Modelling Energy Conservation and CO2 Mitigation in the European Building Stock

Doctoral thesis, 2013

This thesis investigates energy conservation in building stocks with the aim of developing a methodology that can be applied to the national building stocks of the European Union (EU). For this purpose, a bottom-up building-stock model and a methodology for describing the building-stock have been established. The model is based on a one-zone building energy balance, which provides the hourly net energy demand for all end-uses and which has been validated by empirical and comparative means for selected buildings. The results for representative buildings are subsequently extrapolated to the entire building stock with respect to net and final energy demand, associated CO2 emissions, and costs for implementing a portfolio of energy conservation measures (ECMs). The methodology for building stock aggregation through archetype buildings comprises the following elements: (1) segmentation, in which the number of archetype buildings required to represent the entire stock is decided according to building type, construction year, heating system, and climate zone; (2) characterization, whereby each archetype is described in terms of its physical and technical characteristics; (3) quantification, whereby the number of buildings in the stock represented by each archetype building is determined. The archetype description is used as an input to the model, from which the final energy use is calculated, and the results are validated by comparison with the available statistics. The archetype description has been developed and validated for the building stocks of France, Germany, Spain and UK, which account for half of the final energy use of the residential and non-residential buildings in the EU-27 countries. Using the building stock model to apply various ECMs to the Swedish residential building stock and the entire Spanish residential and non-residential building stock, which are representative of Northern and Southern EU buildings, respectively, the final energy demands of the Swedish and Spanish building stock are found to be reduced by 50%. In both countries, the different forms of envelope upgrades confer the largest technical potential reductions for all buildings. However, other ECMs with significant potentials differ between the two countries and subsectors. The levels of CO2 emissions from the Swedish residential buildings and the Spanish buildings can be reduced by 60%–70%. Although the application of the ECMs generally reduces CO2 emissions, the effects of measures that reduce electricity use for lighting and appliances rely on whether the saved electricity production is less or more CO2-intensive than the fuel mix used for space heating. Techno-economical potential reductions of energy demand by 20%–30% are identified for Sweden and Spain, corresponding to CO2 emissions reductions of 40%–50%. These potentials increase when packages of ECMs are applied. Furthermore, the packages were more cost-effective than the individual ECMs. The market potentials identified are substantially lower than the techno-economical potentials. If the techno-economic potentials identified in this work are to be implemented, there is a need for strong policy measures to influence stakeholder actions.