"The last two degrees are always the most expensive"

Interview with Dr. Wolfgang Kristinus, B+M Baustoff + Metall


When it comes to energy efficiency for residential and commercial properties, the focus is primarily on energy-saving heating. But the exact opposite is just as important: Dr. Wolfgang Kristinus, Managing Director of B+M, explains how real estate can be cooled in an ecologically compatible manner that is also pleasant for occupants.

Dr. Kristinus, do construction and real estate experts need to focus more on the question of environmentally friendly building cooling?

Absolutely. I am convinced that sustainable building cooling is even more important than the issue of heating. After all, climate change is advancing and there is hardly any other factor that causes discomfort as quickly as an overheated interior. But it is even more important to consider cooling and heating as being more closely related - also in terms of building technology. The trend is clearly toward combined systems, i.e., those that cover both applications. Surface heating and cooling systems that, in combination with a heat pump, cover all the requirements of modern living and office spaces have proven to be particularly efficient. Such heating and cooling systems are being used in more and more properties.


How do these systems work?

Unlike conventional heating or air conditioning systems, the systems work via heat or cold radiation based on the same principle as solar radiation. Compared to a cool air flow, this is perceived as much more comfortable. Neither dust is stirred up nor, for example, do mucous membranes dry out. These systems can be retrofitted in the form of a suspended ceiling both in new buildings and in most existing properties. Only a few centimetres of room height are lost, but there are also numerous advantages. First, the floor structure can be made slimmer; second, unlike underfloor heating, for example, such a system can heat and cool without the latter being perceived as unpleasant; and third, these systems are almost maintenance-free.


What are the differences in terms of the energy consumption?

The rule for any heating and cooling system is that it is particularly efficient if the supply temperatures are as low as possible for heating and as high as possible for cooling. This means that as little energy as possible has to be used - and this is precisely the case with the heating and cooling radiators. There is another advantage: the radiators heat or cool the surfaces directly and not the air first. Thus the room temperatures can ultimately be considerably higher or rather lower. A comparison can be made with a mountain climber who is illuminated by the sun at sub-zero temperatures and still feels warmth. This approach saves a great deal of energy and costs, because the last two degrees are always the most expensive. Overall, operating cost savings of up to 50 percent can be realized - with the investment costs being about the same in summary.


Does that mean it is a technology that can already be used on a large scale?

Definitely. However, if we look at the status quo, we see that there are differences both regionally and in terms of the type of use. In the BeNeLux countries, Germany and Austria, chilled ceilings for offices are now standard. The residential construction industry, on the other hand, shows a mixed picture: While newly built single-family homes are increasingly being equipped with modern cooling technologies, at least in the upscale segment, this is generally not the case for apartment buildings. Yet the question of cooling is simply a question of quality of life - which can make the difference between comfort and discomfort in everything from penthouses to socially subsidized housing units. However, more and more project developers are setting their own standards, and 6B47 is no exception: The aim is to equip all properties with modern air-conditioned ceiling systems as standard, thus always ensuring a feel-good factor in addition to high energy building standards. After all, climate-friendly construction alone does not ensure a higher quality of life - for that, it needs benefits like this that can be felt on a daily basis.


In which respect do you see an obligation on the part of construction and real estate experts to ensure higher sustainability standards?

In my view, the private construction and real estate industry is responsible for combining as many different building cooling measures as possible in a meaningful way. Examples of this are the cooling systems mentioned earlier in conjunction with photovoltaic systems or even intelligent shading that reduces the external heat load. Another piece of the puzzle is formed by smart home applications that ensure less energy consumption. The issue of so-called grey energy from building materials and transport is also extremely important. The aim must be to promote the local production of building materials in order to minimize the kilometres travelled to the construction site. A well-structured building materials trade network is also important from an ecological point of view. But there is another aspect that has so far been discussed only very peripherally: the recyclability of building materials - and not only the old materials from 40 or 50 years ago. Just as relevant is the question of current building materials, for example the sections of plasterboard and insulation materials. There, the first steps have already been taken, among other things in the form of targeted waste collection, sorted recycling and reuse. But for other building materials, we are only at the very beginning.


What can and should policy-makers focus on?

On the one hand, regulation should not stand in the way of progress - which is why flexibility is important in some respects. For example, if cooling radiators in the area of renovation fall below the permissible ceiling height for living spaces, exemptions should be possible. On the other hand, more regulation can also make sense, especially if it promotes sustainable action or penalizes non-sustainable action. At present, it still pays to transport bulky building materials such as plasterboard or insulating materials over more than a thousand kilometres to the construction site. A corresponding CO2 surcharge would make perfect sense here.