Evaluation of retrofitting strategies for post-war office buildings

2018-03-19T16:36:58Z (GMT) by Ozlem Duran
The energy used in non-domestic buildings accounts for 18 % of the energy use in the UK. Within the non-domestic building stock, 11 % of office buildings have a very high influence on the energy use. Thus, the retrofit of office buildings has a significant potential for energy efficiency and greenhouse gas emissions reduction within the non-domestic building stock. However, the replacement rate of existing buildings by new-build is only around 1-3 % per annum. Post-war office buildings, (built between 1945 and 1985) represent a promising sector for retrofit and energy demand reduction. They have disproportionately high energy consumption because many were built before the building regulations addressed thermal performance. The aim of the research is to evaluate the retrofit strategies for post-war office buildings accounting for the improved energy efficiency, thermal comfort and hence, productivity, capital and the running costs. The research seeks to provide the optimal generic retrofit strategies and illustrate sophisticated methods which will be the basis for guidelines about post-war office building retrofit. For this, multiple combinations of heating and cooling retrofit measures were applied to representative models (Exemplar) of post-war office buildings using dynamic thermal simulation modelling. The retrofit strategies include; applying envelope retrofit to UK Building Regulations Part L2B and The Passivhaus Institue EnerPHit standards for heating demand reduction and winter comfort. Passive cooling interventions such as shading devices and night ventilation and active cooling intervention such as mixed-mode ventilation were applied to overcome summer overheating. All retrofit combinations were evaluated considering future climate, inner and outer city locations and different orientations. In summary, the results showed that under current weather conditions Part L2B standard retrofit with passive cooling provided the optimum solution. In 2050, however, both Part L2B retrofit naturally ventilated cases with the passive cooling measures and EnerPHit retrofit mixed-mode ventilation cases provide the requisite thermal comfort and result in a similar range of energy consumption. It was concluded that to create generic retrofit solutions which could be applied to a given typology within the building stock is possible. The methodology and the Exemplar model could be used in future projects by decision-makers and the findings and analysis of the simulations could be taken as guidance for the widespread retrofit of post-war office buildings.