Insulation for Education - Part 2: Guidance on Thermal Comfort and Daylighting in the Learning Environment - Kingspan Insulation
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Welcome to Part 2 of this two part CPD video on insulation for education guidance for thermal comfort and daylighting in the learning environment.
Part 1 Content Summary
In part one of this two part CPD video we covered; the requirements of building bulletin BB101 guidelines on ventilation thermal comfort indoor air quality in schools; the thermal comfort recommendations in schools and how to meet building regulations part L; the effects thermal comfort can have on both the learner and educator in a learning environment; and how to improve air tightness and reduce thermal bridging.
Content Part 2
In Part 2 we'll now cover:
- Daylighting and the impact on health will being and performance
- Insulation solutions to meet the thermal comfort and daylighting requirements within an education building
- The requirements of building bulletin BB100 designed for fire safety in schools
- Case studies showing practical examples of how effective use of insulation can be achieved in various learning environments
As well as space heating another opportunity for energy savings is lighting. Well-lit spaces are essential for an effective teaching and learning environment as a result lighting accounts for approximately 10% of the total energy used in schools. Lighting is one of the greatest single sources of electrical energy consumption, on average 20% of the world's electricity is used in artificial lighting. So, lighting offers an ideal opportunity to significantly improve building energy efficiency.
But what is the greatest natural source of light and energy?
Harnessing the sun can help reduce energy consumption but the amount of daylight building occupants have access to has an impact on their health and well-being and creating good appearance for workspaces and environments.
So, what is daylighting daylighting is 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 well-being alongside other benefits. Document BS 8206-2: 2008 lighting for buildings code of practice with daylighting gives recommendations regarding the design for daylighting in buildings.
Impact on Health and Performance of Students
Similarly, to the effects of thermal comfort daylight is essential for health and well-being daylight exposure will boost your ability to sleep at night, as well as your mood and alertness during daylight.No electric light even high quality LED can entirely correctly replicate the frequency of visible light or achieve the variation that we perceive at different times of the day or throughout the year.
Guidance from both the Education Funding Agency EFA and chartered institution of building service engineers CIBSE, suggests that natural daylighting should be the primary source of light within education spaces. There is a clear operational advantage to this strategy. By providing improved levels of daylight it is possible to reduce reliance on artificial lighting minimising energy demand and long term running costs.
However, the advantages of improved daylighting extend far beyond energy efficiency our circadian rhythm or body clock is linked to the daily cycle of the sun. It produces melatonin that is essential for the body to function and boosts our ability to rest and improves our mood and alertness. Natural light helps to reinforce arcadian rhythm making us more alert during the day and improving our sleep at night. Studies have shown that young people are particularly sensitive to disruptions to this rhythm, as a result of their smaller pupillary sizes and weaker melatonin suppression. The arcadian system control seasonal and daily body rhythms and links different functions of the body temperature changes with the external day and night cycle.
Lack of access to natural light can disrupt occur arcadian system and cause health problems such as, sleep deprivation and depression. Natural light can also make it simpler for students to see understand and retain learning materials, mental function and memory is 10 to 25% better with outside views. It is more diffuse than typical artificial ceiling lights providing better illumination through outer space. It also contains the full spectrum of colour wavelengths visible to the human eye, allowing improved colour rendition. Additionally, it avoids potential problems associated with some artificial lights such as flickering, which can cause headaches and eye strain.
Research has shown that as a result of these factors provision of good quality natural light can have a notable impact on student attainment. A study of over 21,000 US students in 1999 showed that those with the most daylight in their classrooms progressed 20% faster on maths tests and 26% faster on reading tests in one year than those with the least.
A further study of 71 elementary schools provided additional evidence that good lighting provision both from natural and artificial sources significantly influenced pupils reading vocabulary and science test scores.
Daylighting can also aid in reducing absenteeism due to illness 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 to prevent health problems and a negative impact on mood.
Access to natural light is particularly important for young people as such when designing education spaces, it is important to carefully consider all factors which can impact daylighting, including the insulation specification.
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 8206 part 2 2008, lighting for buildings, code of practice for daylighting and, building research establishment environmental assessment method BREEAM criteria.
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 illuminant’s on a horizontal plane due to an un-obstructive CIE standard overcast Sky. Thus, 1% ADF would mean that the average indoor illuminants would be 100th the outdoor unobstructed illuminants Little Fair 2011. Put simply it is the ratio between the level of light inside a building to the level of light outside a building.
There is a general rule consensus of 2% being the ADF designer should aim for, for rooms to appear sufficiently daylight according to Arup and the UK green building councils’ technical paper healthy homes daylight and sunlight. CIBSE LG10 lighting for the built environment daylighting a guide for designers and BS 8206 part 2: 2008.
BS 8206 part two 2008 highlights that it is good practice to ensure rooms within buildings have a predominantly daylit appearance and to achieve this ADFs should be at least 2%. A room that has an ADF of 5% is considered well daylit.
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 ADF should range between 2 and 5% for good daylight provision.
Whilst daylighting design tends to focus on the size and positioning of fenestration, the thickness of wool constructions can also have a significant impact on light entering through windows. Recent research has shown that by installing phenolic insulation instead of low performing materials, it is possible to keep both external wall and window reveal depths to a minimum. Allowing natural light levels to be enhanced with a thermally efficient construction but we will explore this research it later on in this video.
BREEAM: Visual Comfort
A part of the BREEAM criteria for buildings is visual comfort, which is split into four parts with the respective number of credits available.
- Glare control, 1 credit available.
- Daylighting, up to 2 credits available depending on the building type.
- View out, 1 credit is available with the exception of healthcare buildings with inpatient areas having 2 credits available.
- Internal and external lighting, 1 credit available.
Access to natural light is important for health and well-being. It also has significant implications in building design, in order to achieve or exceed minimum daylighting requirements such as those outlined in BS8 206 Part 2 2008 and to subsequently obtain BREEAM credits.
BREEAM - Daylighting
Here are the daylighting requirements for BREEAM. Other requirements either A or B & C.
A - a uniformity ratio of at least 0.4 or a minimum point daylight factor of at least 0. 8%. Spaces with glazed roofs such as Atria must achieve a uniformity ratio of at least 0.7 or a minimum point daylight factor of at least 1.4%. Due to particular lighting issues in teaching spaces the uniformity ratio can be reduced to 0.3 as defined in BB87 environmental design standard. This deviation from the criteria can only be considered in circumstances where BB87 applicable. A uniformity ratio of at least 0.4 or a minimum point daylight factor of at least 0.4 times the relevant average daylight factor value in table 5.1.
Spaces with glazed roofs such as Atria must have a minimum point daylight factor of at least 0.7 times the relevant average daylight factor value in table 5.1.
Spaces with glazed roof such as Atria must achieve a uniformity ratio of at least 0.7 or minimum point daylight factor of at least 1.4%.
Or B, a view of sky from desk height 0.7m is achieved.
And C, the room depth criterion room depth divided by room width plus, room depth divided by window head height from floor level is less than 2 divided by 1 minus the average reflectance of surface is in the rear half of the room, is satisfied.
Insulation and Daylighting
The amount of daylight building occupants have access to has an impact on their health and well-being and so has become an important consideration in building design.
There are several design considerations for daylighting provision including: window size, quantity and layout: room layout and depth; internal finishes, such as reflective surfaces and interior decoration; and positioning of exterior obstructions, such as other buildings or trees.
Insulation Solutions - Wall
To find out more, Peutz BV were commissioned to carry out a detailed report assessing how different insulated constructions could impact daylighting within a room.
Peutz BV carried out daylighting calculations to assess the difference in the ADF a room comparing a premium performance for phenolic insulation for behind the rain screen cladding system with a thermal conductivity of 0.0201 watts square metre Kelvin to a mineral fibre insulation of 0.035 Watts per meter Kelvin.
These products were used within external wall facade build-ups to achieve 3 different U-values for each insulation type.
- 0.11 Watts per square meter Kelvin
- 0.15 Watts per square metre Kelvin
- 0.21 watts per square metre Kelvin
Incorporating four different facade layouts. As well as comparing phenolic insulation for behind the rain screen cladding system with that of rock mineral fibre insulation. Peutz BV have also carried out daylighting calculations to assess the difference in the ADF of a room when utilising phenolic insulation for use in a cavity wall. A U-value of 0.17 watts per square metre Kelvin was considered when comparing the rigid phenolic insulation with a Lambda value of 0.018 watts per meter Kelvin faced, on one side with a low emissivity composite foil and faced on the other side with a watertight vapour open Polypropylene fleece with the mineral fibre insulation with a Lambda value of 0.035 watts per meter Kelvin.
Insulation Solutions - Rainscreen
There is a general rule consensus of 2% being the ADF designers should aim for, for rooms to appear sufficiently daylit a room that has an ADF of 5% is considered well daylight. So ideally, ADF should range between 2 and 5% for good daylight provision.
On screen you can see the results of the daylighting research with facade build up incorporating phenolic insulation for use behind the rain screen cladding system 0.020 Watts per meter Kelvin and the percentage increase when compared to the ADF of mineral fibre insulation 0.035 watts per meter Kelvin.
Here you can see the results of the second 2 facade layouts.
Peutz BV Research
The research produced a number of clear and compelling results. The tested constructions and facade layout speech ring the phenolic insulation board, had a higher ADF than those with mineral fibre, the percentage of improvement in the relative ADFs ranged between 10.6% and 63.2% for the rain screen build-ups. For the cavity wall build up the percentage of improvement in ADFs ranged between 13.7% and 23. 2%.
The reduced external wall thickness by incorporating the phenolic insulation board, helped to improve the ADF. These phenolic insulation boards also offers a way to achieve BREEAM visual comfort daylighting credits with relative ease, compared to mineral fibre insulation. This has been demonstrated by wall build-ups for both facades and cavity walls insulated with these insulation boards achieving the same U-values as those with mineral fibre insulation with differing facade layouts achieving the highest ADFs for a room with up to 63.2% improvement compared to mineral fibre insulation. Therefore, installing phenolic insulation board 0.0201 square metre Kelvin 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 this insulation 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. However, as the saying goes too much of a good thing....
BR 209 suggests that interiors with high ADF SUV over 6% are more likely to have problems with overheating during summer, due to solar gain and excessive heat loss in winter. Therefore, it is important to remember that ADF should ideally be between 2 and 5%.
Insulation Solutions - Floor
When specifying insulation, it is important to consider both the thermal comfort and daylighting requirements within an educational building. We have run number of U-value calculations to compare some of the insulation products available in the market today.
When comparing a vacuum insulation flooring system with a Lambda value of 0.007 watts per meter Kelvin and a rock mineral fibre insulation with a Lambda value of 0.035 Watts per meter Kelvin in a beamer block ground floor application. 40mm of VIP vacuum insulation panels insulation achieved a U-value of 0.15 watts per square metre Kelvin.Whereas a 40mm rock metal fibre only achieved 0.28 watts per square metre Kelvin. In order to achieve the 0.15 Watts per square metre Kelvin U-value that 40mm of VIP insulation does, you would need 140mm of rock mineral fibre.
This shows that in order to meet the stringent requirements of BB101 with regards to thermal comfort, using the higher performing vacuum insulation material means it is easier to meet the U-values required with a thinner construction.
Insulation Solutions - Roof
In a roof application we compared a PIR insulation board with Lambda value of 0.022 watts per meter Kelvin with a rock mineral fibre insulation board with a Lambda value of 0.035 watts per metre Kelvin, in a concrete deck suspended ceiling application.
125mm of PIR insulation are U-value of 0.16 watts per square metre Kelvin, whereas it takes 195mm of rock mineral fibre insulation.
125mm of rock mineral fibre insulation achieves a U-value of only 0.25 watts per square metre kelvin.
As we can see, by fitting insulation materials with better thermal conductivities it is possible to minimise the construction thickness and weight required to achieve the desired thermal performance for that element, U-value.
Building Bulletin 100 (BB100: Design for Fire Safety in Schools)
Whilst this video is focused on thermal comfort and ADF of education in buildings, another important factor to be considered is the fire performance of the building materials and the fire safety of the building. Building bulletin 100 BB100, designed with fire safety in schools provides fire safety design guidance for schools in England and Wales. The guidance applies to nursery schools, primary and secondary schools, including sixth form colleges, academies and city technology colleges, special schools and pupil referral units, What is not is not covered in BB10, sixth form college designated as institutions of further education are covered by approved document B ADB buildings which include residential accommodation, buildings with the top floor higher than 18 metres, buildings with the basement deeper than 10 metres and car parks including those as part of the school building, for more requirements for life safety are covered by national legislation for building regulations and supporting technical guidance with respect to fire. The current BB100 is largely based on approved document B fire safety to the building regulations.
On screen you can see the functional requirements for the internal and external fire spread from BB10 6.1.1 internal fire spread:
- The building should be designed and constructed so that in the effective fire its stability will be maintained for a reasonable period.
- A wall common to two or more buildings shall be designed and constructed so that it adequately resists the spread of fire between those buildings.
- Where reasonably necessary to inhibit the spread of fire within the building, measures shall be taken, to an extent appropriate to the size and intended use of the building, comprising either or both of the following:
- A - subdivision of the building with fire resistant construction; and
- B - installation of suitable automatic fire suppression systems.
- The building shall be designed and constructed so that the unseen spread of fire and smoke within concealed spaces in its structure and fabric is inhibited.
7.1.1 external fire spread:1, the external walls of the building shall adequately resist the spread of fire over the walls and from one building to another, having regard to the height use and position of the building.
A concealed space cavity in the external wall of a building can act as a chimney and provide an easy route for flame, hot gases and smoke to propagate from one compartment of a building to another.
Cavity barriers are used to close concealed spaces and prevent penetration of smoke or flame to restrict the movement of fire within a building. In BB100 provisions for cavity barriers are given for specified locations. The provisions necessary to restrict the spread of smoke and flames through cavities are broadly for the purpose of subdividing:
- A - cavities which could otherwise former pathway around the fire separating element and closing the edges of cavities. Therefore, reducing the potential for unseen fire spread. Please note these should not be confused with fire stopping details.
- B - extensive cavities.
Consideration should also be given to the construction and fixing of cavity barriers provided for these purposes and the extent to which openings in them should be protected. Cavity barriers should be provided to close the edges of cavities, including around openings.
Cavity barriers should also be provided at the junction between an external cavity wall, except where the cavity wall complies with figure 31 in BB100 and every compartment floor and compartment wall and, at the junction between an internal cavity wall except where the cavity wall complies with figure 31 and every compartment floor, compartment wall or other wall or door assembly which forms a fire resisting barrier.
It is important to continue any compartment wall up through a ceiling or roof cavity to maintain the standard of fire resistance. Therefore, compartment walls should be carried out full story height into a compartment floor or to the roof as appropriate. It is therefore not appropriate to complete a line of compartmentation by fitting cavity barriers above them.
Maximum dimensions of cavities
Table 10 from BB100 onscreen sets out maximum dimensions for undivided concealed spaces with some exceptions extensive concealed spaces should be subdivided to comply with the dimensions in this table.
The provisions in table 10 do not apply to any cavity:
- A - in a wall which should be fire resisting only because it is load bearing.
- B - in a masonry or concrete external cavity wall shown in figure 31.
- C - in any floor or roof cavity above a fire resisting ceiling as shown in figure 32 and which extends throughout the building or compartment subject to a 30 metre limit on the extent of the cavity.
- D - formed behind the external skin of an external cladding system with a masonry or concrete in a leaf at least 75mm thick or by overcladding an existing masonry or concrete external wall or an existing concrete roof provided that the cavity does not contain combustible insulation.
- E - double skinned corrugated or profiled insulated roof sheeting, if the sheeting is a material of limited combustibility and, both surfaces of the insulating layer, have a surface spread of flame of at least plus zero or one national class or class CS3D2 or better European class see appendix A. And make contact with the inner and outer skins of cladding see figure 33.
- F - below a floor next to the ground or oversight concrete if the cavity is less than 1000mm in height or if the cavity is not normally accessible by persons unless there are openings in the floor such that it is possible for combustibles to accumulate in the cavity. In which case, cavity barriers should be provided and, access should be provided to the cavity for cleaning.
Provisions for External Surface or Walls
BB100 also states the provisions for external surfaces or walls with regard to building height and boundaries. If combustible cladding is used at ground level this should only be used as part of a fire engineering solution. This table relates to the external cladding finish only.
Compliance with Guidance
BB100 is limited in scope to schools with the highest habitable story below 18 metres in height, for guidance on schools with a story above 18 metres approved document B2 should be used. As schools are not classified as a relevant building under regulation 7 4 there are two approaches that can be undertaken:
Guidance is prescriptive and materials must meet particular reaction to fire classifications in order to be used, this means products are tested in isolation with no understanding of how they interact.
Performance based approach
Considers the external world system as a whole by large scale tests to BS8414 at which are assessed against the BR135 performance criteria. Reaction to fire testing evaluates the construction materials contribution to fire, predominantly in the early stages of a fire starting.
This video shows a sample of a range of phenolic insulation being subjected to a blow torch flame. In a nutshell the video shows that this phenolic insulation chars when it is burnt. The demonstration consists of around 8 minutes of exposing the insulation board to a blow torch flame. The heat from the flame causes the insulation to undergo pyrolysis, this pyrolysis results in the black char that is formed on the surface of the board. This pyrolysis also releases combustible gases which cannot be seen but the result of their subsequent combustion can in the additional flames that occur. These additional flames are most obvious in the first 30 seconds after the blow torch flame is introduced whilst the initial char is formed. After this the flames die down a little and the amount of char gradually increases.
After 8 minutes the blow torch is removed, and you can see that the board itself does not propagate flaming across its surface without the blow torch flame and that the board self-extinguishes. So, what is happening to the phenolic insulation to give this outcome. Firstly, pyrolysis is the process of thermal decomposition of a combustible material. It happens when the material which in this case is a sample of phenolic insulation is subjected to heat energy. In this instance the pyrolysis results in 2 products hot combustible gases, hydrolysis gases and char.
Pyrolysis is an endothermic reaction meaning it absorbs heat. The additional flames you could see during the video over and above the blow torch flame are a result of the exothermic reaction, combustion between the hot combustible gases and oxygen. The additional flaming dies down after the first 30 seconds of the video because of the char formation. This char protects the uncharted insulation beneath it from the blow torch flame and the heat from the combustion of pyrolysis gases and thus retarts its pyrolysis. Whilst the surface of the char keeps on pyrolyzing, the rate of emission of pyrolysis gases lessens and the nature of the pyrolysis gases changes. The more pyrolyised the char becomes the net effect is that rate of production of pyrolyzed gasses and the intensity of the flaming produced by their combustion reduces after the formation of the initial char layer until equilibrium is attained.
The energy released from combustion of the pyrolysis gases provide some of the energy needed to cause further pyrolysis. However, when the blow torch flame is taken away the energy from the combustion of pyrolysis gases alone is insufficient to support further pyrolysis and the insulation itself extinguishes. This shows that materials classed as combustible will not necessarily burn or combust in all eventualities. So, combustible does not automatically mean flammable. Flammability is scenario specific whereas for cluster building plans and intrinsic material property based solely on the calorific content of a material.
Case Study: National COllege for High Speed Rail
Opened in September 2017 the National College for high speed rail contains a variety of practical and classroom based learning spaces inside of visually striking yet simple building shell. To insulate the cantilevered upper floor of the main entrance providing a sheltered social space underneath, a phenolic insulation for a concrete soffit with a Lambda value of 0.018 watts per square metre kelvin was used.
The boards have been fixed directly to the concrete soffit's using thermally broken fasteners, making installation quick and simple. This commitment to creating a truly contemporary facility also include ensuring the building was as energy efficient as possible and in line with funding guidance from BIS in the skills Funding Agency of BREEAM rating of excellent has been targeted for the new development.
By using a premium performance insulation board. Comprising an advanced fibre free rigid thermoset phenolic insulation core with a thermal conductivity of 0.018 watts per meter Kelvin across all board thickness is helped to contribute towards the award of credits within the BREEAM assessment.
Case Study: Filton Avenue Primary School
Recent increases in the school's intake meant that the existing lunch facilities located away from the main buildings needed to be upgraded. Studio line proposed a simple pitched roof design using brightly coloured cladding to encourage students to enjoy healthy school meals inside. The construction work was completed by Jones building group during term time. The structural insulated panels sips that were used comprise a high performance insulation core sandwiched between two layers of OSB3. They were designed and factory cut to the project’s unique specifications by delivery partners sip build UK this off site construction process minimised site waste and allowed the panels to be quickly erected.
Once a breather membrane was applied to the outer face of the panels, the structure was watertight allowing internal trades to begin work. Under the Bristol core strategy, it was also essential that the building achieved a high level of energy efficiency. The sips system supported a fabric first construction approach limiting the heating demand of the building. The insulated core of the structural insulated panel allowed U-values of 0.17 watts per square metre Kelvin to be reached, on the wall and roof whilst its OSB3 facing and unique jointing system minimised air leakage through the building envelope. The lightweight design and excellent spanning capability of the panels also allowed the size and weight of the roofs supports to be significantly reduced compared with alternative fabric options. This made the building more cost effective to construct and allowed acoustic plenums to be formed over the dinning hall to minimised noise.
Case Study: Joseph Leckie Academy
The original 1930 school building has been replaced with a purpose build 725 square metre structure designed by Seymour Harris architecture. The new building has been constructed by contractor Speller Metcalfe and offers space for modern classrooms, special education, reprographics and administration facilities. To ensure the new building achieved a high level of thermal performance, a vacuum insulation panel VIP, for use behind a rain screen cladding system with a Lambda value of 0.007 watts per meter Kelvin was installed by subcontractors Sky green limited, helping to create a warmer more comfortable learning environment.
Building materials were carefully selected to meet both the design requirements and to ensure they are efficient for the building’s life cycle. The school was also designed to target an air permeability value of 5 cubic metres per hour per square metre at 50 pascals and a B rated EPC.
139 square metres of the VIP rain screen cladding system was specified for insulation behind the cladding system within the perforated aluminium feature window pod locations as, it can achieve an age thermal conductivity of 0.007 watts per meter kelvin which is 5 times better than other commonly used insulation materials.
This was installed alongside 675 square meters of a phenolic insulation rain screen board in a 120mm thickness to the main wall elevations offering thermal conductivities as low as 0.020 watts per meter kelvin. This optimum thermal performance was essential to achieve excellent air tightness to reach the schools targets for energy efficiency. It was essential that the build programme was planned effectively to prevent any problems with access to the site, especially during school hours when it was likely to be busy. The entire build was carefully phased to allow the school to continue as normal despite ongoing works.
Summary Part 2
That concludes Part 2 this CPD video in which we've covered:
- Daylighting and the impacts on health will being in performance
- Insulation solutions to meet the thermal comfort and daylighting requirements within an educational building
- The requirements of building bulletin BB100, designed for fire safety in schools
- Case studies showing practical examples how effective use of insulation can be achieved in various learning environments.
Thanks for watching Part 2 and if you would like further information details of any of the references made in this video, you can get in touch with us via any of the contact methods on screen now.