The topic and connections are complex. New keywords and little-known terms frequently pop up and there are constantly new developments – not only in response to public and political pressure.
In this new section we will show you which opportunities we know of within our field of expertise and, by means of positive examples, that these opportunities can be used to bring about the positive, impactful change we need.
– We call the beginning Chapter 1.
Can all existing buildings achieve climate-neutral status by 2050?
What can we do against climate change? One answer is to design and build climate-neutral buildings. In 2012, the year of our 15th anniversary, we began asking ourselves the question: Is it possible to have all climate-neutral buildings by 2050? We already know that there is no alternative if we want to limit climate change to +1.5 degrees Celsius.
Current figures still show that about 40% of CO2 emissions are caused by the construction sector. This includes not only the operation of buildings, including what the occupants are responsible for (such as heating, cooking, washing etc.) but also the emissions that occur during the production and transport of building materials and equipment in buildings.
There are several ways to set-up balance sheets for buildings: They differ in their system boundaries. The building owner is challenged and needs to consider how ambitiously he should strive for the goal of „CO2 neutrality“. Does he/she want the building to operate free of CO2 or does he also want to ensure that the building itself does not have any climate-damaging influence? Should the CO2 emissions for the mobility of residents or employees be taken into account? Does he/she want to go beyond that and at the same time do something to counteract global warming? By exporting energy to the electricity, gas, district heating or district cooling network or by binding CO2 in building materials, can additional CO2 be saved, and can the building thus become climate-friendly?
Is neutral not neutral?
Neutral in the physical sense means neither positive nor negative, always based on a spatial and temporal balance. Applied to building, the spatial balance limit is typically the property boundary; energy flows or associated or avoided emissions are balanced over one year. This means it is sufficient to offset energy consumption or emissions in period 1 with credits in period 2. However, this also poses a problem at the same time: Credits are generated when renewable energy is exported to an existing energy network beyond the property boundary and avoids „external“ generation of the same amount of final energy elsewhere that is currently still associated with conventional primary energy sources and high CO2 emissions. Thus, there is no longer a credit if the external generation of the secondary energy sources (final energy sources) electricity, gas, district heating or district cooling is also 100% renewable. But even if this is the case by 2050 at the latest, the following challenge still remains: where to put all the exported surpluses of the individual plots of land if they occur at the same time?
It therefore seems sensible not to misuse energy networks arbitrarily as „ideal energy stores“ in balancing, but to maximize the local energy self-sufficiency of a property. Clearly, this is easily possible in the countryside with relatively flat buildings but is extremely ambitious in existing cities with multi-story buildings and mutual shading. Therefore, it seems sensible to minimize the energy requirement in each individual case and to make the best possible use of the local potential of regenerative energy generation in order to be able to become neutral in the aggregate.
Clarifying the term „climate positive”
Actions and processes that release greenhouse gases have a reinforcing effect on the global climate crisis, i.e. in simple terms they have a „climate-damaging“ effect and are therefore negative. In contrast, actions and processes that are not linked to greenhouse gas emissions have no effect on the climate. This also applies if (temporary) emissions are balanced, fully compensated for over a year; net zero-energy buildings are considered CO2-neutral in operation, which can also be assessed as climate-neutral or greenhouse gas-neutral.
In variation of this, the term „climate-positive“ has been established for actions and processes that counteract global warming, i.e. are good for the climate, or even mitigate harmful influences of others. This can be a building that generates more electricity than is consumed inside (net-plus energy building) - or outside the building world, a greening or reforestation measure.
Working towards solutions — climate-neutral or climate-positive design
Let‘s build a house with a garden for the ideal client, who wants the project to be at least climate-neutral. Such an endeavor might seem manageable because the possibilities of influencing the building materials and the equipment of the house are ideal. After determining the energy consumption for light and heat, we find the ideal locally accessible regenerative energy sources. Of course, we also balance the installation and equipment for energy production. It is quite logical to compare the feeding of temporarily surplus electricity into the grid with the consideration or possibility of local storage. The result could be a climate-neutral, even climate-positive single-family home. A net zero energy building, because its energy balance is balanced; it does not consume more than it generates. It even makes it possible to generate more energy than is needed over a balance period of typically one year, as it is called a net plus energy building.
Similarly, this can also be applied to the refurbishment of an existing building, which is already more difficult because, for example, the location and orientation of the building is predetermined, the substance of the building must be analyzed and possibly improved, or sometimes monument protection limits the possibilities.
If we now take a big step further and consider an apartment building or apartment blocks as an example, it becomes clear that there is an increasing shortage of space on the roof if photovoltaics alone is to supply energy there. There is a lack of regenerative energy; it has to come from the outside. In the ground, for example, heat and cold are available free of charge; they must be tapped and made usable via heat pump, e.g. by driving with solar power. However, the regenerative electricity cannot be generated on the property at any time in our latitudes and is therefore imported from the public power grid.
There are even more advantages to a planned urban (partial) development: Synergies can be exploited, local solutions can be created, energy supply systems and their potential can be analyzed, local heating networks can be laid for infrastructure measures — also as a precautionary measure — and, where possible, roof areas can be optimally positioned and those in the neighborhood, e.g. those of multi-story parking garages, can be covered with photovoltaics to supply the surrounding area with electricity.
Heat recovery and demand-driven ventilation, plus passive cooling, an efficient combination of strategies that is particularly suitable for buildings where sometimes there are many people — and sometimes none: schools, ballrooms, open-plan offices. Excess (waste) heat can also be stored for the winter. When operated on a large scale, this is particularly worthwhile.
All the strategies briefly mentioned here are approaches that will make it possible to mistreat the world atmosphere less in the future.
Possibilities are therefore available. The basic prerequisite for their success is that someone must want them, and that is the client or investor. Not return on investment should be the top priority, but sustainability.
For a municipality, for example, this means that it needs the opportunity not to award the contract to the cheapest concept, but to be able to vote for a sustainable solution.
„The CO2 emissions caused by the building and its use must be lower than the emissions avoided by the building’s own production and export of greenhouse gas-free energy“.
With „climate-positive“, the DGNB has created a clear term as a new rating for buildings and awarded it for the first time in autumn 2019. The society uses it to award buildings that, to put it casually, demonstrably „generate more output than they consume“ during operation and uses the equivalent CO2 emissions as an assessment yardstick as follows:
„The CO2 emissions caused by the building and its use must be lower than the emissions avoided by the building‘s own production and export of greenhouse gas-free energy“.
Real measured energy consumption figures must be available as a basis for this and the predicate is valid retroactively for one year only, because the quality of energy imports over the property boundary has been contractually agreed and may change. However, only buildings for which the values can be reported can be submitted for evaluation. Building owners, operators and users must therefore participate, consumption values are subject to data protection. An apartment building, for example, can therefore hardly be submitted. However, due to the real data, the award is transparent and based on reality. And with the annual deadline, self-regulation remains attractive, and any changes are taken into account.
In 2019, six of our projects received this DGNB award. If possible, we will continue to monitor the operation of the buildings that have received the award to date, look forward to extending the list with additional buildings by means of further annual results and thus look to the future in a „climate-positive“ manner.