Integrated calculations of thermal behaviour of buildings and processes in AHU - the tool for assessment of energy performance of complex buildings

The paper presents the concept of integrated calculations of both thermal behaviour of buildings  and processes of air treatment that take place in air handling units – AHU. The model of thermal  behaviour of building is based on simplified hourly method described in EN ISO 13790:2007. Standard  EN 15241:2007 was the basis for submodels describing higrothermal processes in ventilation and  air-conditioning systems. Integration resulted in conversion of 5R1C schema to 6R1C and further in  introduction of optional equations for different types of HVAC systems. Presented method is both:  simply enough to be implemented to spread sheets (eg. Excel) and accurate enough for assessment of  annual energy use in real complex buildings. The example of simulation for an office building  confirmed that type of HVAC system (mechanical exhaust ventilation, water-air air conditioning   system and all-air constant air volume CAV air conditioning system) has essential influence on  energy consumption as in some cases energy use in AHU may be much higher than energy loads  themselves.