PhD Thesis - Energy Systems Research Unit - University of Strathclyde

Fig. 2.30 - High efficiency electrical demand profile for the 2-household groundfloor (February)2.5 Modelling the internal heat gainsIn Section 2.1 it was explained how the thermal demand arising from the heating orcooling energy demand required for space conditioning in a building is a factor ofmultiple aspects such as climate, building characteristics, internal heat gains etc. Inthis context, the third aspect discussed in this chapter as part of modelling thedemand side is the modelling of the internal heat gains.As discussed by Hodges [55] when modelling space heating for residential units,internal heat gains must be included in the modelling procedure. Hodges explainsthat failure to do so could lead to potentially oversizing a system, as the calculationswould not be taking into consideration the effect internal heat gains have on theindoor temperature. In summer the inverse is true; internal heat gains emitted into aspace increase the internal temperature, potentially increasing the demand for spacecooling.2.5.1 Internal heat gains - An overviewInternal heat gains in residential buildings are caused by two sources; the heatemitted by the occupants and the heat emitted from the household appliances(including lighting) [11]. Generally in sizing HVAC systems for residentialhouseholds, both the internal heat gains due to occupants and those due to appliancesare modelled as lumped sensible and latent heat loads awarded for a continuous69