New white paper on ‘Climate-conscious building’
How do we have to build today so that buildings can cope with the climate of the future? The new white paper "Climate-friendly building" from ewz shows what to look out for in planning and what a renewable energy supply can look like.
Climate change is causing summer temperatures to rise in Switzerland. This is particularly apparent in densely built cities with extensive sealed surfaces. Buildings and their surroundings must be designed to offer a comfortable quality of life in the climate of the future. ewz’s new white paper on ‘Climate-conscious building’ offers an overview of this topic. The publication serves as a knowledge base and inspiration for construction in the context of climate change and is free to download here.
Focus on cities
Green spaces with shady trees and cold air corridors intended to bring cooling are often either entirely absent or inadequate, meaning heat islands form in urban areas – where temperatures can be up to ten degrees higher at night than in surrounding areas. A catalogue of measures tailored to each specific location is needed to counteract this heat island effect. Important principles for eco-friendly urban planning and building include building position and sizing, green areas, facades and roofs, and shading.
Moderate window proportions
It’s not just exterior spaces that need to be planned and built in a climate-conscious way, but also the buildings themselves. To keep interiors as cool as possible when external temperatures rise, parameters such as building orientation, window surface areas and the building’s retention capacity are critical, starting at the design stage. Solid ceilings and floors, for example, store heat due to their mass and the room temperature rises more slowly. Windows also need special attention. Large-scale glazing is beneficial in that it lets abundant natural daylight into the interior and keeps solar heat input high in winter. In summer, however, this heat is undesirable. It is therefore recommended to avoid floor-to-ceiling windows as far as possible, and to strike a balance between aesthetics and comfortable temperatures. A window proportion of up to 30 per cent in residential buildings and up to 40 per cent in office buildings is a benchmark.
Ventilation and cooling
During long periods of hot weather, even a well-planned building heats up. It is extremely effective to dissipate the accumulated heat at night. This can be achieved by cross-ventilation, for example. Even better is to design a building that develops a chimney effect. Ventilation flaps in the façade – adjacent to the windows, for example – allow cool outside air to enter the interior and then discharge through an opening in the roof by way of the stairwell. Solutions like this entail no or minimal additional costs and work more efficiently than air conditioning units.
Unlike residential buildings, today’s office buildings are often equipped with cooling systems. This is due to the high internal loads produced by users and IT infrastructure, not to mention the high proportion of glass in the façades. There are office buildings whose requirements for cooling and heating energy are now already identical. By 2100, office buildings could require up to ten times more energy for cooling than for heating, depending on climatic developments. This would presumably increase operating costs significantly and make it more difficult to operate buildings economically.
An array of local energy sources
Environmentally friendly passive cooling is ideal for meeting the basic cooling requirements of office and residential properties. Known as free cooling, there are various energy sources in Switzerland that are suitable for this.
Geothermal heat accessed via probes is often used. In winter, thermal energy from the ground is used as a heat source, while in summer it serves also for cooling, because required temperatures are significantly below room temperatures. Lake water is another particularly suitable energy source, as the many Swiss lakes provide a valuable thermal storage mass. Because their shores are often densely populated, the lake water can be efficiently used to supply numerous buildings.
Whether it comes from geothermal probes, lake water or other sources, it is crucial that cooling uses as little energy as possible. So it’s a good idea for building owners, investors and architectural specialists to discuss this issue with an energy service provider such as ewz as early as possible and see which options are feasible. This enables the construction of buildings that can offer high comfort levels even in the hot summers of the future, without placing an additional burden on the environment.
Environmentally friendly heating remains important
It is important to bear in mind that the cooling energy needed for residential buildings is relatively low compared to the heating required. Decarbonisation of heat supply must therefore remain a priority in order to achieve net zero. Sustainable heating is not a problem nowadays, with various technically mature and economically attractive renewable heating systems available.
The ‘Climate-conscious building’ white paper provides in-depth information, detailed insights and a range of best-practice examples highlighting specific solutions for tackling this issue. The new white paper is free to download for all interested parties.