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SAP 2009 & Part L 2010
The UK Government's Standard Assessment Procedure (SAP) for Energy Rating of Dwellings is used as part of the national methodology for calculation of the energy performance of buildings. It is used to demonstrate compliance with Building Regulations for dwellings - Part L (England and Wales), Section 6 (Scotland) and Part F (Northern Ireland) and also provides energy ratings for dwellings. The version currently in use is known as SAP 2005. A public consultation is being undertaken on proposed changes to SAP 2009, which is anticipated to come into operation in 2010. Building Regulation changes re Energy Conservation are also planned for 2010 and hence reference is made to these where the general picture has already been indicated. Public consultations are expected in due course. The 10 main changes in SAP 2009 likely to impact design & construction are highlighted noting the role of SupaWall®. 1. Carbon emission factors: This is a big change and will have widespread implications especially to drive clients towards a more energy efficient building thermal envelope, for instance SupaWall®. Although the numbers may change slightly during consultation, the trend is clear:
This is part of a concerted policy to reduce dependence on electricity (see also item 10) and therefore electric space heating and low efficiency heat pumps will be severely disadvantaged compared to the present. 2. Thermal bridges: SupaWall® has negligible thermal bridging and is already at PassivHaus standards. SAP 2009 is just a step towards PassivHaus. Although y-values will effectively not be used and the thermal bridges will need to be added up separately, that is just a bit more calculation work. Using old terminology for now, SupaWall has a y-value of 0.04 W/m2K and hence nearly 4 times better than the worst case value quoted in SAP 2009 of 0.15 W/m2K. An opportunity for SupaWall and long overdue in Regulation. 3. Thermal mass: research work has demonstrated the similarity of thermal mass of modern timber frame, modern steel frame and modern masonry (using the normal aerated concrete blocks), the main contribution being from the plasterboard. This supports the Irish experience that found SAP differences of only around 1% between lightweight & heavyweight constructions. The largest building research centre in the world at Oak Ridge National Laboratory in the USA has also found that it is critical that the thermal mass is directly in contact with the living air spaces - even the use of dabs substantially reduces the effect. SupaWall® will have a similar if not slightly better performance than the other modern methods. Initial discussions with DuPont has highlighted that fitting their EnerGain product immediately behind the plasterboard in SupaWall® selectively in south facing rooms could be a quick win if this becomes an issue. 4. Party walls: Heat loss through party walls has recently been highlighted and this is straightforward for timber frame as simple thermal solutions are available. 5. Cooling & air-conditioning: Our experience with SupaWall® in Saudi Arabia indicates that combined with suitable ventilation and good (preferably automatic) solar shading of south facing windows, the insulation properties of SupaWall® reduces the risk of overheating. We already have good experience with SupaWall® when using the assessment of the risk of overheating in SAP 2005 and hence this is unlikely to be significant. The effect of regional climate differences is more significant and so this aspect is more of a "work in progress" for this issue of SAP. 6. Hot water: Reduced water usage is readily controlled by use of appropriate fittings. 7. Heat pumps: A new database will allow new equipment with better coefficients of performance to be included as they become available. This is a minor factor compared to the 40% increase in CO2 emissions per unit of electricity that will severely disadvantage the less efficient types and close a Regulation loop-hole. 8. Multiple heating or ventilation systems: The option to use more than one system could be of value in large complex schemes. 9. Innovative technologies: Enabling more than one new technology to be added to SAP via Appendix Q is sensible as new ideas become available. However there have been relatively few new technologies since SAP 2005 was issued. 10. Lights, appliances and cooking: a reduced level of assumed incidental gains for Building Regulations compliance. This is logical as there will be a number of drivers including European and UK regulation for the increased use of low energy lighting and appliances. Not a major issue for the applications of SupaWall®.
Summary The changes in SAP need to be considered in conjunction with the likely change in Building Regulations. The indications for England & Wales are that Part L 2010 will require an overall 25% reduction in CO2 emissions compared to the current requirements and the equivalent reduction in Section 6 for Scotland will be around 30%. Northern Ireland has historically mirrored England & Wales. Whilst this is all subject to consultation, such reductions are likely to be implemented as buildings provide an easier political route to compliance with Climate Control legislation than say a severe tax on aircraft flights for overseas holidays. Combining both the Building Regulation and SAP aspects the following is evident:
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