Building Foundation Area
This is a guide to calculating the Building Foundation Area and inputting into iSBEM
The Building foundation area must now be calculated in accordance with the NCM modelling guide 2021.
The foundation area must be calculated using the methodology below and the pre-populated value of 10000 must be overwritten.
The area of the buildingβs foundation is calculated using the following equation:
Equation 10 - where: Page 24/25 NCM Modelling Guide 2021.
π¨πππππ πππππ= π¨ππππ πππππππ / π΅ππππππs
π¨ππππ πππππππ = the total floor area of all the spaces in the modelled building which are conditioned or intended to be conditioned, e.g., after fit-out, by a space heating or space cooling system (i.e., areas of permanently unconditioned spaces are excluded), and
π΅πππππππ = the total number of storeys in the entire structure that encases the modelled building, including partial storeys and storeys containing dwellings and buildings other than dwellings (whether or not they are part of the building being assessed, i.e., represented in the software model).
NOTE- You must provide evidence of the foundation calculation in your site notes.
Convention 4.10 states:
The foundation area is calculated by dividing the total conditioned floor area by the maximum number of stories in the overall structure. The conditioned floor area will be less than the total floor area if there are any unconditioned spaces.
For a stand-alone building unit, the maximum number of stories will be the total number of stories in the building.
For a building unit which is only attached by party walls (i.e. the roof area is the same as the footprint) the maximum number of stories will be the number of stories in that building unit.
For a building unit which has any amount of party floor and/or party ceiling (i.e. it overlaps with another building unit) the maximum number of stories for calculating the foundation area will be the total number of stories in the overall combined structure. (Note however that the maximum number of stories entered into SBEM remains the number in the building unit being assessed, NOT the number in the overall structure if different).Β
If the building contains any partial storeys (includes a mezzanine or floor over an inner zone such as an office in a warehouse) the space above should always be counted as an additional storey if usable floor area. If it is not usable floor area it is not counted as an additional storey.