Projects using English Regulations

What is written here applies only to projects using English 2021 Regulations.

You should read the NCM modelling guide for England and be familiar with it.

For England, there are 14 weather data files available to choose from. Select a file based on the distance to the site of the proposed building. Refer to paragraph 199 of the NCM modelling guide (2021) for more information.

Notional PV area

For full details, see sections 81-84 of the National Calculation Methodology (NCM) modelling guide (for buildings other than dwellings in England).

The area of PV in the Notional building is proportional to the building foundation area (defined in section 82 of the NCM modelling guide). It is therefore very important to ensure that the correct foundation area is entered into the studio as, e.g., incorrectly leaving the number of storeys as 1 will have a large impact on the Notional building’s performance.

Note that as the Notional PV area is proportional to building foundation area, not roof area, it is possible for the Notional PV area to exceed the building roof area.

PV area is also proportional to the heat DEMAND which is met by HEAT PUMPS in the ACTUAL building. Note that the relevant result is DEMAND, not consumption, or floor area served, or CO2 emissions, or primary energy, etc. Any heat source which has the “heat pump” checkbox ticked in the studio is counted as a heat pump, and all other sources are not counted as heat pumps; therefore ensure that heat sources are marked correctly. Note that this is not just for heating-only heat pumps; VRFs and other systems where heat pumps provide both heating and cooling should be marked as heat pumps.

A building whose heating demand is entirely met by heat pumps will have no PV in the Notional. All other buildings, including ones partially served by heat pump heating, will have some PV in the Notional building.