Low Energy Buildings

Low Energy Buildings

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Technology

Typical European buildings require as much as 250 kWh/m², and and very often more. The most common reason for this is that they were built when oil and electricity were cheap and energy savings were not a primary concern. In contrast, low-energy buildings require up to 10 times less (< 25 kWh/m²/an). Unfortunately, while public awareness of the Passivhaus, Leeds, and Minergie labels constantly increases, their applications in buildings remain rare. This is surprising since the needs and conditions are well known.

Efficient materials are widely available. Some, such as stone, bricks, wood, straw and many others derived from mineral/plant materials have been used for millennia. Others, such as foam-glass and very efficient double or triple-layer windows are just appearing. However, with the exception of the active or semi-active walls that temporarily store energy/heat presently under study, no major technology leap is either expected or required to build super-efficient buildings.

As an example, Green-Offices in Switzerland is the first administrative building incorporating the demanding requirements of the Minergie-P-Eco label. Mainly made of wood, this 1,300m² four-storey building gets 95% of its consumable energy from renewable sources. Open interior spaces, a light well, photovoltaic (PV) solar panels, heat recovery ventilation coupled to buried earth pipes (the so-called Canadian well) and window sun visors are the secrets of this successful project.

Due to the high heat-retaining capacity of such buildings, summer comfort must be precisely analyzed. This can lead to choices that may at first seem non-intuitive, including a decrease of south and west facing glazed areas to maintain comfortable summer conditions.

Future

New material and engineering techniques will certainly contribute to improved thermal performance, but the last word usually goes to the architect. Their priority must be to examine how the building will be designed to interact with its surrounding (sun, wind, shadows, etc.) The special domain of bioclimatic architecture has recovered esteem. In bioclimatic architecture, specific solutions are worked out to address climate constraints and local conditions. This makes the building unique and perfectly integrated with its environment.