EXCESS brings together 21 partners from eight European countries to showcase how nearly-zero energy buildings in four different European climate zones can be transformed into positive energy buildings (PEBs). Each of these partners brings in their unique insights and expertise into research, policy, industry, markets and innovation linked to energy efficiency in buildings, technologies, and sustainable communities.

Today, we are sitting down with Mia Ala-Juusela, Senior Scientist at VTT Finland, to talk about recent building transformation research trends, her most surprising findings and lessons learned from EXCESS, as well as changing dynamics regarding a sustainable and affordable transition of the building sector.

To start with, what motivated you and your team to take part in EXCESS and how does it link to VTT's research agenda?

I see positive energy buildings (PEBs) as a good option for improving energy efficiency and promoting distributed renewable-based energy production. These are needed for climate change mitigation and improved resilience of the built environment. EXCESS gives a wide view on the subject by looking at the issue from different perspectives and developing solutions for the identified gaps. This allows us to gain additional insights into current PEB uptake barriers and innovative new ways to solve them. Thereby, our work at EXCESS allows us at VTT to better support companies and policymakers in paving the way for a more sustainable future.

Which results from your research and work on EXCESS PEBs has surprised you the most?

I have been working on developing a common definition of PEBs experts from EXCESS, as well from EXCESS sister projects Cultural-E and Syn.ikia. In this process, we discovered that even though we had similar ideas on the general level, there were slight differences on what is included or excluded in the concept of PEB. From varying expectations regarding acceptable locations of RES facilities (on- or off-site) to which energy use types to include in the definition, there was a surpising variety how we understood the exact shaping of it.  

Building on your research and experience, what major trends will discussions around energy performance in buildings revolve around in the coming next years?

This is depending on the level and scale. On a global level, the focus is currently on finding affordable housing and building solutions, while on European level, renovation of existing buildings is another key topic. Discussion around energy justice and resilience are becoming ever more prominent as well. Slowly, also the awareness of health and wellbeing aspects started to gain awareness. So, I would say that the trend is to adopt a more holistic view, not only the operational phase energy use.

Where do we stand in moving to PEB standards?

While a wide variety of technologies is already existing to realise PEBs, there are still gaps in the implementation. This is due to a variety of reasons, such as hindering regulations or the lack of suitable business models. At the same time, innovation and new technologies are still needed, especially when it comes to storage solutions. This will allow us to widen the choice of technologies and materials, thereby reducing dependency on few and rare materials. Issues also remain in interoperability.

In the current energy and climate crisis, concepts such as renewable energy communities, nearly-zero energy buildings (nZEBs), PEBs and positive energy districts (PEDs) are garnering broader attention, which misperception would you like to debunk?

Many people raise the question of where to put all that excess energy produced by PEBs or PEDs. It is important to clarify that the aim is not to produce a lot of additional energy, but rather to support the surrounding buildings or areas on their way towards CO2 neutrality with this extra energy. It will take a lot of time to renovate all buildings to zero-energy standards and for some historical buildings this may never be possible. This is where PEBs can play a particularly interesting role providing these buildings with local renewable energy instead.

What is the next step for your research and work following EXCESS?

My research is moving towards positive energy districts (PEDs), widening the opportunities for placing renewable energy facilities and making it easier to balance the energy demand and supply from renewables at local level. This will reduce some of the challenges distributed renewable facilities pose for the current energy grids, minimise transport losses and improve resilience, as the demand side and the supply side of energy will be made closer to each other.

If you had to pitch moving into a PEB to your friends and family, what would you say?

“Move to the positive side, start sharing instead of using energy!”

More information about EXCESS partner VTT Finland and Mia Ala-Juusela:

VTT Technical Research Centre of Finland Ltd is a state-owned non-profit company, conducting applied research with over 80 years of experience, helping society and companies through technological innovation. VTT is the Technical Coordinator of EXCESS involved in wide range of tasks and with a leading role on the demonstration building projects. One of the latest outputs is an analysis of economic and emission reduction potential of renewable based energy systems in an apartment building in cold climatic conditions, presented in an IBPSA conference.

Mia is a Senior Scientist at VTT Finland with more than 20 years of experience in researching energy efficient buildings, renewables in buildings and communities.

Explore VTT work in the context of EXCESS PEBs below:

PEB definition - Report

PEB concepts for local planning instruments - Report

Positive Energy Buildings — Concepts, challenges and opportunities - Book

Challenges in reaching positive energy building level in apartment buildings in the Nordic climate - Article

Economic and emission reduction potential of renewable based energy systems in an apartment building in cold climatic conditions - Conference proceedings