In Norwegian, we usually call it a “plusshus”, and there are many different English names. For example; plus house, positive energy building, powerhouse, and so forth.
There is no common European standard definition for positive energy buildings (PEB) yet. The Energy Performance of Building Directive’s (EPBD) has a definition for nearly zero-energy buildings (NZEB), which is the standard for all new buildings from 2021. It is defined as:
A building that has a very high energy performance,[…] The nearly zero or very low amount of energy required should be covered to a very significant extent from renewable sources, including sources produced on-site or nearby.
(European Commission, 2021)
It is up to every country to specify the requirements of the NZEB standard. Thus, there can be large variations of NZEB definitions within Europe, allowing each country to adapt the definition to its local climate and context. The NZEB can be seen as the precursor to positive energy buildings.
Futurebuilt, a Norwegian innovation program promoting the sustainable, zero emission city, describes a positive energy building as «a building that produces more energy than it consumes, and defines «Futurebuilt Plusshus» as:
The energy use related to operations for the building shall throughout the year be compensated by generation of renewable energy. To account as a plus house, it needs to generate surplus energy of 2 kWh/m2 BRA (usable area) per year.
(Dokka, Andresen, Lassen, 2021,)
Further, the research project Syn.ikia’s (which I have described briefly here) defines a positive energy building (PEB) as:
A building that produces more energy from renewable sources than it consumes to achieve appropriate indoor environmental quality and cover the building energy needs (excluding plug loads). Furthermore, the PEB should contribute to the roll-out of renewable heating and energy recovery systems (solar thermal, aero/geothermal, biomass), as well as to the production of renewable electricity from different sources (solar panels, wind, cogeneration, etc.).
(Salom et. al, (2020), p.13)
The distinction between Futurebuilt and syn.ikia’s definition is the plug loads, where Futurebuilt accounts for all energy use in the building, while syn.ikia accounts for EPB uses (heating, cooling, ventilation, and lighting), which excludes equipment.
The research community is working on developing a common definition for positive energy buildings. In September 2021, during the Sustainable Places Conference, a workshop on the definition of PEB’s looked at similarities and differences of existing definitions in ongoing research projects. It resulted in a scientific article led by Ala-Juusela. The authors state that the difference between zero energy buildings and positive energy buildings is that positive energy buildings go beyond their own boundaries and provide energy to neighbours (Ala-Juusela et al., 2021). Key areas were addressed for discussion, namely the boundaries and energy balance, interaction with the grid, and social factors. The first considered what should be included in the energy balance, both the physical boundary and the types of energy consumption. The second discussion point was about the interaction between the building and the grid, and the flexibility potential of «active buildings» as opposed to «passive buildings», which only receive energy from the grid. For example, a point is to increase the utilization of the onsite renewable energy with dynamic matching of production and consumption. Lastly, the social aspect considered the user and their interaction with the building, and the indoor environment. Human centric design and user friendly systems have the potential to improve the user satisfaction. However, this can be challenging to combine with complex control strategies to reduce the energy consumption.
The discussion about a common PEB definition is ongoing, and it will be interesting to see the broadness of the final outcome.
Unit next time, enjoy the winter!
Sources:
Dokka, Andresen, Lassen (2021) Kriterier for Futurebuilt Plusshus – Revisjon Mai-2021, Futurebuilt
Futurebuilt, (accessed: 04.02.2022) Om oss (URL:https://www.futurebuilt.no/Om-oss)
Salom et al. (2020) WP3 Technology Integraiton in Smart Managed Plus Energy Buildings and Neighbourhoods, syn.ikia
Ala-Juusela et al. (2021) Workshop on Positive Energy Buildings—Definition