By the end of 2020, all new buildings must be almost zero-energy. This means buildings that consume very little energy. In addition, the energy required should be renewable as far as possible. Where this renewable energy would best and most sensibly produced is up for grabs. If the energy is produced locally to fulfil, say, the needs of entire neighbourhoods, huge benefits can be reaped without placing unreasonable demands on single buildings.
A range of zero energy solutions have been proposed and analysed by the international scientific literature, but few have been implemented. In my opinion challenges in implementation, such as high costs or complex system solutions, may be the reason for this. The more systems there are, the more demanding their use and maintenance is. Such barriers are lowered if zero-energy areas replace zero-energy buildings.
Local renewable energy sources can be chosen in order to improve an area’s energy self-sufficiency and emission reduction. In densely built areas, it makes sense to design buildings that serve as an effective part of the local energy system. For example, solar energy systems can be placed optimally with respect to the entire area, to avoid shade due to differences in altitude, or to trees or other buildings. In Germany, solar thermal collectors intended for residential heating are installed e.g. as roadside sound barriers and roofs for parking facilities.
Sweden, Denmark, Germany and Canada implemented local, solar thermal systems combined with district heating and seasonal storage years ago. Pilots for the seasonal thermal energy storage (STES) of solar energy on a local basis are few and far between in Finland, despite demonstrations by international studies that the utilisation level of solar energy can exceed 50% of the annual local heat requirement in similar climate zones. STES can also be enhanced through the more effective use of a variety of waste heat solutions, such as excess heat from data centres.
Greater use could be made of local renewable energy, waste heat and heat storage if district heating networks were opened out to a range of heat producers. This has been done in Stockholm. New players and competition thereby enter the heat production market. At the same time, energy flows can be recycled and local energy efficiency improves.
A recently completed study by VTT presents options for heat and power generation based on local energy systems. Energy needs and ‑production on Vartiosaari in Helsinki were explored as a case area. The project studied the impact of introducing solar thermal energy on local self-sufficiency and emissions from heating energy, if excess solar heat in the summer is stored using BTES (borehole thermal energy storage) or tank-based storage for use in the winter. Around 60% self-sufficiency in heat production would have been achieved in the cases studied. In addition, carbon dioxide emissions could be reduced by around 50%, and sulphur dioxide and particulate emissions by up to 70%.
Read the publication “Paikallista energiaa asuinalueella – Esimerkkinä Helsingin Vartiosaari” online.