Theme: Energy


Energy. A broad and not entirely easy-to-maneuver subject. It takes a large portion of interest as well as time to get familiarized with the different issues and to relate to the stream of important questions raised daily in media and other channels. Energy is a very important subject – not only because we rely on it for survival in today’s society but also because energy production is responsible for such a large share of global CO2 emissions. In this post, we will share some of the reasoning we brought to this project. This is a real example, how it can be done in practice.

At the start, we were to set the framework for the buildings that will be constructed in the neighbourhood Greenhouse Sthlm. We wanted all decisions to be fact-based, and decided early on to become one of the first pilots to attain certification according to the Sweden Green Building Council’s new extended certification NollCO2 (“ZeroCO2“), which is a framework standard for climate-neutral construction. NollCO2 builds on Svanen for the apartments and on BREEAM for the office extension and our goal was to achieve the level “Outstanding” (these two frameworks do not (yet) address the issue of reducing the CO2 imprint of the buildings to be built). We also reasoned that getting a high score was not our primary objective, rather, we wanted to use the frameworks as a source of knowledge. If this at a later stage would translate into high scores, that would be great! We didn’t want to score high for the sake of a high score. The scores we decided to make would reflect our ambition to really make a difference.


Life-cycle perspective

Becoming a NollCO2 pilot turned out a stroke of luck – it gave us access to a fantastic network of committed and knowledgeable people, to a lot of knowledge and we were invited to explore a framework about how to reason in order to reduce a buildings’ CO2 imprint from a life-cycle perspective. This is important and what it is all about – to raise awareness and minimize emissions from the very start and through the whole lifetime of the building. Being able to label the new buildings as climate-neutral has been secondary to us. In fact, we avoid using that word as it so easy leads to unproductive discussions about defining what is climate-neutral and what is not. We focus on what we can influence and that has been enough for us. What we do know is that the energy needed to supply a building with electricity, heat and warm water over its lifetime represents a very large share of the building’s total CO2 emissions.

Adhering to fact-based decisions proved easier said than done. Theories and opinions abound, but what makes a real difference from a CO2 perspective? We soon realized that no single framework is complete. Local considerations differ so much for different projects and the local conditions are decisive when it comes to making a real difference. We had a lot of discussions in the consulting group and a lot of calculations were made to relate to the different choices ahead, including a whole lot of Internet searching for research reports. Regardless, the certifications and framework standards serve an important purpose – they focus on the issues at hand, and increase knowledge on the individual, corporate and societal levels. They are crucial building blocks in the necessary conversion to a world where we must economize with our CO2 emissions.


District heating vs. Geo-energy?

Maneuvering the energy issue from a CO2 perspective, one needs to have reasonable insight into the overall energy system as well as some knowledge about what energy producers plan; locally, nationally, but also from a European perspective given that it is so interconnected. (Tip: Check out the app electricityMap for enhanced knowledge). In our case, we had several long and intensive discussions as to whether we should go for district heating or locally installed geo-energy with heat pumps fuelled by electricity. Here the frameworks (for example the Swedish National Board of Housing, Building and Planning, the framework standard BBR, said one thing but our reasoning and calculations pointed a different way.

On the one hand: The Stockholm district heating distributor Stockholm Exergi, with a plan for becoming climate-neutral in its operations with so called Bio Energy Carbon Capture & Storage, BECCS, technology and Carbon Capture & Storage, CCS (link to more info:  Naturskyddsföreningen(the Swedish Nature Conservation Association)), handles all our garbage, incinerates it, and creates heating, cooling and electricity. This avoids having to dump the trash that we generate in landfills for an indeterminate time (which some countries actually do – district heating is not that widespread in the world). The problem is not that our garbage is incinerated, but rather that a lot of the thrash we throw out contain fossil materials, which means that this can be compared with burning oil to heat our houses, which most people would agree is not the most optimal choice from a climate perspective. Every year, 2.9 million ton CO2 is incinerated in Sweden (Naturvårdsverket, Sweden’s Environmental Protection Agency, (statistics from 2020).


Array of factors play in

If the garbage we toss had been manufactured using 100% renewable material, could district heating then be defined as a renewable energy form…?! Here, we can make a difference. But we are not there yet, and a lot of what we buy and consume are made from fossil materials, such as plastic, polyester in clothes, etcetera. In Greenhouse Sthlm, waste separation and recycling are high on the agenda, and we aim high with the ambition to design an environmental room that will be as nice as possible and where it will be really easy to do the right thing. In the end, conscious consumption makes the biggest difference, but waste separation and recycling come in at a good second place. Here, it may be worth mentioning that as a consequence of how the BBR is written, district heating has a more negative impact on the climate than geo-energy. This is because by installing geo-energy, you don’t need to purchase as much energy. If one looks solely on the energy purchased, this is of course correct. But from a CO2 perspective, it is equally important to know when in time the energy is used, and it is also important to understand the difference between low-quality energy and high-quality energy. Geo-energy uses heat pumps that are powered by high-quality energy and uses the most electricity when it is cold and the so called power peaks usually happen – when the CO2 imprint usually is the highest (see electricityMap – free to download from App Store). The way the majority of existing frameworks are formulated, the focus is on the total energy purchased, not on how much CO2 the energy consumption generates. This makes it extra tricky to decide on which system to use, since the amount of purchased energy does not necessarily correlate with a low CO2 imprint (the CO2  imprint is also influenced by when during the day and season the energy is consumed).

High-quality energy can be used for many purposes. District heating, on the other hand, is low-quality energy given that it can “only” be used for heating. This, however, it does very well. Heat is produced (and the trash needs to be handled regardless of whether everyone turns to geo-energy) and it is topped off with bio-power (cogeneration plants that incinerate residual material from, for example, the forestry industry, this is a renewable material that “only” needs four to five generations to renew compared with fossil fuel which takes nature millions of years to recreate).


Solar considerations

What about solar cells? Solar heating? Starting out, we intended to rely wholly on solar cell panels. But the energy calculations showed that if we wanted to achieve 75% of BBR requirements related to energy, we had to include solar heating. (According to BBR, you can only count the electricity used for heating the building and for the lightning used in shared areas, which also means that it is more advantageous to install geo-energy solutions that the solar cells can power – but again, this is a calculation exercise that applies on an overall level, but not at the moment, right there, which is where we in our project relate from as we believe it is the most correct for us).

Due to shortage of space, we opted out of energy storage in this first phase. Additionally, it is still hard to justify this investment from a financial perspective. So far, the storage question is not very highlighted in BBR and the different certification standards, but we are following the market and all developments. But if you want to reduce a building’s CO2 imprint, we believe that load management to balance the power peaks is one of the most important methods.

In the first apartment building phase, we decided to add district cooling to obtain a nice indoor climate during the hottest summer days. This may sound as if we are squandering with energy, but from a life-cycle perspective we believe that district cooling, a residual product from district heating production, and thereby climate-neutral, is a better alternative than plugging in the fan during warm summer days as fans use a lot of energy. The ventilation system we have decided to install in the apartments can be controlled either through a control panel on the wall or via an app. And, Voila! The system has a smart “away mode” which means that ventilation can be reduced to a minimum when no one is home.


What is best for the planet?

As you probably have understood at this point, we had to abandon the very nice idea of relying only on fact-based decisions. Neither BBR nor the certifications standards that we decided to build in accordance with gave clear-cut answers.

So…. What did we do? We decided to go for district heating and cooling. Wastewater heat exchangers. FTX systems which recycle roughly 85% of the heat in the air. Solar heat with an accumulator tank. Solar cells on the building’s side façade and on the roof, placed on top of sedum beds which cool the solar cells and optimize their electricity production capacity (solar cells are more efficient when cooler) and that also contribute with greenery and biological diversity to the city and delays stormwater drain.

We opted for what we believe is best for the planet from a CO2 life-cycle perspective, given the local conditions related to our specific property (including the fact that we already had district heating and cooling installed in the block) and given the solutions available right now. Did we make the right choices? We believe that time will tell. Right now, we humbly and with great interest stay on top of the developments taking place in the energy market, large and small, including the development to clarify the total CO2 imprint of local energy production (few suppliers can give information how much CO2 their solar panels have caused from raw material to final product, which depends on both technique, the energy mix in the countries the components have been produced in, transport etcetera). This way we will, hopefully, make even better choices when it comes to the next construction phase which is currently being projected. We are particularly interested in the development of products that re-circulate the water in the shower, load management and energy storage in order to balance the power peaks. Small wood-built wind turbines which can be placed on the roof are also interesting! Solutions that we have looked at, and considered, but that we for different reasons didn’t go further with.


Stay tuned!

Right now, taking into account the current status and the overall plans for the first apartment phase, we have achieved 75% of the requirements regarding energy placed on new buildings by the BBR. This was the level earlier needed to obtain NollCO2  certification, but this demand has now been adjusted to the EU taxonomy. So, the requirements we earlier related to has transformed into an internal ambition. Because we believe it is right. As a small reflection, we can mention that the Svanen certification require that you reach at least 90% of the BBR’s requirements. When the City of Stockholm sells land allocations the requirement is about 75% of the BBR (55 kWh/kvm), but this is not directly comparable to BBR’s calculations since the City has adjusted the weighting a little compared with BBR for electricity used for heating and cooling. Rather than a weighting factor of 1,8, a factor of 2 is used for electricity used for heating and factor 3 for electricity used for cooling. This is probably to make geo-energy solutions more equivalent to district heating and cooling. Tough standards do good. They are important in order to make everyone stretch a bit longer and to challenge conventional and old habits.

This is how we think!


If you have any questions or thoughts about this, don’t hesitate to send us an email to

Ulrika Kågström, AB Electrolux, overall responsible for Greenhouse Sthlm property development,

Rasmus Olsen Falk, Hedström & Taube, Consultant in charge of environmental certification and carbon dioxide calculations.

Joakim Söderström, IMEK VVS Advising Engineer and Consultant in charge of indoor climate, heating, ventilation and sanitation and day-light calculations.