Application of partial safety factors in building energy performance assessment

In practise many buildings show significant deviation between the predicted annual energy consumption and the actual energy consumption. One of the main reasons for the discrepancy is the difference between the assumptions made during the calculations and the actual conditions including occupants' behaviour. This paper presents two methods to consider uncertainty and spread of energy consumption calculations in practise, namely a simulation approach and a safety factor approach. A simulation approach is investigated using Monte Carlo analysis where a comprehensive list of stochastic input parameters is evaluated by sensitivity and uncertainty analysis to develop a significantly reduced set of stochastic input parameters. The safety factor approach provides a means of enforcing the maximum allowed energy consumption in the building code by multiplying the maximum limit by a partial safety factor to obtain a design energy consumption that can be used for the usual energy calculations.