1. Electricity emission factor and primary energy factor.
The Dwelling CO2 Emission Rate (DER) and the Dwelling Primary Energy Rate (DPER) calculation will be used for the purposes of compliance with the Building Regulations. Electricity will have an emission factor of 0.136kgCo2e/kWh, which is the lowest emission factor among the fuels. However, electricity will have the highest primary energy factor, of 1.501.
2. Flow rates of baths and showers will affect the hot water demand.
The number of baths and showers in a dwelling along with their flow rates will now be entered into SAP. This information will be used to more accurately calculate the hot water energy demand.
3. Distribution Heat losses associated with the District Heat Networks (DHN) will be increased up to 50%.
Developments with DHN will experience a big drop in their SAP performance due to higher distribution heat losses. The default value of the distribution losses under SAP 2012 accounts for 5-20% of the energy consumption; while under the new SAP, assumed losses will increase by up to 50%.
4. Lighting energy consumption.
The energy consumption of lighting will be calculated based on the amount of the lighting and the lighting efficacy (Lumens/Watt). The notional building (which is used to set the target emissions rate) will assume a lighting efficacy of 80 lm/W.
5. Heat losses for Heat Interface Units (HIU) will come from a product database.
SAP 10.1 will assume HIU heat loss based on specific product data contained in the Product Characteristics Database (PCDB) - if listed; otherwise a default heat loss of 1.46 kWh/day will be assumed.
6. Excess electricity from PV panels can be stored.
The presence of battery storage will now be an option.
For the calculation of the primary energy, different factors will be applied to the electricity generated by PV panels, depending on whether the electricity will be used within the dwelling or sold back to the grid.
7. Solar thermal and space heating
SAP 10.1 will include the option to use solar thermal for space heating (and not just hot water).
8. The reference building characteristics have been updated
Currently there are 2 options under consideration, which relate to levels being consulted on for possible use in Building Regulations. The main changes are;
Option 1: the notional building will have very low U-values (e.g for windows (including frame) which will have a U-value = 0.8 W/m2K.
Option 2: the notional building will have PV panels; the number of panels will be calculated based on the floor area of the dwelling.
Option 1 and 2: the notional building will have Waste Water Heat Recovery (WWHR).
9. Thermal bridge allowance
While the proposed new Part L regulations will remove the fabric target energy efficiency (TFEE), the default value of the thermal bridges in SAP will increase from y = 0.15 W/m2K to 0.20 W/m2K. This will encourage developers to minimise heat losses through thermal bridges.
10. Thermal mass parameter (TMP)
The option of indicative thermal mass of a dwelling (low, medium, high) has been removed. Detailed calculations of the TMP will be required for all dwellings based on the properties of the proposed materials and construction build up of the individual elements including internal partitions.