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

• Published in: Energy (Oxford) 2017-09, Vol.135, p.685-697
• Main Authors: Thalfeldt, Martin, Pikas, Ergo, Kurnitski, Jarek, Voll, Hendrik
• Format: Article
• Language: English
• Subjects: Automatic control; Blinds; Construction; Construction costs; Control theory; Cost analysis; Cost-effectiveness; Design standards; Energy; Energy consumption; Energy costs; Energy efficiency; Energy simulations; Façade design; Glazing; Insulation; Mathematical models; Mineral wool; Model accuracy; Net present value; Office buildings; Windows
• ISSN: 0360-5442; 1873-6785
• DOI: 10.1016/j.energy.2017.06.160

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. •Window models did not affect cost-optimal solutions despite differences in energy use.•Triple windows with WWR 25–40% were cost optimal in South, East and West facades.•North facade tolerated larger triple windows with WWR 40–60%.•The economic situation and construction cost influenced cost-optimal solutions most.•Lowest energy use was achieved with quadruple glazing and automated external blinds.