm K15 Rainscreen Board should have a positive impact on the health and wellbeing of occupants, especially those who spend a lot of time indoors during the day. 3

4 Background Daylight and health BS : 2008 highlights how access to daylight is important for health and wellbeing. For example, the circadian system controls seasonal and daily body rhythms and links different functions of the body, such as sleeping and waking cycles and core body temperature changes, with the external day and night cycle. Lack of access to natural light can disrupt the circadian system and cause health problems, such as sleep deprivation and depression. Symptoms of Seasonal Affective Disorder (SAD), such as depression, low energy, tiredness, increased appetite and weight gain, all of which are typical in winter, can be reduced with exposure to daylight. Excessive amounts of ultraviolet (UV) radiation are considered damaging to the skin, but a sufficient level of exposure to daylight is needed to maintain healthy levels of vitamin D. Vitamin D deficiency can lead to rickets in children and bone softening in adults. Exposure to sunlight can also kill many types of bacteria and virus, particularly in winter when there is an increased amount of respiratory infections. Therefore, building occupants require access to adequate levels of daylight, particularly those who are of limited mobility and spend a lot of time indoors, such as those in hospitals and nursing homes, to prevent health problems and a negative impact on mood. Home satisfaction The Royal Institute of British Architects (RIBA) commissioned Ipsos MORI to complete a survey in 2013 to find out whether people were satisfied with their homes. The main causes of dissatisfaction within people s homes were high energy bills (49 %), lack of space (32 %) and lack of natural light (20 %), outweighing access to amenities, work and schools. Those that showed the most dissatisfaction were those in newer homes. People living in homes 10 years old or less were most likely to consider modifying their homes or moving. The survey results were interpreted to suggest that the public want the Government to regulate and ensure that new homes are built to meet sufficient standards, such as minimum daylighting requirements to allow the entry of natural light. Rights to light The Law Commission proposed a reform to an existing easement called Rights to Light in 2014 that provides landowners the right to receive natural light through windows, and other openings, in their buildings. This easement burdens a landowner by disallowing them to build in a way that blocks light without the consent of the neighbouring landowner benefiting from natural light entering their building. However, the easement is valuable as it gives landowners certainty that they will have continued enjoyment of natural light, increasing their property s utility, desirability and value. The Law Commission are currently awaiting a response to their recommendations from the Government. 4

5 Average daylight factor (ADF) Simply put, a daylight factor is the ratio between the level of light inside a building to the level of light outside a building. BR 209 (Site Layout Planning for Daylight and Sunlight: A Guide to Good Practice) defines an average daylight factor (ADF) as the ratio of total daylight flux incident on the working plane to the area of the working plane, expressed as a percentage of the outdoor illuminance on a horizontal plane due to an unobstructed CIE standard overcast sky. Thus a 1 % ADF would mean that the average indoor illuminance would be one hundredth the outdoor unobstructed illuminance, (Littlefair, 2011). There is a general rule consensus of 2 % being the ADF designers should aim for, for rooms to appear sufficiently day lit, according to ARUP and the UK Green Building Council s technical paper (Healthy Homes: Daylight and Sunlight), CIBSE LG10 (Lighting for the Built Environment. Daylighting: a Guide for Designers) and BS : BS : 2008 highlights that it is good practice to ensure rooms within buildings have a predominantly day lit appearance and to achieve this, ADFs should be at least 2 %. A room that has an ADF of 5 % is considered well day lit. Table 1 shows the minimum ADF for particular rooms in dwellings taken from BS : Room type Minimum ADF Bedroom 1 % Living room 1.5 % Kitchen 2 % Table 1: Minimum ADFs for dwellings taken from BS : However, BR 209 suggests that interiors with high ADFs of over 6 % are more likely to have problems with overheating during summer and excessive heat loss in winter. So, ideally ADFs should range between 2 5 % for good daylight provision. Building Research Establishment Environmental Assessment Method (BREEAM) Part of the BREEAM criteria for buildings is visual comfort, which is split into four parts with a respective number of credits available: l glare control, which has one credit available; l daylighting, which has up to two credits available depending on the building type; l view out, which has one credit available, with the exception of healthcare buildings with inpatient areas having two credits available; and l internal and external lighting, which has one credit available. The first credit for daylighting concerns maintaining good daylighting in an existing dwelling being refurbished or converted, and achieving minimum daylighting requirements in a dwelling extension. The second credit concerns achieving minimum daylighting requirements in a dwelling as a whole. The daylighting credits can be achieved by producing daylighting calculations that follow the minimum ADFs outlined in BS : 2008 for kitchens (2 %), living rooms, dining rooms and studies (1.5 %). For refurbished or converted dwellings, all relevant questions in Appendix A: Hea 01 must be answered no. Extensions must also not significantly reduce daylighting levels in the aforementioned rooms of neighbouring properties, with angular calculations on the site plan and elevations between the properties needed to prove this. Also, 80 % of the working plane in each of the particular rooms needs to receive direct light from the sky. Evidently, access to natural light is important for health and wellbeing, and home satisfaction. It also has significant implications in building design. In order to achieve or exceed minimum daylighting requirements, such as those outlined in BS : 2008, and to subsequently obtain BREEAM credits, one key aspect of the building design process is window layout (quantity, size and location). 5

6 Background Careful consideration is needed to achieve an adequate level of daylighting via windows, or other openings, whilst not compromising thermal U-value requirements outlined in Approved Documents L1A, L1B, L2A and L2B for England and Wales and Technical Handbooks Domestic and Non domestic Section 6 Energy for Scotland to meet Building Regulations, among other concerns, such as structural analysis. This white paper investigates the use of Kingspan Kooltherm K15 Rainscreen Board compared to mineral fibre insulation in a number of scenarios with differing conditions such as, overall U values achieved in external wall façade build ups and different façade layouts, to find the optimum solutions to meet and exceed daylighting and thermal requirements. A certain amount of insulation is required to achieve or exceed the recommended minimum U values in the aforementioned documents to meet Building Regulations. However, the more windows and openings there are in a building, the thicker the insulation will need to be to minimise thermal bridging and heat loss. This may have a negative impact on window reveal depths, so a thin insulation solution is needed to reduce this. 6

7 Analysis Approach Kingspan Insulation Ltd. commissioned Peutz BV to carry out daylighting calculations to assess the difference in the ADF of a room utilising Kingspan Kooltherm K15 Rainscreen Board compared to mineral fibre insulation within external wall façade build ups. Insulation The two types of insulation compared were Kingspan Kooltherm K15 Rainscreen Board, a foil faced rigid phenolic insulation with a lambda value of W/m.K, and mineral fibre insulation with a lambda value of W/m.K. U value calculations were carried out by Kingspan Insulation Ltd. comprising external wall façade build ups of 200 mm thick concrete, thermal insulation (Kingspan Kooltherm K15 Rainscreen Board or mineral fibre insulation), a ventilated cladding zone of 50 mm and 6 mm thick rainscreen cladding. The thermal resistance of the insulation fasteners and ventilated air cavity were less than 3 % of the total U values. Also, a rainscreen cladding bracket correction of W/m².K was taken into account in each U value calculation. The external wall façade build ups are highlighted in Figures 1 and 2 below. Façade build ups and U values 0.11 W/m².K, 0.15 W/m².K, and 0.21 W/m².K were the three U values considered, which meet or exceed recommended best starting point fabric U values for external walls of domestic and non domestic buildings in England, Wales and Scotland, which are highlighted in Table 2. Domestic new build external wall U value (W/m 2. K) Non domestic new build external wall U value (W/m 2. K) England Wales Scotland Table 2: Best starting point (fabric) recommended U values for England, Wales and Scotland. Rainscreen cladding Ventilated cladding zone Kingspan Kooltherm K15 Rainscreen Board 200 mm concrete Figure 1: External wall rainscreen façade build up incorporating Kingspan Kooltherm K15 Rainscreen Board. Rainscreen cladding 200 mm concrete Ventilated cladding zone Rock mineral fibre Figure 2: External wall rainscreen façade build up incorporating mineral fibre insulation. 7

8 Analysis Façade layouts Four different façade layouts were taken into account for each external wall façade build up and U value, depicted in Appendix A, Figures 3 6. Daylighting calculation software and room characteristics DIALux evo 6 software calculated the ADF in a room for each external wall façade build up and façade layout. The luminance distribution of the CIE standard overcast sky was taken into account. The calculation plane was positioned at 0.7 m above ground level with the exclusion of a border zone of 0.5 m from the walls. BR 209 and BS : 2008 advise a horizontal plane at 0.7 m above ground level should be taken into account for offices and 0.85 m for dwellings. The internal room dimensions were 5 m width x 3.5 m depth x 2.8 m height, depicted in Appendix A, Figure 7. The internal light reflective properties of the room were 30 % for the floor (dark grey carpet), 70 % for the walls (light grey paint) and 80 % for the ceiling (white paint). No other buildings or obstructions, or furniture, were taken into account. 8

9 Findings Results Table 3 and Figure 8 in Appendix B show the ADF results. The key findings from the research are highlighted below. l The highest ADFs were from façade layout 1 (a single wide spanning window with dimensions of 4 m x 1.25 m, positioned above the working plane). l The highest ADF was % from façade layout 1 with the external wall façade build up achieving 0.21 W/m².K utilising Kingspan Kooltherm K15 Rainscreen Board. l The percentage of improvement in ADFs from external wall façade build ups utilising Kingspan Kooltherm K15 Rainscreen Board compared to mineral fibre insulation, for all façade layouts, ranged between 10.6 % 63.2 %. l The greatest percentage of improvement in ADFs from external wall façade build ups utilising Kingspan Kooltherm K15 Rainscreen Board compared to mineral fibre insulation were from façade layout 2 (four windows with dimensions of 1.25 m x 0.75 m, positioned above the working plane), ranging between 18.1 % 63.2 %. l All results incorporating Kingspan Kooltherm K15 Rainscreen Board exceeded the minimum daylighting criteria from BS : 2008 for bedrooms and living rooms. Only one result incorporating Kingspan Kooltherm K15 Rainscreen Board fell marginally short for kitchens, with an ADF of % in façade layout 2. Conclusions A number of conclusions can be drawn from these results, such as windows are best positioned above the working plane to allow an optimum amount of natural light to enter a room. Also, a single wide spanning window positioned above the working plane, compared to having numerous windows of a narrower width placed above or below the working plane, is more beneficial to allow an optimum amount of natural light to enter a room. Kingspan Kooltherm K15 Rainscreen Board offers a thin insulation solution to meet or exceed the minimum daylighting requirements set out in BS : 2008 more efficiently and effectively compared to mineral fibre insulation. Kingspan Kooltherm K15 Rainscreen Board also offers a way to achieve BREEAM visual comfort daylighting credits with relative ease compared to mineral fibre insulation. This has been demonstrated by external wall facade build ups insulated with Kingspan Kooltherm K15 Rainscreen Board, achieving the same U values as those with mineral fibre insulation, with differing façade layouts, achieving the highest ADFs for a room, with up to 63.2 % improvement compared to mineral fibre insulation. Therefore, installing Kingspan Kooltherm K15 Rainscreen Board can assist in keeping window reveal depths to a minimum to allow entry of more natural light into buildings whilst also achieving or exceeding thermal requirements. The additional natural light entering habitable rooms from installing Kingspan Kooltherm K15 Rainscreen Board should have a positive impact on the health and wellbeing of occupants, especially those who spend a lot of time indoors during the day. 9

10 Appendices Appendix A Façade layouts and room dimensions 1.25 m 4.00 m 1.35 m 2.80 m 5.00 m Figure 3: Façade layout m 0.75 m 2.80 m 1.35 m 5.00 m Figure 4: Façade layout m 2.80 m 0.70 m 5.00 m 1.25 m Figure 5: Façade layout 3. 10

11 Height: 2.80 m 1.90 m 2.80 m 0.70 m 5.00 m 0.70 m Figure 6: Façade layout 4. Room depth: 3.50 m Façade width: 5.00 m Figure 7: Room dimensions. 11

12 Appendices Appendix B Results Façade layout U-value of external wall build up (W/m².K) ADF with mineral fibre insulation (%) ADF with Kingspan Kooltherm K15 Rainscreen Board (%) Percentage of improvement using Kingspan Kooltherm K15 Rainscreen Board instead of mineral fibre insulation (%) m 4.00 m 2.80 m 5.00 m m 1.35 m 0.75 m 2.80 m 5.00 m m 2.80 m 1.35 m 0.70 m 1.25 m 5.00 m m 0.70 m 2.80 m 0.70 m 5.00 m Table 3: Results of the daylighting research. 12

13 70.00 % % % Percentage of improvement in ADF using Kingspan Kooltherm K15 Rainscreen Board % % Façade Layout 1 Façade Layout 2 Façade Layout 3 Façade Layout % % 0.00 % 0.21 W/m 2. K 0.15 W/m 2. K 0.11 W/m 2. K U value Figure 8: Percentage of improvement in ADF using Kingspan Kooltherm K15 Rainscreen Board. 13

14 References Antonutto, G. (2017) Healthy Homes: Daylight and Sunlight Technical Paper, London: ARUP and UK Green Building Council. Available at: files/08459%20ukgbc-arup%20daylighting%20final.pdf [Accessed 22nd September 2017]. BRE Global (2014) BREEAM Refurbishment Domestic Buildings SD5072 Issue 3.2 Hea 01 Daylighting, BRE Global. Available at: content/05hea/hea_01_daylighting.htm [Accessed 22nd September 2017]. BRE Global (2014) BREEAM UK New Construction Non- Domestic Buildings Technical Manual SD5076 Issue 5 Hea 01 Visual Comfort, BRE Global. Available at: com/breeamuk2014schemedocument/content/05_health/ hea01_nc.htm [Accessed 22nd September 2017]. British Standards Institution (2008) Lighting for buildings Part 2: Code of practice for daylighting, London: BSI. Available at: ProductDetail/?pid= [Accessed 22nd September 2017]. British Standards Institution (2004) Spatial distribution of daylight. CIE standard general sky, London: BSI. Available at: ProductDetail/?pid= [Accessed 22nd September 2017]. Charted Institution of Building Services Engineers / The Society of Light and Lighting (2014) Lighting for the built environment CIBSE LG10: Daylighting a guide for designers, Norwich: Page Bros. Available at: knowledge-items/detail?id=a0q i7kkaas [Accessed 22nd September 2017]. Department for Communities and Local Government (2014) Approved Document L1A: conservation of fuel and power in new dwellings, National Building Specification (NBS). Available at: attachment_data/file/540326/br_pdf_ad L1A 2013_ with_2016_amendments.pdf [Accessed 22nd September 2017]. Department for Communities and Local Government (2014) Approved Document L2A: conservation of fuel and power in new buildings other than dwellings, National Building Specification (NBS). Available at: government/uploads/system/uploads/attachment_data/ file/540328/br_pdf_ad_l2a_2013_with_2016_amendments. pdf [Accessed 22nd September 2017]. Department for Communities and Local Government (2015) Approved Document L2B: conservation of fuel and power in existing buildings other than dwellings, National Building Specification (NBS). Available at: government/uploads/system/uploads/attachment_data/ file/540329/br_pdf_ad_l2b_2013_with_2016_amendments. pdf [Accessed 22nd September 2017]. Ipsos MORI / RIBA (2013) Housing Standards and Satisfaction: What the Public Wants, London: Ipsos MORI. Law Commission (2014) Rights to Light, London: OGL. Available at: uploads/attachment_data/file/391683/44872_hc_796_law_ Commission_356_WEB.pdf [Accessed 22nd September 2017]. Littlefair, P. (2011) BR 209: Site Layout Planning for Daylight and Sunlight: A Guide to Good Practice, 2nd edition, Watford: IHS BRE Press. Scottish Government (2017) Technical Handbooks: Domestic Section 6 Energy. Available at: Resource/0052/ pdf [Accessed 22nd September 2017]. Scottish Government (2017) Technical Handbooks: Non- Domestic Section 6 Energy. Available at: Resource/0052/ pdf [Accessed 22nd September 2017]. Staut, D. (2017) Research regarding daylighting: Daylighting in relation to façade insulation with Kooltherm K15, Kooltherm K115 or mineral wool, Zoetermeer: Peutz. Department for Communities and Local Government (2015) Approved Document L1B: conservation of fuel and power in existing dwellings, National Building Specification (NBS). Available at: system/uploads/attachment_data/file/540327/br PDF AD_L1B_2013_with_2016_amendments.pdf [Accessed 22nd September 2017]. 14

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