Predicting energy consumption and savings in the housing stock

There is a clear gap between actual and theoretical consumption in Dutch dwellings. Low performing dwellings tend to have a theoretical consumption much higher than actual, while high performing dwellings feature the opposite trend. These discrepancies are understandable at the level of individual dwellings and arise due to the standardizations made when calculating the theoretical consumption, however, on the level of the dwelling stock such a discrepancy is misleading and can lead to inaccurate policy reduction targets and sends wrong signals to several stakeholders (local governments, construction industry, renters and buyers etc.).

Regarding the causes of the discrepancies, they can party be explained by the features of the dwelling itself, meaning that the calculation model does not represent the reality accurately. However, a part of the discrepancy originates in the behaviour of the users and this part is difficult to quantify statistically. The results seem to indicate that underprediction is more difficult to explain and therefore probably more dependent on occupant practices than on the accuracy of the standardisation model. Overpredictions on the other hand, seem to have a lot in common with the fact that installation systems and the dwelling itself perform differently than expected. A methodological improvement seems to be more appropriate for the overpredicted cases while at the same time tackling the fact that occupants of these dwellings are likely to feel cold. For underpredictions on the other hand, changes to the methodology would mean accepting that a higher heating intensity is inevitable in efficient dwellings. While this should be further researched in the future, behaviour incentives that would encourage people to use their homes more wisely and not waste energy could be more successful.

The label calculation is easy to use and can be, as shown in the thesis, a very valuable tool for following the energy efficiency of the dwelling stock. Since the accuracy of theoretical gas and electricity calculations can easily be improved, it is a pity to miss the opportunity to do so. Several recommendations for further research and policy development were proposed regarding the methodology for the calculation of theoretical consumption. Examples of this are a revision of several standardised factors, revision of method for determining the insulation values on-site and introduction of correction factors based on actual consumption statistics. Moreover, labels that are issued should be accurate and reliable, meaning that more attention should be paid to the quality of inspections and the robustness of the software used for label calculation.

This thesis demonstrated that research on the relationship between policy instruments and their effects is crucial to ensure the effectiveness and a continuous improvement of these tools. Theoretical models, such as energy labelling, are often used to support policy decisions. As was shown, such models do not always provide results that correspond to reality, and in the case of dwellings a big reason for this is disregarding the user, who seems to adapt to the thermal quality of the house itself. However, as was demonstrated, there is a clear need for a more accurate estimation of consumption on a broader, dwelling stock level in order to enhance the effectiveness of the current renovation policies. moreover, showed that a better estimation is feasible. The thesis showed that using the current knowledge and data availability, there is few reason not to reduce the performance gap and predict the dwelling consumption more accurately.