Plus Energy Buildings are designed to generate more energy than they consume. This extra energy can be shared or sold, often as part of an energy community.
To achieve this, the energy generated on-site must be greater than the total energy used by the building, including all house appliances and plug loads. This concept is well described by the formula:
PEB balance: Energy Generated - Energy Used > 0
The Energy Generated is the total primary energy generated onsite.
The Energy Used is the total primary energy load of the building. This includes the energy used for heating, cooling, ventilation, lighting, domestic hot water, house appliances and plug loads.
If the energy generated onsite is higher than the energy load of the building over a time span of 1 year, the building qualifies as a Plus Energy Building.
To produce energy, Plus Energy Buildings rely on renewable energy systems like solar panels or wind turbines. These systems must be located on the building's property or nearby areas that are physically connected and under the same ownership or management.
Evaluating technologies for energy efficient buildings
In the project Cultural-E researchers analysed different technologies and building systems to assess their energy use, costs, and environmental impacts. This study focused on two types of multi-family buildings:
- a compact 8-story high-rise
- a 3-story low-rise apartment building.
The analysis was conducted in four distinct climate and cultural regions: Mediterranean, Oceanic, Continental, and Sub-Arctic. For each case, the size of the building’s photovoltaic system and battery storage was optimized to balance economic performance and energy flexibility.
What emerged is that there are several challenges to achieve positive energy balance:
- Despite low operational energy needs (heating, cooling, ventilation, etc.), the high energy consumption of household appliances often exceeded what could be offset by on-site renewable energy systems.
- In compact or high-rise buildings, the smaller roof area per apartment limits the feasibility of on-site renewable energy production.
Solutions proposed include:
- Reduce appliance energy use and inform residents to use energy more efficiently.
- Add PV systems beyond the building’s roof, such as on nearby structures or shared solar farms.
The factsheets developed in the Cultural-E project provide a comprehensive evaluation of solutions to reach Plus Energy targets, to offer building designers, architects, engineers, and stakeholders a clear understanding of the performance and sustainability of these solutions over a 30-year period.
They detail energy consumption, indoor environment quality, life cycle costs, and environmental impact, combining data from energy simulations, LCA and LCC analysis.
