Thermal performance LIST OF CONTENTS

Transcription

1 LIST OF CONTENTS Page 1 A brief explanation Page 2 Heat loss through walls Page 3 Heat loss examples Page 4 Secret behind the walls. Thermal Storage Page 5 Air tightness Page 6 Density of EPS Page 7 Insulating Concrete Formwork plastic or steel ties Page 8 Payback Page 9 WARMERWALL real world evidence of exceptional performance Page 10 SAP assessment Page 11 Information sources

2 Brief explanation (updated 26/04/2017) to help specifiers, developers, builders, associated professions and self builders with what is required for part L of the Building Regulations. There are many approved methods that can be used to arrive at the U value of a wall (which meet Building Regulation requirements ). Methods include; Numerical exercise to a particular BS or other accredited and approved standard others will be by laboratory testing and others by real world testing. The graphite impregnated super insulation used to make WARMERWALLforms has a thermal conductivity value of 0.03 W/m/k (not to be confused with U value) when tested by BBA (European harmonised lambda 90:90 test protocol) in Hot box tests show that when a WARMERWALL with render or brick on the outside, a 150mm concrete core in the form and 12.5mm plasterboard on the inside the cumulative or rolling average U value is W/m²k after a 10 day settling in period. This U value takes account of the outside temperature swings which naturally occur in the real world and the influence of the high mass concrete core acting as a thermal storage thus improving the walls overall thermal performance. A numerical exercise which does not take into account the thermal storage effect would show a U value of W/m²k. To keep this difference in perspective, the difference between and presents a cost of just 6.93 per year for an average detached house (see example pg 3). The lambda 90:90 conductivity value takes in to account the consistency and aged performance of insulation and should not be confused with lambda mean which does not take age performance into account but may suggest better U values. Also consider the high thermal mass of a WARMERWALLwhich will provide a comfortable and even internal living temperature causing heating systems to cycle less often and in turn repay with lower energy bills for the life of the building. pg1

3 Heat lost through the walls. You may be surprised by how much your home costs to heat. We will explain where the heat is lost and how to get the best for your hard earned money. Every element that goes to make up the exterior envelope of your home (floors, walls, doors, windows and roof) will allow heat to leak away adding to your fuel bills. The cost of one of these elements will correlate usually to how good they are at stopping your heat from flowing through them. The golden rule is not to spend more on making each of these elements better (eg better insulation) than what they in turn would save you in energy over a given period. Some interesting facts: Using our example with a gross wall area of 151m² with energy prices at 5p per kwh the heat loss through that wall would be: Building Regs 1965 U value 1.7 w/m²k. Building Regs 1985 U value 0.6 w/m²k. Building Regs 2010 U value 0.3 w/m²k Warmerwall U value w/m²k Passive house wall U value around 0.13 w/m²k 224/year 80 /year 40/year 30/year (cumulative U value) 17/year The next few pages will give examples and guidance on some of the frequently asked questions about heating and getting the best for your money. pg2

4 o w Example breakdown of heating costs h d w d h o DETACHED HOUSE (downstairs 21degC & 2air changes/hr, upstairs 16degC & 1air change/hr) Fuel price pence per kwh 5p Width of your home 10m Depth of your home 5.7m Height of your home 4.8m Gross wall area 151 m² m² Cost/year Windows and doors m² Net wall area m² Area of ceiling (roof level) m² Area of floor (ground level) m² Volume of inside mᶟ Total fabric losses Warming the air without MVHR Warming the air with MVHR m³/floor Total heating cost with MVHR per year Total heating cost without MVHR As in common with all build methods the cost of hot water and electricity to supply appliances in the home are extra to the figures abovethese will however, contribute to reduce the heating bill further. pg3

5 SECRET BEHIND THESE WALLS BEING SO AMAZINGLY ENERGY EFFICIENT AGAINST ANY OTHER BUILDING METHODS? No secret, just pure physics and common sense. The walls have a very high thermal mass, (providing Thermal Storage), are pre-insulated, and have no joints or cavities for your heat to escape by way of drafts. Because of the extraordinary WARMERWALL Thermal Storage capacity, it is capable of balancing out exterior temperature differences that occur throughout the day thus acting similar to a thermal screen. Tests have shown that a significant change in outside temperature can be held back for more than 24hrs compared to a timber wall (2½hrs) and a brick wall (9hrs), that s a potential 21 hours that your heating would not have to come on. Consequently in the summer the wall would perform to balance out the high temperatures of the day. The job of maintaining a comfortable temperature inside is achieved, something not possible with a low mass wall with a much greater U value. Your comfort, your money. Because the core strength of the wall is provided by high density concrete there are no joins or cavities unlike brick and block or timber walls. This provides a super strong cosy warm draught free living space. The inner concrete core during the annual heating period assumes a temperature of about 16degC, like wrapping your home in a warm blanket. The benefit of thermal storage provided with high thermal mass building. pg4

6 Air tightness. U values are banded about much more than air leakage and yet most of the cost of heating can be contributed to air leakage (drafts). Typically ICF buildings have an air tightness of less than 3 m³/(h.m²) compared to SAP default of 10 m³/(h.m²) expected under the Building Regs. Testing for air tightness is different to what air changes are necessary for a heathy living environment. Healthy ventilation for living areas is 2 air changes per hour and for sleeping areas 1 air change per hour. Extreme example: Imagine if you were stood next to a freestanding wall with a U value of zero. The benefit of this super insulated wall would only come into play if you were separated from the air the other side of the wall. Please ensure that your appointed SAP assessor is aware of the standard air infiltration / leakage of WARMERWALLswhen built correctly so that the default settings in their programme is adjusted accordingly and you get a correct SAP assessment. It is very common for a WARMERWALLhouse to achieve a heating requirement of 15kw/m²/yr (passive house standard) with a standard wall which has a U value of or and with an air leakage of 3m³/(h.m²). This would be without renewables and without specialist heating systems. pg5

7 The density of the EPS (build grade expanded polystyrene) has been increased by 20% giving a still better U value and providing a very firm, rigid form giving you extra confidence in its strength for your build whilst maintaining the same dimensions. The steel ties already make for very rigid forms but the increase in EPS density to 30G/L gives a 20% improvement in the strength of the formwork against damage and possible blowouts. Compare the strength and rigidity of the WARMERWALL form against any other ICF on the market. The increase in density also gives an improved lambda value from around to providing a better overall U value, giving you cheaper energy bills. pg6

8 Insulating Concrete Formwork made with either plastic or steel ties are both excellent at outperforming other building methods -providing a comfortable home with very little energy (heat) loss. ICFs made with Integral plastic ties should be cheaperto buy than those with steel ties because plastic is normally cheaper than steel. Steel ties are less resistant to the smooth flow of concrete during a pour because they can be of a much smaller profile due to the strength of steel compared to plastic. Plastic ties can melt in the event of a fire causing whatever they are supporting to fall. Steel ties can be found easily beneath the surface of plasterboard by simple metal detector. Steel ties will support much greater weight than plastic ties and can be used to support radiators which is not advisable with plastic ties as the ties could become brittle and fail over time. Through real world hot box teststhe difference in the cumulative U value of similar ICFs with steel ties (0.227W/m²k) and those with plastic ties (0.233W/m²k) is.044w/m2k giving a numerical advantage to steel ties ties of about 80p/year in heat savings (see example house pg3). The patented strong steel fixing strips in the WARMERWALL PolySteelforms (not to be confused with plastic ties) are provided to save the need to drill into the concrete to hang cupboards, radiators, wall coverings etc. No holes = no leaks pg7

9 Payback. If you are lucky enough to have a selection of deposit accounts in which to place your money, would you go for the lowest rate of interest? No of course you wouldn t, so why would you even consider paying for something that will not give you the best return? We are often asked what is the U value of your wall?, Whatever you want it to be is the reply. However, as with almost everything there is a tipping point whereby the law of diminishing return kicks in. The examples we use in this document are based on pure fact and will provide guidance for you to decide. Did you know that a detached house built withwarmerwall which has a gross wall area of 151m² will lose only around 30/year (each kwh costing 5p) through the wall? If you improve the U value of that wall to 0.13 the extra saving will be 13/year. If the extra insulation can be bought and installed for around 2000 it will take you years to get your money back -that s if you managed to lend the money in the first place at a flat rate of 2% interest for that period of time. pg8

10 There are two semi detached houses and one detached house on one site in Cheltenham with standard WARMERWALLforms built in The tenants are delighted with the low cost of the energy bills. The houses have full height basements which extend the full footprint of each of the properties. The living space of each house is around 114m². The heating is by standard combination boiler and each house has a whole house MVHR system installed to minimise the cost of air heating. There are no renewables such as solar panels or heat pumps and the insulation in the ceilings and floors has a standard U value of 0.11 with the standard WARMERWALLforms. The doors and windows are A rated. Energy bills that have been collected over two years for the gas (heating and water) has amounted to around 250 per year for each of the houses. The tenants at first were reluctant to let us have a copy of the bills for fear that they were wrong but even after the energy company changed the metering and double checked the energy consumption they were also surprised by the vindicated results which remained about the same for the following years. pg9

11 SAP program and working out the Target Emission Rate (TER). Importantfactors to consider by your energy assessor. The building Regulations in Scotland, England or Wales provide guidance as how to achieve thermally efficient houses / premises and give examples of how the objectives could be achieved. The various elements of a build and the workmanship need to work together to produce the required results to meet what is required by the yourself and the Building Regulations. The thermal efficiency of a wall requires that air leakage is kept to a minimum and linear thermal transmittance (cold bridging), is also kept to a minimum, in order that the U value of the wall as designed can be achieved. The thermal mass of the wall can also considerably improve the overall thermal efficiency of the built wall. The SAP assessor should set the air leakage rate from 10m³/(h.m²) usually default to 3m³/(h.m²) which is what is usual and should be expected as a minimum from a house built with WARMERWALL ICFs. The cold bridging details should also be input into the SAP calculation from their default setting to those which would normally be expected from WARMERWALL, figures available on request.. pg10

12 The guidance provided within this document is based on information from respected sources. It is our interpretation of this information and results of real world testing that has been used to produce this guidance. If you believe that our interpretation is wrong or not clear enough we would be happy to discuss. It is for these reasons that we advise you to seek your own professional advice on such an important matter of energy efficiency in your home before making your final decisions. Comfort temperature in the living room of a house is shown as 21 C with 2xAirC/H. Sleeping areas 16 C. with 1xAirC/H. Average temperature during the heating period October to May is 10.4 C. taken from the last 100 years of data from the UK meteorology office. The heating hours during the heating period is taken to be 2565 hrs. 74hrs/wk(5x10 + 2x12) x 52 wksx 0.67 (eight mths Oct-May). The Insulation static and cumulative U value of the WARMERWALL (PolySteel patented design ICF) is provided from the National Physical Laboratory. The lambda 90:90 insulation value is confirmed by the BBA. MVHR unit is taken as having an energy efficiency of 90%. Volume x Air changes x Temp. dif. X Air coef. X (hrsper yr/2)/1000 x (cost per kwh/100) = Cost of space heating per year. Window and door openings of the house used as example is taken to be 15% of the gross external wall area. Review date 26/04/2017 pg11