Window model and 5 year price data sensitivity to cost-effective façade solutions for office buildings in Estonia

This study provides information about development of cost-effective facade solutions during the last 5 years and illustrates the importance of different variables such as accuracy of window models, construction costs, energy prices, interest rate and inflation. The cost-effective South, East and West facade solutions were triple windows with window-to-wall ratio 22-40% and external wall mineral wool insulation thickness 150-200 mm, whereas larger windows could be used in the North facade. The economic variables and construction price changes have had the largest influence on the analysis of cost-effective facade solutions. Lowest energy use was achieved with large quadruple windows and automated external venetian blinds with an advanced control algorithm. Wider market uptake of efficient window solutions could allow more architectural freedom from the point of view of energy-efficient and financially feasible facade design. Using detailed window models instead of standard windows did not influence the cost-optimal facade solutions, but had energy and load effects in both directions.