Since renovation projects often take a long time to complete, older builds often do not meet the latest insulation standards and use disproportionately large amounts of heat energy for room heating. However, with a professional energy-saving renovation, any building can be as well insulated as a new build.
Inappropriate insulating measures, on the other hand, may cause structural damage. Expert consultation and planning is therefore just as important as successful project execution by an experienced company and the use of suitable building materials.
Thanks to Germany's long tradition of energy saving in residential, commercial and industrial construction, German engineers and building contractors can be counted on as reliable partners for projects both at home and abroad. German partners are involved in many such projects all over the globe at all levels, from consulting to planning and execution.
German building stock currently consumes approximately three to (in the worse cases) ten times as much energy for heating as new builds. Up to 80% of the heat energy consumed for room heating can be saved by having insulation installed by a professional contractor and through energy-efficient renovation. Energy-efficient renovation of older builds has the added benefit of increasing thermal comfort at lower room temperatures.
Conventional building materials tend to be very good heat conductors. In other words, they do little to stop heat loss through the transfer of heat from inside the building to the exterior. Technology cannot eliminate this natural flow of heat but insulation can reduce it significantly.
To increase the insulating effect of a wall construction, additional insulating layers with low heat conductivity are added to older buildings. These insulating layers are usually positioned on the "cold" side of the existing structure. In the case of external walls, this is the exterior of the building.
In this case, the insulating materials must either be naturally weatherproof or fitted with weatherproof protection.
The following are all commonly used insulating materials and some also serve as thermal insulation composite systems:
- Foamed plastic (polystyrene, polyurethane etc.)
- Mineral wool, glass wool, cellular glass
- Mineral materials, such as porous concrete, pumice stone, perlite
- Injected cavity fill made of cellulose flakes, hemp-clay mixes
- Wood fibre, wood shavings, cork
- Plant or animal fibres, such as hemp, flax, coconut, wool
- Reed plates
- Calcium silicate plates (for example, for internal insulation)
Innovative insulation systems are also possible, for example:
- Vacuum insulation
- Transparent heat insulation
It is generally recommended that the following parts of a building be insulated:
- Roof or top floor ceiling
- Exterior walls
- Basement ceiling, basement exterior (where relevant)
- Glazed surfaces
- Heating system and heat storage unit
Special regulations in Germany
The energy performance certificate introduced in Germany assesses the energy efficiency of buildings (for example, new builds and old builds that are to be rented, let or sold). Based on this rating, specific renovation measures are proposed to improve the energy efficiency of existing buildings.
The energy performance certificate is an inexpensive way for owners to obtain initial information about how to renovate their buildings. It records the most important details of the building, provides information about its current level of energy efficiency and indicates whether renovation would make sense in each case. Specific recommendations for renovation in the energy performance certificate provide a starting point for renovation planning or for a further, detailed energy consultation. In Germany, expert initial consultations are provided by, among others, energy consultants, planning offices and skilled craft companies. For many years, the Federal Ministry of Economics and Technology (BMWi) has also been promoting qualified, unaffiliated energy consulting, and has therefore played a role in the establishment of Germany's nationwide network of independent energy consultants.
For potential buyers and tenants, the energy performance certificate provides a welcome point of comparison and a decision-making tool for selecting a building or apartment based on projected energy costs. Minimum energy-efficient standards must be met when performing extensive building renovations in Germany. These standards and those for new builds are regulated by the Energy Saving Ordinance (EnEV). Over the years, German regulations governing standards for energy efficiency have become increasingly rigorous and this trend will continue for the foreseeable future. The EnEV ensures that the insulation and technologies used in new builds meet high standards and specifies prerequisites for renovation based on the latest technological developments, while simultaneously taking account of economic viability.
As a result of the provisions enshrined in the legislation and the high demand for renovations, which can only be met by degrees, a large percentage of the labour force employed in skilled crafts or in the planning/consulting sector is currently involved in energy-efficient renovations.
German specialists are also employed as consultants or skilled craft providers on a global scale. The Federal Ministry of Transport, Building and Urban Affairs (BMVBS) and its partners foster a well-structured, high-quality transfer of knowledge as part of these projects. The BMBVS and the German Energy Agency (dena) support energy-efficient construction and renovation through well directed international projects, for example, in China. Specific measures include the publication of reference books, the hosting of regional seminars and conferences, representation at trade fairs and exhibitions, and the promotion of products and services from German companies.
The close collaboration between Germany and its international partners under the auspices of the International Energy Agency (IEA), for example, in the context of the "Implementing Agreement on Energy Conservation in Buildings and Community Systems" (ECBCS), affords German science and industry greater opportunity for teamwork on a global scale.