Åke Blomsterberg

Low-energy office buildings using existing technology: simulations with low internal heat gains

Although low-energy and nearly zero-energy residential houses have been built in Sweden in the past decade, there are very few examples of low-energy office buildings. This paper investigates the design features affecting energy use in office buildings and suggests the optimal low-energy design from a Swedish perspective. Dynamic simulations have been carried out with IDA ICE 4 on a typical narrow office building with perimeter cell rooms. The results from the parametric study reveal that the most important design features for energy saving are demand-controlled ventilation as well as limited glazing on the façade. Further energy-saving features are efficient lighting and office equipment which strongly reduce user-related electricity and cooling energy. Together, the simulation results suggest that about 48% energy can be saved compared to a new office building built according to the Swedish building code. Thus, it is possible, using a combination of simple and well-known building technologies and configurations, to have very low energy use in new office buildings. If renewable energy sources, such as solar energy and wind power, are added, there is a potential for the annual energy production to exceed the annual energy consumption and a net zero-energy building can be reached. One aspect of the results concerns user-related electricity, which becomes a major energy post in very low-energy offices and which is rarely regulated in building codes today. This results not only in high electricity use, but also in large internal heat gains and unnecessary high cooling loads given the high latitude and cold climate.

On the Typology, Costs, Energy Performance, Environmental Quality and Operational Characteristics of Double Skin Façades in European Buildings

Abstract The project BESTFAÇADE, sponsored by the Energy Intelligent Europe programme of the European Union, and led by MCE-Anlagenbau, Austria, accumulated the state of the art of double skin façades (DSFs) in seven European countries (Austria, Belgium, France, Germany, Greece, Portugal and Sweden). Twenty-eight façades of different buildings in all partner countries of BESTFAÇADE have been analysed for the aspects, types of façade in different countries, DSFs in different climatic regions of Europe, existing simulations and measurements, thermal behaviour, indoor air quality, comfort, user acceptance, energy demand and consumptions, control strategies, integrated building technology, cost (investment, maintenance and operation), resource conservation, environmental impact, comparison to conventional glass façades (CGFs), integration of renewable energy sources into DSFs, as well as non-energy related issues, such as, acoustics, aesthetics, fire protection, moisture, corrosion, durability, maintenance and repair. Most of the buildings are office buildings, followed by schools and service buildings. Nearly all of the buildings have mechanical ventilation systems, and both heating and cooling are performed mostly by air heating/cooling systems. The types of façades are mainly multi-storey and corridor types; in Belgium juxtaposed modules are frequently used. The façade gaps are mostly naturally ventilated (except for Belgium, where the indoor air is led by mechanical ventilation via the gap to the centralized air handling unit). The shading is performed mainly with Venetian blinds located in the gap. Unfortunately data on energy demand and temperatures are infrequently measured and rarely available. The cost of DSFs is significantly higher than conventional façades.