Insulating houses is particularly worthwhile if this is done together with the renovation of the facade or roof that the owners had already planned to do anyway.

What we do is if the outside of the building is going to be renovated in any case, it certainly makes sense to improve the building’s energy performance, for example by including additional layers of insulation. Additional insulation reduces the heating losses and thus significantly enhances the level of comfort in the building. Insulating the shell of the building has the greatest impact on costs if it is combined with efficient and smart home technology (heating, ventilation, control). In many cases, it does not cost much to use renewable heat, and the climate derives an additional benefit from this.

Furthermore, measures like independent energy advice (e.g. on-the-spot advice from the Federal Office for Economic Affairs and Export Control) can furnish the owner with important information about how economic it is to renovate the building.

Depending on the state of the building, insulation measures which are carried out irrespective of other work which has already been planned, can also be very economical and pay off quickly. This includes the insulation of the cellar ceiling, the ceiling of the upper floor and the hot water pipes. And when windows are replaced, energy efficiency is an automatic additional bonus. After all, there are no windows on the German market today which offer a poor energy performance. The Energy Saving Ordinance (EnEV) requires that all new or replacement windows must meet good energy standards. People carrying out particularly energy-efficient measures (e.g. windows with triple glazing and highly thermally insulated frames or energy-efficient heating) can obtain funding via the KfW’s CO2 building renovation programme. Funding is granted only if a qualified expert on the List of Energy Efficiency Experts confirms that the energy-related planning and the execution of the measure is undertaken correctly. Furthermore, in the case of extensive renovation work, KfW funding can be granted towards assistance e.g. with monitoring the execution of the construction work.

Thermal insulation, high-quality windows, energy-efficient heating and ventilation generate numerous advantages for owners of houses and flats: when buildings are properly insulated, they save energy and money, and guarantee comfort - both in winter and in summer. Due to the higher surface temperatures, the insulation has the fortunate “side effect” of preventing the formation of damp and mould. However, it is important that, when a building is renovated, the need for ventilation is checked by an expert. Air apertures or mechanical ventilation equipment can ensure that the necessary air exchange takes place. It may also be necessary to factor in their maintenance and follow-on costs.

In any case, improving the building’s energy performance increases its value.

Improving the energy efficiency of buildings is an important element of the efforts to attain the German government’s ambitious climate targets. After all, nearly 40% of energy is consumed by buildings in Germany - for heating, hot water, ventilation, cooling and lighting. Insulating buildings helps to lower energy consumption, save heating costs, and reduce the use of finite fossil fuels.

The assumption that insulating materials do not pay off in terms of energy over their life cycle is wrong. Insulating materials can generally recoup the energy used in their manufacture and disposal via energy conservation within a very brief period - often within a year. Very few other construction elements or materials can achieve that.

The German government does not want the tenants to bear the brunt of the efforts to tackle climate change. However, the following points should be borne in mind: without a change in user patterns or improvements in energy performance, energy prices which keep rising over a long period will result in higher ancillary costs (heating bills). If a landlord undertakes modernisation work which cuts the amount of energy consumed by the building, he or she may, in line with Section 559 of the Civil Code, be entitled to raise rents. This means that the annual rent can be increased by up to 11% of the costs imposed for the use of the building. However, the following also applies: if a modernisation measure is funded via the CO2 building renovation programme, the landlord must deduct the funding received from the modernisation costs which can be passed on to the tenants. This benefits the tenants, since the factoring in of the subsidy can reduce the rental increase.

A tenant can benefit from an improved energy performance not only through greater comfort, but also through lower operating costs: thermal insulation can result - if the building is used accordingly - in lower energy consumption and lower ancillary costs for the tenant.

Under existing law, the costs of repair work which was due in any case cannot be included in the calculation of a rental increase following modernisation. The costs of modernisation must be factored out of this. Also, the funding from the CO2 building renovation programme must be deducted from the calculation of any rental increase. The decision to increase the funding taken in the National Action Plan on Energy Efficiency can have a positive impact here.

A very small one. Of 180,000 fires in dwellings each year, only very few are the result of insulated facades. In particular, polystyrene, which is currently the subject of criticism, caused fewer than five incidents - a share of just 0.003%. A much greater fire risk derives from, for example, flammable interior fittings, wooden panelling on the facade, or flammable materials located very close to buildings, such as refuse containers and wooden sheds.

Mould is not caused by insulation. It is caused by a combination of cold surfaces and high humidity.

In fact, thermal insulation actually prevents mould, because it ensures that what used to be cold surfaces are now much warmer, and thus less damp. Also, insulation generally reduces moisture in the walls, because it protects them against driving rain and allows the walls to gradually dry out.

Also, insulation does not reduce the air exchange in a building: in unrenovated buildings, the air exchange takes place not through the walls, but through (non-air-tight) windows and leaks in the shell of the building. For this reason, when replacing old, drafty windows with new, air-tight windows, it is necessary to consider how the building will be ventilated in future. It may be the case that manual ventilation via the windows is insufficient, and that there is a need for technical devices like air apertures or centralised or decentralised ventilation systems with heat recovery. For this reason, a ventilation concept should always be drawn up when old windows are replaced.

Definitely: according to calculations by the KfW, each euro of support leverages investment of between 12 and 16 euros, and thus boosts the overall economy.

No. Studies show that that there is no relationship between rising construction prices and energy efficiency rules. Far from it. the construction costs of energy-efficient components actually fell steadily between 1990 and 2014. What we do is that property owners get better thermal insulation for the same money than they did 10 or 20 years ago. The KfW funding programmes are setting standards and preparing the market for future advances in technology.

No. This is because there are different ways to insulate different buildings. In the case of buildings subject to a preservation order, for example, where insulation using prefabricated facade elements or the like is inappropriate, there is the possibility of internal insulation. Also, roofs, cellar ceilings, top floor ceilings and pipes can be insulated without altering the shell of the building. Major progress has been made on this in recent years. Also, insulation is usually installed when facade work is already scheduled to take place (see above). The question of the future facade is therefore not related to insulation work. Of course, improving the energy performance of buildings goes beyond the subject of insulation. If a building’s heating system is replaced or converted partially or wholly to renewables, this does not normally impact on the building’s appearance.

The National Action Plan on Energy Efficiency envisaged tax breaks for work to improve the energy performance of buildings. However, it has not been possible to reach agreement on this so far. The Federal Government is looking into possible alternatives which can also result in energy conservation in the building sector.