Windows & Doors for Education Buildings - Profile 22
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Hello and welcome to this Profile 22 CPD presentation concerning the building regulations for England and Wales. The main topics that we're going to look at today are the installation or replacement of windows and doors within education buildings.
Who are Profile 22?
Profile 22 has over 30 years’ experience of the social housing new build and refurbishment marketplace. We offer a comprehensive specification information guide including all product and legislation details which is available on CD. Profile 22 offers an extensive choice of low maintenance PVC windows doors and curtain walling along with all the auxiliary's and hardware to go with these products. All our products are designed and tested to meet all the relevant industry standards and building regulations to ensure optimum quality and durability. We offer added value through our team of customer support and technical specialists available throughout the UK. We have a national network of manufacturers and installers with specific expertise in the social housing new build and refurbishment marketplace. Profile 22 is part of the Epwin group the UKs largest extruder of PVC U products with a significant presence in the trade retail new build and social housing markets.
Regulations that affect the specification of windows and doors
This CPD presentation will look at all the major building regulations for England and Wales, that will affect the specification or installation of windows and doors. We will look at document F ventilation of buildings, document B fire safety, document M access to buildings, document N glazing, document K protection from falling collision and impact and document L conservation for fuel and power. Document F means of ventilation if we're looking at designing and constructing new education buildings and schools, we cannot refer to the building regulations alone, we need to refer to the building bulletin 101 and this concerns the ventilation of school buildings. What this states is that all occupied areas in a school building should have controllable ventilation at a minimum rate of 3 litres per second per person. All teaching accommodation shall also be capable of providing ventilation at a minimum rate of 8 litres per second per person. All washrooms shall be capable of being ventilated at a rate of at least 6 air changes per hour. Adequate measures need to be taken to prevent the build-up of condensation gases or fumes in any rooms where they may be produced.
Obviously, we need to limit the concentration of carbon dioxide in all teaching and learning spaces. Building bulletin 101 states the following when measured seated head height during continuous periods of teaching the average concentration should never exceed 1500 parts per million. The maximum concentration of carbon dioxide should never exceed 5000 parts per million and at any occupied time including teaching, the occupants should be able to lower the concentration of carbon dioxide to at least 1000 parts per million.
Designing new education buildings
If we look at designing new education buildings using mainly natural ventilation which would obviously be the most economical way, we would need the following rates of ventilation. They should be a minimum of 3 litres per second per person, a minimum daily average of 5 litres per person, the capability of achieving a minimum of 8 litres per second per person at any occupied time. When fresh air is supplied to the rate of 8 litres per second per person the carbon dioxide concentration also remain below 1000 parts per million.
Let's look at a design scenario this slide shows a single sided classroom where the windows have a vertical depth of 1.6 metres. The classroom width is 7 meters, depth is 8 meters and ceiling height is 2.5 metres, the number of pupils is 30 with 2 teachers and it is in a city location. We will look at the summer temperatures, outside temperature is 24 degrees Celsius, inside temperature is 27 degrees Celsius and the wind speed is 0. We would need to provide an area of ventilation of 3.17 metres squared to ventilate that classroom adequately. This would meet the requirements of 8 litres per second per person or 5.5 air changes per hour.
From the previous slide we saw that the area of ventilation required for the classroom was 3.17 metres squared. If we design the classroom window as shown these will actually provide an area of 4.8 metres squared. In fact there is a great opportunity to increase the ventilation with more opening vents if required. We have used a combination of high and low level vents that will enable cool air to be driven in at the bottom of the windows, drive out the warm air of the top and offer good circulation. If we also introduce high performance trickle vents to the windows, we could add an additional 38 1790 millimetres squared to the overall ventilation. During the summer months from the 1st of May to the 30th of September we need to avoid overheating of the buildings. To do this we should ensure that there is no more than 120 hours when the air temperature in the classroom rises above 28 degrees. The average internal temperature should not exceed the external temperature by a difference of more than 5 degrees. The internal air temperature when the space is occupied should never exceed 32 degrees C. To show that the proposed school will not suffer from overheating two of these criteria must be met.
Avoiding overheating in buidlings
There are various things we can do to avoid overheating in buildings these include introducing more natural ventilation through windows, louvers or trickle vents. We can add mechanical ventilation either in walls all glass vents, the use of blinds, solar shading or sola louvres to the outside of the building and of course anti-sun glass. If we now look at the refurbishment of existing education buildings, the building regulations are quite clear in what they state. For example that in all cases the opening sizes or the overall purge ventilation of any room, should not have a worst level of compliance than before the commencement of work.
However as a matter of good practice Profile 22 recommended wherever possible the minimum purged ventilation rate should be a tenth of the floor area, but we should also in refurbishments look at upgrading ventilation to that of new build, for example 8 litres per second and wherever possible trying to introduce cross flow ventilation unless rooms are adequately ventilated by other means, all replacement windows should include trickle ventilation preferably with accessible controls. Where the original windows had trickle ventilators the replacement windows should also have trickle ventilators and at least of the same opening area. Where the existing windows were fitted with trickle ventilators that would have been inadequate for the size of room and the number of pupils.
We need to look at upgrading the amount of trickle ventilation. We would recommend the following levels as a minimum requirement for trickle ventilation into classrooms and offices. For floor areas up to 10 metres squared you need 2500 millimetre squared. Floor areas over 10 metres squared will require 250 millimetre squared for every square metre of the floor area but once again we should look at upgrading the overall area of ventilation to the new build requirement of 8 litres per second per pupil.
If we now look at an existing classroom which is 7 metres by 8 metres, then that would require trickle ventilation of 14,000 millimetres squared. Once again by introducing 3 high performance overhead glass trickle ventilators these could possibly achieve nearly 39,000 millimetres squared of trickle or background ventilation. If we are introducing trickle ventilators as a means of ventilation, then they need to be accessible and they need to be controllable. Trickle ventilators fitted above 1900 millimetres from the floor or 1700 millimetres from the floor, if reaching over an obstacle need to be rod or cord operated.
What is document B fire?
If we now look at document B fire and part B1 means of warning and escape, there are a few interesting points. Every year there are 1300 fires in schools attended by Fire and Rescue services. Between the years 2000 - 2004 the average cost of these school fires was £58,000,000. Fortunately most school fires are small and contained in one room. These are fires that breakout during normal hours of school between 9:00 to 5:00 where the fire alarm gets raised early and the fire is contained. Unfortunately 56% of fires are classed as non-accidental or the result of arson and the majority of these would happen outside normal school hours. Therefore it is important when specifying windows and doors to be fitted in vulnerable areas of education buildings, that they are manufactured to secure by design. This makes it very difficult for criminals to breakthrough them and this would help reduce vandalism and arson in education buildings. If we need to provide a window which could provide an escape route in the event of a fire and then the window would have to meet the following criteria. It would need a clear opening width of 450 millimetres and a clear opening height of 450 millimetres and the bottom of the window should be no more than 1100 millimetres from the floor. However, the overall openable area should be a minimum of 0.33 metres squared. This will actually make the clear opening if it was 450 millimetres wide and 750 millimetres high. In all cases we should try and ensure unobstructed access to these types of windows.
Document M access and use of buildings
The table shows the effective clear opening through either a single door or one leaf of a double door to a building. For new buildings we can see the effective clear opening ranges from 800 millimetres to 1000 millimetres. This may depend upon the width of the access route to the door and also the angle of the door to that access route. External doors to new buildings used by the general public need to be 1000 millimetres wide. For existing buildings the effective clear opening ranges from 750 to 775 millimetres. Although again if you are refurbishing doors used by the general public to existing buildings, it would be wise to upgrade them to have an opening of at least 1000 millimetres, the same as the new build requirement.
The effective clear opening of the door will be influenced by the opening angle of the door and any hardware that is fitted to it. If the door opens to 90 degrees, then any pull handles that are fitted to the door may reduce the clear opening as shown in the drawing on the left. If the door opens beyond 90 degrees than the clear opening may be measured from the door frame on the one side to the door leaf on the other side as shown in the drawing on the right.
Doors installed in high traffic areas or in areas used by the general public, need to have clear visibility zones for both reasons of security and safety. The clear visibility zone should be from 500-1500 millimetres from the floor. However as shown this may be broken up by a central mid-rail.
Doors installed in light traffic areas or doors to be used as emergency exit doors only can be manufactured from PVC U profiles. Doors installed in heavy traffic areas or used as main entrance doors should be of a commercial aluminium or hardwood type.
We can now look at building regulation part N glazing in relation to impact opening and cleaning. There are four parts of this document that we need to refer to protection against impact, manifestation of glazing, safe opening and closing of windows and safe access for cleaning of windows.
Glazing with which people are likely to come into contact while moving in or about buildings shall if broken on impact breaking away which is unlikely to cause injury, resist impact without breaking or be shielded or protected from impact. There are no limits on the application of this document we need to consider this everywhere we fit a pane of glass.
This diagram shows the minimum areas that need to be fitted with safety glass. Certainly any glass that is within 800 millimetres from the floor needs to be made safe. Any glass in doors to a height of 1500 millimetres and in the side panels next to the door with the pane width is greater than 300 millimetres, need to be fitted with the relevant safety glass.
Because of the volume of traffic in and about education buildings and the wide range of activities that are undertaken, it is usually considered that all glass within education areas is critical and therefore is made safe. Certainly areas such as halls, gymnasiums, stairwells, playgrounds and other high traffic routes, need safety glass fitted.
Safe breakage for glass is defined in BS 6206 and there are three safety glazing classifications A, B & C with A being highest. Glazing and doors and glazing adjacent doors should be a minimum of Class C unless the dimension of the pane width his greater than 900 when it then needs to be class B. Low level glazing within 800 millimetres from the floor should also be a minimum of Class C.
Generally we can state that toughened glass will obtain a Class A rating and laminated glass would obtain a Class B rating, depending upon the glass used in the Inter layer thickness. The most common type of safety glass specification for education buildings is laminated glass to the outside, which offers good safety and security in vulnerable areas and toughened glass to the inside for safety. When specifying windows for education buildings we should also refer to BS6180 barriers in and about buildings. This states that where windows either fully or hardly fall below 800 millimetres from the floor the glass and the window frame should be designed to withstand an impact. This is where there is a risk of someone falling more than 380 millimetres. To satisfy the requirements of this 6 millimetres toughened glass is sufficient for glass sizes up to 3.8 metres squared. Windows skylights and ventilators that can be opened by people in or about the building shall be constructed or equipped that they may be opened, closed or adjusted safely. If you have unobstructed access to a window the window handle height should be no more than 1900 millimetres from the floor. If there is an obstruction and the window handle height has to be slightly lower and there should be no more than 1700 millimetres from the floor.
Windows fitted at high levels can be operated by either electrical or manual remote gearing which can easily be fitted to most types of window. Where possible we need to insure when fitting windows doors and skylights or large areas of glass, that these can be safely cleaned. Where a person standing on the ground or on a permanent stable surface cannot clean glazed services safely, the requirement could be satisfied by one of the following provisions. We can provide windows that reverse which would enable the exterior glass to be cleaned safely on the inside. These products will include tilt before turn windows, top swing windows or pivot windows. We can design casement windows that would enable people to clean the outside glass by reaching through windows. The diagrams show the safe reaches that would allow this to happen, a downward reach from an open window 600 millimetres is deemed safe. The side reached through an open light to clean a pane of glass 850 millimetres is deemed safe, or if you're stretching through a window then also 850 millimetres is deemed safe for cleaning purposes. For areas of glass that could be classed as awkward or dangerous for cleaning you can always specify a self-cleaning glass. There are various products available in the marketplace today.
Building regulation part K
Building regulation part K relates to protection from falling collision and impact. Part K2 is protection from falling and part K4 is protection from collision with open windows skylights and ventilators. Any part of an opening window that falls below 800 millimetres from the floor, needs to be suitably guarded or restricted. We see no reason why that part of an opening window needs to be that low at all and therefore any part of opening windows should be above 800 millimetres from the floor. To prevent people moving in or about buildings colliding with opening windows we can do one of two things. We can install windows so that the projecting parts are kept away from the people moving about the building or we can install features that guide people away from the windows. If the window opens greater than 100 millimetres and is less than two metres from the floor, then we have two options. We can either put a barrier around the window to ensure that people are kept away, or we can change the landscape of the building to ensure the people cannot get close to the window. Of course there is always the option that we can just restrict the window opening to less than 100 millimetres.
Building regulation pass LA conservation of fuel and power
We will now look at building regulation pass LA conservation of fuel and power. If we firstly look at part L2B existing buildings other than dwellings, we can look at the requirements for windows and doors. If you are replacing windows the windows will have to have a U value of 1.8. As an alternative option for windows in buildings which are essentially domestic in character such as care homes or student accommodation, you can fit windows with an energy rating of band C. Pedestrian doors where the door has more than 50% of its internal face glazed require a U value of 1.8. High usage entrance doors need to have a minimum U value of 3.5 all other doors need a U value of 1.8.
Any curtain walling on a building will need to have a U value so at least 1.8 or we can set a limiting U value using the formula shown, where FOL is the fraction of opening lights and GF is the glazed fraction of the curtain wall. In the curtain wall examples shown we can see that we have a fraction of opening lights of 40% and a glazed fraction of 60%. We can transpose those figures into the formula, and this will set a limited U value of 1.64 Watts per metre squared K.
Parts L2A new buildings other than dwellings
If we now look at parts L2A new buildings other than dwellings, we can state the following points the designer, the architect will have complete flexibility on window design. Although in order to avoid excessive trade off and a condensation risk and area weighted average U value of 2.2 will be imposed for new buildings. There is no guidance on the minimum or maximum area windows or doors on the new building. The optimum combination of both solar gain and U values will give the best result in SAP. Driving down U values alone may lead to a worse result. Solar gain needs to be considered and we would expand upon this issue in the next couple of slides.
We can now look at two different window constructions one a triple glazed window and one a double glazed window, both constructed using Planitherm glass and argon gas filled. The triple glazed window will have a centre pain U value of 0.7 solar gain 0.6 and an overall window U value of 1. The double glazed unit will have a sense of pane U value of 1.2. A solar gain slightly higher of 0.71, with an overall window U value of 1.4. Generally what we can say is that when we drive down the U value, we also drive down solar gain. If we are making it more difficult for heat and energy to escape from the building then, we are making it more difficult for the sun's heat to enter the building. In this particular case the triple glazing would cost you somewhere in the region of £64 per metre squared, whereas the double glazed unit would only be half of that at £32 per metre squared, but in both cases if we run them through a window energy rating Calculator both will achieve an A rating.
If we now look at a window with a triple glazed construction of Planitherm 4S glass and a Krypton gas fill, this would give us a centre pane U value of 0.4, a solar gain of 0.36, with an overall window U value of 0.8. However the glass unit cost would be £128 per metre squared. We can see that by driving the U value down so low we have also limited the amount of solar gain where benefiting by and because of this if we run this configuration through a window energy rating Calculator it would only achieve a window energy rating of B. If we considered building such as office blocks and schools which are mainly used between the hours of 9:00 to 5:00, they could benefit greatly from solar gain and therefore we need to really consider the U value versus solar gain argument.
How building regulations fall in line with the window energy rating scheme
If we now look at how the building regulations fall in line with the window energy rating scheme, we can say the following points. If we were replacing windows in a school or in an education building and they would have to have a minimum U value of 1.8 equivalent to a window with an energy rating of D. The maximum you value for new build schools would be 2.2 equivalent to a window with an energy rating of E. We also of course have the possibility of improving the performance of these windows to a C B or A rated product. An A rated product would generally have a U value of just below 1.4.
Price of increasing performance specification of windows
We can now look at the cost implications of increasing the performance specification of the window from a D rated product up to a C, B or an A rated window. The table shows the price in metres squared for the glass unit or the overall cost of a school based on replacing 200 metres squared of glass. If we're replacing windows in a school, we know that we have to fit a window with a U value of 1.8, a D rated product and therefore there are no additional costs over and above replacing the windows. If you wanted to step up to a C rated product then this would be an additional £2.31 per metre squared or an overall cost of £462. When upgrading to a B rated product the additional cost would be £8.86 per metre squared or £1772 for the overall school. To improve from a D to an A rated product, the additional costs would be an extra 15.39 per metre squared or £30.78 based on 200 metres squared of glass.
Potential cost savings of increasing the performance of windows
In the previous slide we looked at the additional costs of increasing the performance of windows, in this slide we can look at the potential cost savings.
This table is based on a primary school in Stafford where the heating costs each year were £5,507 approximately 33% of the heat loss went through their windows with an estimated cost of £1,835.
If you were to replace the windows with a D rated product you would save approximately £1,395 per year.
If you fitted C rated products you would save £1,541 a year. If you were to fit windows with an energy rating of B you would save £1,688 a year.
And finally if you were to fit a window of an energy rating of A you would save the full £1,835 a year, or however much heat was being lost through the windows because an A rated product has a window energy rating which is greater than zero.
In other words it loses no heat over a one year cycle and will add positively to the environment in which it is fitted. Having looked at the additional cost for the windows and the cost savings for the school we can now look at a payback period in months for the additional costs and the overall cost savings to the school over a 15 year period. We know that if we were fitting D rated products there were no additional costs, this gave a minimum level of performance and therefore there is no payback period for additional costs although over a 15 year period these windows would save an additional £20,925 for the school.
The additional costs to step up to a C rated product of £462. These additional costs could be paid back in as little as four months and over a 15 year period, the school would save £23,115, the additional cost to step up to a B rated products of £1,772. This could be paid back in 13 months and over a lifetime of the windows could save £25,320.
The additional costs to step up to an A rated product at £3,078. This could be paid back in 20 months and over the lifetime of the windows save £27,525. Therefore we can see for an additional initial outlay of £3,000 there could be over the lifetime of the product a saving of nearly £7000.
Cost and CO2 emissions savings of increasing the performance of windows
The previous slide showed the cost savings on the heating bills for the school. We can now look at the cost savings for the environment and the CO2 emissions. If we assume that the average school loses 10 tons of CO2 every year, we can state the following. If you were to fit a D rated product you would save approximately 1,276 kilograms of CO2 every year. A C rated product would save you 1,420 kg of CO2 every year. A B rated product would save you 2,130 kg of CO2 every year and an A rated window would save you approximately 3,333 kg of CO2 a year, approximately 33%. To put that into perspective a C rated product saving 1420 kg is equivalent to 8 double Decker buses full of CO2 gas saved every year, there for an A rated product was save the annual equivalent of 16 double Decker buses full of CO2 great savings for the environment.
Introduction of RCM (recycled composite material)
There have been recent advances in window production and manufacturing which makes them more thermally efficient. This is the introduction of RCM or recycled composite material used as reinforcement bars. Traditionally PVC windows have been reinforced with either steel or aluminium sections these of course are not very thermally efficient and a very costly. The benefits of using recycled material is that we increase the thermal efficiency of the window. We are using end of life material that we are taking from the old PVC windows that were fitted 20 to 25 years ago. We are recycling that material and reusing it again in the new Windows that we produce. These sections are approved by WRAP the waste resource action programme by the government it could be seen on their website. Obviously if we expect our main profiles to have a life expectancy of 35 to 40 years, we also expect the RCM reinforcement to last this amount of time without a deterioration of product performance.
Recycling in the construction industry
The drive within the construction industry to cut waste, reduce CO2 emissions and conserve resources is gathering pace. At the top of the construction materials agenda is the issue of recycling. The PVC industry is highly regulated and provides us with the basis for some of the most thermally efficient secure and low maintenance building products available today. Increasing numbers of old PVC products and single glazed windows are now being replaced with these improved performance products. And a common misconception is that all PVC cannot be recycled. Nothing is further from the truth. PVC is fully recyclable, and decora is above forefront of recycling PVC in the UK. The company has been processing increasingly significant volumes of post-industrial PVC waste off cuts from window and door manufacturers for over a decade. We can see the off cuts being loaded into crates ready for collection and delivery to our size reduction plants. Now with major investment in infrastructure and equipment we have developed a unique dedicated post-consumer waste recycling service. We can provide specially developed green trolleys that can be loaded with old deglazed windows and PVC products ready to be made into the next generation of products.
Once the waste material has been collected it is delivered to our unique post-consumer waste facility and our recycling process begins. The frames are fade into Titan which reduces them to coarse fractions of PVC and metal the metal separation process then removes the majority of ferrous and non-ferrous fragments, which go for independent recycling. The PVC fraction can then be manually rough sorted for primary contaminants before granulation into a regular chip form. As granulous the PVC is then subjected to a further cleaning and purification operation. Firstly fine particles of PVC and debris are removed followed by a more rigorous metal separation process, which removes the vast majority of remaining metal. The next process removes non PVC materials these include other plastics as well as wood gasket materials and larger pieces of debris such as mortar and silicone.
Following this white PVC content can be extracted to retain the maximum benefit back into building products. At each stage the by-products can be used for other building related applications minimising materials once destined for landfill. The resulting granulat is now much cleaner and ready for conversion into a pre exclusion form. One option is to grind the granulat down into a powder. This is sieved to control the particle size for uniform powder density, ideal for high volume extrusion. Alternatively we have developed a pelletising process which allows the granular to be filtered as a melt, to remove the finest of contamination that may be left. The resulting palette is both clean and extrusion friendly. Additives and pigments can be added to give consistent colour and processing, allowing our recycled PVC to be converted into a finished building product. Bulk bags of finished pellets or powder are now ready for shipment to the exclusion operation. We can now see the extrusion plants making a central strengthening profile for Windows from our 100% recycled material. This window and door insert is now used in the majority of finished products instead of the traditional aluminium profile. You can also see extrusion of cavity closers that use 100% recycled materials for use in new build homes.
The strengthening profile and cavity closer have both been approved by WRAP the government industry approvals body as environmentally efficient products. In fact we have taken the production a stage further and produced a 100% recycled window, using separated white fractions which we believe is the future for all PVC building products. The start of this video saw old PVC windows being taken out of Liverton court tower block in Manchester for recycling. Here we now see our recycled windows being installed in Corris Avenue, just a stone's throw away. The replacement of the existing windows on these 14 properties with a new generation of energy efficient and low maintenance PVC U products that are manufactured from 100% postconsumer waste, has allowed Northwood’s Housing Association to close the loop on the recycling process. This project the first in the UK forms part of the housing associations commitment to minimise the environmental impact on its estate management and maintenance activity. And it's not just windows and doors the group also extrude many different products using some form of recycled content such as, these rainwater products. Throughout the whole process we offer advice on how best to recycle and how we can help you achieve your goal. You can save time and money and ensure you stay green compliant throughout by using our unique fully closed loop manufacturing of PVC products.
As you have just seen in the video, we're now producing a 100% recycled window. The important point to highlight here is that RECO 22, the 100% recycled profiles have only 6% of the carbon footprint of that compared to profiles using Virgin material. Very good savings for the environment. Due to the savings of CO2 in the production of the product and the impact on the environment if we look at the green book for specification, we can see that RECO 22 profiles have an A + rating across all the sectors retail, homes, schools, offices, health and sheds. The other important points to note about the recycling of PVC material is that it can be recycled over 10 times without deterioration in service performance. The BRE gives PVC a life cycle of 35 years and British standard BS EN 12608 gives profile life of 40 years.
For further information on the products or services that Profile 22 offer please visit our website www.profile22.com or Alternatively please contact our marketing Department at Telford telephone number 01952290910.