Using thermal masterplanning
Thermal masterplanning helps neighbourhoods to use energy more efficiently and avoid wasting heat.
Efficient low and zero carbon energy production invariably operates most economically when applied at larger scales than the individual building. Cities offer exciting new opportunities for economic energy generation and distribution. Where people are able to live, work, study and play in a well-designed, mixed use area so ‘local’ energy loads are evened out as energy needs follow individuals around the different local buildings that are in use at different times of the day. Neighbourhoods or city quarters are a very appropriate scale at which to consider planning and designing for energy supply.
A first step in approaching a neighbourhood scale development or refurbishment is to thermally map the area. This involves identifying the existing or likely land uses and their heat and power requirements. A thermal masterplan can then create an appropriate energy strategy and a combination of energy technologies that matches the required energy demand and avoids waste heat or energy being produced. The lead client in a masterplanning process should ensure the team includes experts to inform this process and that this is programmed into the development of the masterplan at an appropriately early stage. Masterplans that form part of area action plans should seek to undertake thermal masterplanning as a core part of options development.
The local mix of building uses at a neighbourhood scale means that buildings requiring heat could use interseasonal heat storage systems to use the heat rejected by buildings requiring coolth. Interseasonal heat storage is heat storage on a large scale, which means we can collect heat in the summer for use in the winter and collect cooling in the winter for use in the summer. This technology has been used in other European countries and could be feasible in the UK. Other forms of heat pump-based systems can also allow shorter term movement of heat rejected in one building for use in another requiring heat.
The current required generation mix of electricity inherently produces waste heat that can be used in some buildings. For example, a swimming pool could source heat from a combined heat and power facility. Matching buildings that require cooling such as offices against others which need warming can be an efficient balance within a thermally masterplanned area. This is a low carbon municipal level approach used by planning authorities in The Netherlands which enables low CO2 emission cooling systems necessary for dense urban business centres to balance against increasing summer temperatures whilst also providing low CO2 emission heating.
The Dutch approach derives from a relatively simple regulation that states that over a two-year period a schememust not take or reject heat to the ground or groundwater. This means schemes always have to be designed in thermal balance and systems are always efficient without the need to be more prescriptive.
This thermal masterplanning approach is a form of industrial symbiosis. District heating can be planned efficiently alongside new electrical distribution systems (for example as part municipal-owned, part community-owned schemes, which are developed separately to the national grid) as many customers are efficiently served from relatively short runs of new distribution infrastructure. Such a system allows electricity to be sold at end user tariffs and to provide economic renewable energy to reduce impacts on values for future zero carbon building development land.
The green infrastructure network should be carefully considered alongside the thermal mapping undertaken, given its important potential role in supporting energy infrastructure and cooling the microclimate. Green infrastructure elements, particularly parks, are often surrounded by large numbers of potential customers and are also an easy ‘soft dig’ method of installing cheap, new energy distribution infrastructure, which can carry renewable electricity and low/zero carbon heat thereby delivering profit to support the management of green infrastructure and other community assets.
A new district in Stockholm which uses a community energy system and a vacuum waste system amongst other environmental innovations.
The delivery of community energy systems can only be led from a wider town planning and masterplanning level and local authorities are therefore well placed to lead on thermal masterplanning. There are a number of northern European examples of such approaches including Hammarby Sjöstad, and Copenhagen, and all have been initiated and led by the local planning authorities. Individual site scale developments are normally too small to make these systems financially viable.
As a general rule minimum housing density of 50 homes/ha average has been recommended to limit the cost of pipework installation. For new development or for buildings that have enjoyed excellent retrofits, this figure will rise as we approach 2016 as there will be less and less space heating required in increasingly efficient homes. The existing stock is the ideal customer for waste heat from CHP and district heating systems and local authorities must act as the go-between linking new development (which may be able to part-fund infrastructure systems) and the existing stock or existing industry that can use the waste heat from the CHP system.
At all scales of development, it is important to address the question of how a development will get its heating and power very early on in the design process. It becomes increasingly difficult to incorporate alternative, more sustainable solutions to energy generation later on as these decisions influence the management infrastructure and services requirements of a development. Opportunities for major public sector (particularly health or education) building projects to become community energy hubs for the wider neighbourhood should be pursued as they arise.
The Hammarby Sjöstad project piloted a new ‘Hammarby model’ for recycling energy, waste and water management, which was developed jointly by Birka Energy, Stockholm Water Company and the City of Stockholm Waste Management Bureau. The target for the project was to be twice as environmentally effective as normal new build projects in the inner city. A specific energy goal was that the entire heating supply would be based on waste energy or renewable energy sources.
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