Insulating Instead of Heating – The Solution of the Future?

Author: Thorsten Rienth

Jun 07, 2023 Sustainability / Innovation

Heat pump, biomass, or sustainably produced gas? In Germany, the debate about the right type of heating for the future has been ignited. At the same time, there are innovative methods for insulating roofs and facades.

While the draft of the Buildings Energy Act (GEG) is currently going through the parliamentary process in the German Parliament and Federal Council, homeowners are pondering the right type of heating for the future. Heat pumps, biomass, or sustainably produced gas are top candidates. But could new types of insulation or green facades and roofs not also have what it takes to put the heating issue to bed?
Super thermal insulator made from the waste product of paper production
In Osnabrück, the start-up “aerogel-it” is working on an important step in precisely this direction. It wants to bring a new generation of aerogel super thermal insulation materials to market maturity. Aerogels are a highly porous solid, the volume of which consists of up to 99.98 percent pores. Generally speaking, aerogels are not unknown in the construction industry. Insulation manufacturers like to embed them in a matrix of gypsum or cement to increase strength and durability.
The special feature of the aerogel from Osnabrück is that it requires neither petroleum nor mineral raw materials. Instead, the material is based on lignin, a substance that makes up about 30 percent of the matter of the wood cell wall and is a waste product of paper production. The biopolymer is extremely light, consists almost entirely of microscopic air pores and is therefore extremely poor at one crucial thing: transporting heat. The start-up is currently working on testing the first prototypes of the insulating materials in specific applications.
The hope is to soon eliminate a substantial disadvantage of virtually all other common natural insulation materials: Such materials made from hemp, flax, sheep’s wool, or wood fiber are indeed ecologically sustainable. But they generally have noticeably lower insulating performance than synthetic materials.
Vacuum insulation panels: A thermos for the house wall
Manufacturers of vacuum insulation panels (VIP) have long since moved beyond tinkerer status. At their core, the panels consist of heat-stable powdered silicon oxide or glass fiber, for example, which are wrapped in multiple layers of airtight foils. The VIPs obtain their strength from the existing vacuum and the pressure on the gas-tight foils. The physical principle is similar to that of a thermos flask: Where no air can circulate, no heat can be transported. The striking advantage of VIPs is that they are only a few centimeters thick, making them ideal for use in renovations where space is limited.
A look at phase change materials (PCM) also shows that the high-tech sector has been involved in efficient insulation for a long time. PCMs are latent heat storage materials that are able to store heat and cold energy for a longer period of time and then release it again without any losses. The role of the storage medium is played by salts, fatty acids, or kerosenes. When they melt, they absorb heat; when they solidify, they release the heat again. Even when heat is applied for a long time – for example, when there is a lot of sunshine and solar heating is switched on – their temperature hardly rises.
At home, this means that if the liquid-solid phase transition is approximately at room temperature, the PCMs release the heat again as soon as the temperature falls below a certain value and the materials change to the solid phase. Compared to the heat storage capacity of building materials, such as gypsum, wood, cement, or stones, PCMs store many times more heat when they melt.
Building greener: How facade greening can replace air conditioning systems
Change of perspective to the southwest of the republic, to the Stuttgart basin. Especially in such topographies, flat roofs and facades heat up strongly in the summer sun. A good portion of the energy used for heating in winter now goes into cooling the buildings. The “Helix” nursery from nearby Kornwestheim specializes in vertical greening of building facades.
For good reason, explains “Helix” building architect Jonathan Müller. “The plants and underlying construction act like a second skin. This results in a certain additional insulation performance in winter.” But the focus with facade greening is a reverse effect in summer, he says: “On the one hand, the facade heats up less, simply because less sunlight gets through due to plant shading,” Müller explains. “On the other hand, the water develops a cooling effect as it evaporates.” Together, this quickly adds up to a 20 degree lower surface temperature on the facade. “The second skin acts like a wet sponge.”
“Every degree that remains inside due to good insulation, is one degree less you have to reheat”
Mike Verhoeven, Product Manager Sustainable Building at DEKRA, on the potential of new insulation materials, as well as green roofs and facades.
Mr. Verhoeven, the republic is debating the heating revolution – simultaneously, the development of new types of insulating materials is progressing. Will we perhaps soon no longer need heating at all?
Verhoeven: The insulation values that some of these materials achieve today are indeed impressive. But houses in which small heating units are only installed for emergencies already exist: They are the very definition of a passive house. Thanks to sophisticated control technology and advanced insulation, virtually no energy is lost. The waste heat from the stove used for cooking, for example, “flows” into the house’s heating system, although that is of course not its primary purpose.
What is the potential of the new insulation materials?
Verhoeven: Their potential is by no means something to be scoffed at. In addition, the higher energy costs rise, the faster the still high costs of new developments are amortized. However, I have my doubts as to whether even the most innovative insulation can replace heating systems in our latitudes. Despite climate change, it can still get very cold in winter. In that case, the waste heat from appliances and people is not enough for a comfortable temperature. But every degree that stays inside due to good insulation means one degree less that needs reheating.
In some new developments in the insulation sector, there is a noticeable trend toward natural materials. What is the situation in terms of fire protection?
Verhoeven: The focus on renewable raw materials has great charm. The CO2 balances of synthetically produced insulation materials are not exactly among the good ones. The extent to which insulating materials may be flammable is regulated by the European standard DIN EN 13501-1 and the German standard DIN 4102-1. They serve as the basis for the fire behavior of insulating materials – regardless of whether they are renewable or synthetically produced. For this reason, polystyrene boards, a.k.a. styrofoam, must be treated with flame retardants before application, for example.
What do laymen need to consider when it comes to insulation?
Verhoeven: That depends on the depth to which someone wants to delve into the topic. Energy consultations, for which attractive subsidies are available, are a great help. Apartments and houses are very different. There are countless factors that play into their energy balance. Meanwhile, the options for insulation are just as varied. A neutral expert perspective is a great help.