Advanced Performance Windows - Profile 22
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Hello and welcome to this Profile 22 CPD presentation concerning advanced performance windows or perhaps a more appropriate title would be high performance thermally efficient windows.
Who are Profile 22?
Profile 22 has over thirty-year 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 ancillaries and hardware to go with these products. All our products are designed and tested to meet 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 UK’s largest extruder of PVCu products with a significant presence in the trade retail, new build and social housing markets.
Window energy ratings
Window energy ratings were first introduced into the building regulations in 2006 when document L was updated. This gave window manufacturers the opportunity to show the window energy rating label on their products, and show the level of performance. At that point all window manufacturers had to be registered with the British Federation Ratings Council who would oversee the manufacture and test evidence of these windows.
To produce a window energy rating figure, we need to look at three elements of the window. Firstly, we need to look at solar heat gain and how much positive heat can we can allow from the sun to enter into the building to warm the premises. We then need to look at the thermal losses through the window, through convection, conduction and radiation, or as we generally term it, the U-value of the window. We also need to look at the air losses through the window.
All window energy ratings are produced based on the standard model that you see on the slide; a side on window, next to a fixed 1480mm high by 1230mm wide. The actual calculation is 218.6 multiplied by the window solar factor, minus 68.5, multiplied by the combined value of the window U-value, plus air infiltration factor. What this gives you, is a comparison of different window constructions and glazing, so you can see how a window performs with a large frame or a small frame, with different glass units to see how energy efficient they are.
Window energy ratings are expressed in units of kilowatts and hours per square metre per year. From this figure the window is allocated a band from the A - G rating as shown on the scale. The interesting figure on this, is that an A rated product has an energy loss which is greater than zero, so therefore we can say that adds positively to the environment, in which it is fitted. As you move down the scale a B rated window would lose 10 kilowatts an hour per metre squared, and a C rated 20 kilowatts an hour per metre squared etcetera.
As stated previously, window energy ratings are now listed in the Building Regulations document L, and are a legitimate way to show compliance with the Building Regulations. This is all on the back of public awareness of trying to reduce global warming and reduce the CO2 emissions from buildings. So, let’s recap on what the Building Regulations state.
Part L1B – Existing Dwellings. If we were to replace windows in an existing dwelling the overall window U-value would need to be at least 1.6, or alternatively you could fit a window with an energy rating of band C. Replacement doors would need a U-value of 1.8.
Document L2B – Existing Buildings other than dwellings. If we were to replace the windows, they would have to have the U-value of at least 1.8. An alternative method for buildings that have mainly domestic in character i.e. student accommodation and care homes, we could fit windows with an energy rating of band C. High entrance usage doors would need to have a minimum u-value of 3.5. Pedestrian and other doors would need a U-value of 1.8.
If we now look at new buildings, we know that the compliance with the Building Regulations is shown by the calculated carbon dioxide emissions from the new dwelling or building. The standard Assessment Procedure or SAP is the calculation tool used to show compliance. What we can say about the Building Regulations changing in 2010, is that there has been a 25% reduction in the overall CO2 emissions compared to document L in 2006.
New dwellings and new buildings
What we can state about new dwellings and new buildings, is the designer or architect will have complete flexibility on window design. Although, in order to avoid in excessive trade off of components and a condensation risk, an area weighted average U-value of 2, will be imposed for dwellings and 2.2 for all other new buildings. There is no guidance on the minimum or maximum area of windows or doors. The optimum combination of Solar Gain in U-values will give the best results in SAP. Driving down U-values may lead to a worse result; Solar Gain needs to be considered and we will expand on this point 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 Centre Pane U-value of 0.7, Solar Gain 0.6, and an overall window U-value of 1. The double-glazed unit will have a Centre Pane U-value of 1.2, a Solar Gain slightly higher at 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 the 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 these cases, if we run them through a window energy rating calculator, both would achieve an A rating.
Windows with triple glazed construction
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 we’re 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 buildings such as office blocks and schools which are mainly used between the hours of 9-5, they could benefit greatly from Solar Gain and therefore we really need to consider the U-value versus Solar Gain argument.
Looking at how the window energy rating scheme falls into line with the Building Regulations, we can state the following. For new buildings where we would have to fit windows with U-values of 2 or 2.2, this would be equivalent of a window with an energy rating of band E. For existing non dwellings we would have to fit windows with U-values of 1.8, equivalent to a window energy rating of D. For existing dwellings, we have to fit windows with a U-value of 1.6 or have an energy rating of band C. At any point we can look at increasing the thermal efficiency of the windows and increasing to either a B or an A rated product. An A rated product would generally have a U-value of just below 1.4.
This slide illustrates the additional costs of increasing the window performance from a C to an A rated product in existing dwelling. We know that if we are replacing windows in an existing dwelling, we need to fit a window with an energy rating of C. This means there are no additional costs over and above replacing the windows. If you were to increase the windows performance to a B rated product, the approximate cost would be an additional £6.55 per metre squared, or £98.25 for a house having 15 metres squared of glass. If you were to upgrade to an A rated product, this would be an additional £13.08 per metre squared, or £196.20 for the whole house.
It is estimated that 20-25% of the heat loss of a dwelling is through the windows. Of course, this will depend greatly on the construction of the building and the amount of glass. In general terms the cost of the heat loss would be about £188 a year on fuel bills. If you were to replace old single glazed windows with C rated products, the savings on fuel bills would be somewhere in the region of £158. B rated products would save somewhere in the region of £173 a year. And of course, if we stepped up to an A rated product, which theoretically doesn’t lose any energy of a year’s cycle, savings of fuel bills would be the full £188.
Based on the figures we have previously seen; we can now look at the payback period for the additional cost of these products and the cost savings for the household over a 35-year period. If we were replacing C rated products into a house, there were no additional costs and therefore there is no payback period. However, over the lifetime of the window, it would save over £5530 on the heating bills. To step up to B rated products there was an additional £98.25. These additional costs would be paid back in as little as 7 months, and over the lifetime of the product would save £6055 on the heating bills. The additional costs of £196.20 to step up to A rated products, would be paid back in 13 months and over the lifetime of these windows, would save over £6500. Therefore, you can see that for an additional outlay of less than £200, there could be an additional £1000 saved on heating bills.
It is estimated that the average CO2 emissions from a typical domestic dwelling is 6 tonnes per year, by replacing the old-style glazed windows with C rated products, this would save 752 kilograms of CO2 every year. This is the equivalent of 5 double-decker busses full of gas. A B rated product would save 1218 kilograms of CO2 every year, the equivalent of about 8 double-decker’s full of gas. And an A rated product would save approximately 1504 kilograms of CO2 every year. This is roughly equivalent to 10 double-decker busses full of gas saved every year, great savings for the environment.
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 are 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 20/25 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 Program by the government, and can be seen on their website. Obviously, if we expect our main profiles to have a life expectancy of 35/40 years, we also expect the RCM reinforcement to last this amount of time, without a deterioration of product performance.
Cutting waste and reducing CO2
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 bases 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 Dekura is at the forefront of recycling PVC in the UK. The company has been processing increasingly significant volumes of post-industrial PVC waste offcuts from window and door manufacturers for over a decade. We can see the offcuts being loaded into crates ready for collection and delivery to our size reduction plant. 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 fed into tighten, which reduces them to core fractions of PVC and metal. The metal separation process then removes the majority of feres and non ferres fragments which go for independent recycling. The PVC fraction can then be manually rough sorted for prime re-contaminants before granulation into a regular chip form. As granulate 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.
Removing non-PCV material
The next process removes non-PVC material, these include other plastics as well as wood, gasket materials and larger pieces of debris, such as mortar and silicon. Following this, white PVC content can be extracted to retain the maximum benefit back into building products. At each stage, the byproducts can be used for other building related applications, minimising materials once destined for landfill. The resulting granulate is now much cleaner and ready for a conversion into a pre-extrusion form. One option is to grind the granulate down into a powder, this is sieved to control the particle size for uniformed powder density ideal for high volume extrusion. Alternatively, we have developed a pelletising process which allows the granulate to be filtered as a melt, to remove the finest of contamination that may be left. The resulting pellet 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 extrusion operation. We can now see the extrusion plants making a strengthening profile for windows from our 100 percent 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 percent 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 in environmentally efficient products. In fact, we have taken the production a stage further and produced a 100 percent 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 Coress 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 PVCu products, that are manufactured from 100 percent post-consumer waste, has allowed Northwoods 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 percent recycled window. The important point to highlight here is RECO 22, the 100 percent recyclable profiles have only 6 percent of the carbon footprint of those compared to profiles using virgin material, very good saving 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 plus rating across all the sectors; retail, homes, schools, offices, health and sheds.
The other important point 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 PVCu a life cycle of 35 years and British Standards BS EN 12608 gives profile a life of 40 years.
For further information on the product or services that Profile 22 offer, please visit our website – www.profile22.com or alternatively please contact our marketing department at Telford. Telephone number 01952 290910