Seeing buildings as complex energy systems and as the largest collectors of solar energy

Buildings are the modern world's main and most widespread technological systems, and the most direct expression of a people's culture of life and work. Most of the energy we use – around 40% of primary energy in Europe – goes into heating, cooling and lighting building interiors and into running a growing number of devices used in buildings. Designing, building and managing energy-efficient buildings with low environmental impact is an ongoing challenge.

Over the past few decades, building roofs and walls have been continually transformed by the incorporation of new energy-related elements such as insulating materials to high-performance windows, special glass, solar-powered heating and electricity-generation systems, and low-consumption light bulbs.

Architects are switching to the "whole building" approach, which sees the various problems and solutions as a whole and tackles them in an integrated and intelligent way right from the start of the design process, when every choice is decisive.

The challenge is to move beyond the simple concept of "energy saving" or "solar energy" and aim at a combination of these and optimal building management. The basic idea is to create better buildings by putting together a strongly interdisciplinary team capable of analysing and evaluating the different aspects involved in the building's life cycle, and striking a good balance among the proposed solutions. The factors involved include the building's site and position, and the use of active and passive solar systems.

The project must take account of waste management, maintenance, the choice and reuse of materials and products, optimisation of the technological installations, the financial aspects, the landscape and the environment, combining them all in an integrated whole

The design process should dictate the choice of technologies, not the other way around, as often happens today, when available technologies and products guide the design process.

In recent years, the International Energy Agency's programmes on "Advanced Low-Energy Solar Buildings" have sponsored a number of products aimed primarily at energy saving and energy efficiency, but also at the introduction of solar technologies to meet the remainder of a building's energy requirements. These experiences have proved that it is possible to construct buildings that use on average only 44 kWh/m² per year, compared with 172 kWh/m² in other contemporary buildings. The lowest consumption obtained so far, 15 kWh/m², was in a home built in Berlin.

According to new building codes proposed in some northern European countries for future buildings, the amount of energy needed for winter heating can be reduced to practically zero with technologies that are already available (insulation, special glass, heat recovery, passive solar design and energy storage), and the remainder can be covered with active solar devices incorporated in the building's skin – devices that are not necessarily invisible, but are aesthetically designed for these buildings of the future.

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