Compliance

The calculations used in Heat-Box are based on:

• CIBSE Guide A: Environmental design
  CIBSE Domestic heating design guide
  (climate data & design temperatures)

  

  

  

  
• BS EN 12831:2017
  (formulas & methodology)

  

  

  

  

CIBSE Guide A provides guidance and design criteria for the design of heating systems. Heat-Box uses the external design data provided in part 2 of this document. For the outside temperature used in the heat load calculations we use the cold dry bulb temperature that is exceeded 99% of the time. In the calculations, this temperature can also be adjusted for the altitude of the location.

The CIBSE Domestic heating design guide assists specifiers and designers of “wet” central heating systems. It covers both new and existing dwellings. Heat-Box uses the internal design temperatures provided in part 3 of this document. We also use the additional thermal transmittance caused by thermal bridges provided in table 3.4 of this document and the calculation method described in part 3.5.5 for the calculation of intermittent heating.

British standard BS EN 12831-1 provides the formulas and methodology for the calculation of the design heat load of buildings. BS EN 12831-1 is the first part of BS EN 12831 multi-series and discusses space heating load. The formulas provided in this standard are used in the Heat-Box room by room calculations. The domestic hot water calculation in Heat-Box uses BS EN 12831-3, part 3 of this standard, for designing hot water systems and determining the sizing of boiler vessels.

MIS 3005 identifies the practices to be taken by MCS certified installers in the design, installation and commissioning of heat pumps. This document stipulates that heat load calculations should comply with BS EN 12831 and that the external design temperatures provided in CIBSE Guide A should be used. As described above, the Heat-Box room by room calculation comply with both of these requirements.