Low energy building retrofit: A review of objectives and solutions

Worldwide, the building sector is accountable for one-third of final energy consumption. This is expected to increase in the future. It is due to the continuing growth in demand for new buildings and the poor energy efficiency of the existing building stock. In developed countries, the ratio of new to old buildings is around 1% per year. According to the European Energy Performance of Buildings Directive Recast (Directive 2010/31/EU), optimal solutions towards low and near-Zero Energy Building (near ZEB) retrofit is of critical importance in order to achieve European Union (EU) climate and energy objectives. This has led to a large number of projects on deep building retrofit during the last 20 years. Each project has specific objective functions, depending on the adopted stakeholder’s perspective and the selected retrofit strategies are dictated by the objective functions set. This study investigates stakeholders (legislators, investors, owners and users), objectives and optimal retrofit strategies and their interrelationships. The focus is on residential buildings due to the significant opportunity for reducing their Greenhouse Gas (GHG) emissions. A matrix has been developed to classify information in order to facilitate comparison and apparent correlations to be identified. The expected outcome is the better understanding of stakeholders’ perspectives on financial, energy, GHG emissions, thermal comfort and the resulted optimal strategies