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There are about 1.7 million residential buildings in Switzerland. Experts estimate that around one million single-family houses, apartment buildings and terraced houses are insufficiently insulated and lose a lot of heat through their façades, windows or roofs. Currently, two-thirds of the energy consumption of an average private household is for space heating. According to an estimate by Gebäudehülle Schweiz, the association of Swiss building envelope companies, the energy consumption of old buildings could be reduced by up to two thirds with a comprehensive energy renovation.
Most energy for heating, hot water and electricity is lost through the building envelope. This is especially true for buildings constructed before 1975. Most heat escapes through the exterior walls, the roof or attic and the windows. Energy-efficient renovation therefore not only has economic or ecological advantages:
You can have the energy efficiency of buildings checked by independent and certified experts with the cantonal building energy certificate. With the more detailed GEAK Plus, you receive up to three individual proposals with concrete efficiency-improving measures, instructions for their implementation in stages and a prioritisation of all measures tailored to your situation, from the minimum package of measures to modernisation according to the Minergie-P standard. The GEAK Plus costs about 2,000 Swiss francs for a single-family house or small apartment building. Most cantons contribute to the costs of the GEAK Plus (to the overview), the canton of Zurich, for example, with 800 francs for single-family houses and apartment buildings.
With the energy calculator from Houzy, you can check the energy efficiency of your home free of charge and simulate the influence of individual or several energy measures. In addition, the new energy calculator calculates the investment costs, subsidies and long-term savings potential.
A lot of heat and thus a lot of energy is lost through the house façade. Especially in older houses. That is why thermal insulation is the most effective single measure to increase energy efficiency. It makes sense to have 20 centimetres of insulation and to avoid so-called thermal bridges, for example at the windows. Thermal bridges are interruptions in the thermal insulation through which heat can escape.
A lot of heat is lost especially in unheated rooms in the attic and with insufficient roof or screed insulation in converted attics. It is important that moisture can escape well despite the insulation so that condensation does not form behind the insulation material and cause water damage. That is why you should regularly check the wooden construction for any decay.
Energy-efficient windows with three panes reduce the heat transfer of the gas between the panes better than before and have a higher thermal insulation value. From an energy perspective, it makes sense to have large windows on the sunny side. They have a positive energy balance because they gain more energy from the large-area solar radiation than they lose through heat loss.
By switching from an old to a new heating system, you can use renewable energies such as wood, district heating or solar power and massively reduce your CO2 emissions. Air-to-water and brine-to-water heat pumps (geothermal probes), which generate heat from ambient or geothermal heat and feed it into the heating or hot water system, are becoming increasingly popular.
With a photovoltaic system, you produce your own electricity, reduce electricity costs, are independent of electricity price fluctuations, receive subsidies and optimise your tax burden. Systems on roofs facing south produce the most electricity. But roofs facing southeast or southwest also produce enough electricity to be profitable.
Whether the investment is worthwhile depends on many factors. That is why the calculation is quite time-consuming. It is easier and faster with the solar calculator from Houzy. In two minutes you receive a well-founded analysis of the solar potential and the economic efficiency and can simulate scenarios.
The remaining heat is lost through air exchange. Older houses have leaks through which warm air escapes in winter. No building is 100 percent airtight, not even a new building. The differential pressure measurement method is used to detect leaks in the building envelope and determine the air exchange rate. The air exchange rate is important for the indoor climate, so you should ventilate the rooms regularly. With comfort ventilation, you need to ventilate less because the stale and warm air in the kitchen and bathroom is extracted and exchanged for fresh and cool outside air in the living and sleeping areas.
All energy-related renovations need an overall concept. Regardless of whether you start with a single measure and implement other measures later or whether you plan an overall renovation. For example, it makes little sense to install a modern heating system today and insulate the façade in three years' time, because a lot of heat is lost through the uninsulated or poorly insulated façade and the new heating system is oversized after the insulation. Experts suggest this order in most cases:
With the Houzy energy calculator you can determine the energy efficiency class of your house, simulate the influence of energy measures on total energy consumption, heating costs or CO2 emissions and calculate investment costs and subsidies. You can simulate individual measures or combine and simulate measures. In this way you can quickly and easily find out how, for example, façade insulation, new windows or a heat pump change the energy efficiency and how much energy and thus CO2 you can save with an energy renovation:
The energy efficiency classes are now divided from A ("very economical") to G ("wasteful"). Houses with an energy efficiency class lower than C should be energetically renovated.
The results of the energy calculator are stored in your personal and password-protected Houzy account. There you can access them at any time and simulate other energy measures. All results are presented graphically and are easy to compare. So you understand at a glance the effects of individual or combined renovation measures on energy efficiency, energy consumption and CO2 emissions. By the way, the CO2 reduction is symbolised with trees so that you can immediately see how you are protecting our environment with an energy renovation.