Systematic comparison of simplified methods to estimate the building design heat load

Abstract

The design heat load according to DIN EN 12831 is crucial for building energy systems design. German technical specification DIN/TS 12831 provides two alternative, simplified methods to calculate the design heat load: (1) based on linear regression using selected measurement points of the final energy consumption and the outdoor air temperature; (2) based on the annual final energy consumption and heating degree days. To accelerate the transformation of the building sector, usage of these simplified methods is desirable. However, the technical specification and related research contributions do not state the accuracy of these simplified approaches. Thus, in this contribution, we validate the simplified approaches using the final energy consumption from dynamic simulations against the design heat load calculated based on DIN EN 12831. Systematically varying building envelopes, air exchange rates, internal gains, domestic hot water consumptions, room temperatures, and model fidelity, we estimate the accuracy of the simplified methods. For method (1), daily final energy consumption measurements yield the highest accuracy among all scenarios: On average, the design heat load is 0.35 % off, with a standard deviation of 2.5 %. For method (2), the deviation varies between +10 % and –21 %, with an average of 6.7 % and a standard deviation of 7.7 %.