SAP 2012 – What’s changed? (Regional climatic data / Solar)
One of the bigger changes in SAP2012 is that it will take the regional climatic data for the dwelling into account, with a knock on effect on performance of solar technologies, depending on where the house is.
SAP dictates how a dwelling will perform against the target (TER) set by the standards, so picking out the changes from SAP2009 gives us a few pointers as regards dwelling performance under the next regulations.
Calculations of space heating for fabric energy efficiency (FEE), regulation compliance (TER and DER) and for ratings (SAP rating and environmental impact rating) are still to be undertaken with UK average weather. Other calculations of space heating will now use local weather determined by postcode region. Calculations of space cooling, where applicable, for FEE, DER and ratings will also be done with the weather data for the applicable climate region.
There may be a knock on effect from regional wind speeds on air change rates, which may affec the theat losses from ventilation
Solar PV and Solar Thermal will now show different performance depending on where in the country a house is. In some areas, they will perform better than in others, depending on the level of solar irradiance in that locale.
More accuracy will also now be available – it will be possible to model the solar panels at any degree of pitch and at any orientation; Again performance may be improved (or worsened if installed in a non optimal way).
The energy demand for Solar pumps has been reduced (although I don’t think many solar hot water systems utilise solar pumps as there an issue of cost of inverters for converting electrical current).
SAP2012 now considers if there are electric showers or not when determining hot water demand (and therefore benefit of solar hot water); There is a greater benefit from solar hot water if the showers are supplied by the boiler, rather than from instantaneous electric ‘power showers’.
Overall, indications are that both solar hot water and solar PV may come out a little better than last time around, although further analysis will be necessary once SAP software has been updated to accomodate the changes.
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