A model for developing retrofitting strategies for office buildings

A considerable amount of material, water, energy and other natural resources are invested in the building sector. The poor performance in energy efficiency of most existing buildings and the relatively low rate of new and more efficient construction means that it will be a long time before new buildings with better performance can replace existing poor building stock. Compared to demolition and construction of new buildings, retrofitting of existing buildings may be a faster method to modernise the existing stock and mitigate unfavourable impacts on the natural environment from the building sector. However, most existing sustainability assessment methods and decision-making frameworks focus on the environmental and economic performance of buildings without much consideration of the social dimension. While retrofitting may be the best chance for existing buildings to achieve sustainability, it is necessary to consider all three sustainability dimensions when retrofitting existing buildings to achieve economic growth, protect the natural environment, and increase social wellbeing.This study develops a model for deciding retrofitting strategies for office buildings to improve their sustainability performance. Different with most other existing decision-making models for retrofitting strategies which only consider the environmental and economic dimensions, the model developed in this study integrates all the environmental, economic and social dimensions into the decision-making process of retrofitting strategies. The retrofitting strategies developed by the model can maximise improvement of existing buildings in these three dimensions within project constraints and meet retrofitting goals at the same time. This is realised via a process from conceptualisation to operationalisation. First, a conceptual model for deciding retrofitting strategies for office buildings from a triple-bottom line perspective is developed based on literature review. Then, the conceptual model is converted to an operating model to suit local situations for sustainable retrofitting. A survey and focus group discussions are conducted to collect opinions about locally suitable retrofitting activities and assessment criteria from professionals in the construction and property management sectors as well as the key stakeholders of retrofitting. Finally, a case study is conducted in which the operating model is used to develop retrofitting strategies for the case building. With suitable potential retrofitting strategies developed for the case building, the validity of the conceptual model is verified. Meanwhile, the case study illustrates the process of quantifying and using the conceptual model to develop retrofitting strategies for an office building.