In our last blog we reviewed the first stage of the London Plan Energy Hierarchy, Be Lean, focusing on reducing energy demand. Now we need to address the second stage - Be Clean: Supply Energy Efficiently.
What exactly does this mean?
Given the density of development in London and the increased heating (or cooling) demand, this tier of the hierarchy is steering developers towards district heating, Combined Heat and Power (CHP) or site wide community heating. There’s a presumption that all apartment blocks and non-domestic developments will adopt one of these forms of efficient energy generation where viable. The connection of houses to a district heat network can often be considered unviable due to higher distribution losses and installation costs. Developers will need to evaluate each of the following options, before finalising their energy strategy:
- Connection into an existing district heat network.
- Future-proof the development to allow connection into a planned district heating network.
- Provide a site wide heat network with the possibility of CHP or central plant heating provision, again future proofing the development.
The focus of this section is very much to create heating networks that can be upgraded in a cost effective, low impact way should lower carbon heating systems become available in the future.
Evaluating Energy Supply Options:
1) Connection into existing district heat networks
This is a good time to introduce the London Heat Map; www.londonheatmap.org.uk This online resource carries information on existing and planned district heat networks along with future opportunities. It should be the first port of call when assessing the potential for connection to district heating networks. The Map highlights all the current district heating networks in London: The applicant must investigate the potential to connect into an existing district heat network by contacting the relevant local authority or energy operator. Evidence will need to be provided to show that this has been done and the correspondence must cover:
- Does the network have the capacity to serve the new development?
- Estimated costs and timeframes for connection.
Existing District Heating Networks:
- Olympic Park and Stratford City
- The Pimlico District Heating Undertaking
- Barkantine Heat and Power
- Whitehall District Heating network
- Bunhill Energy Centre and Heat Network
- University College London and Bloomsbury Networks
If no existing network is present, or it is not viable for financial or lead-time reasons to connect into an existing network, then the potential to connect into a planned network should be explored.
2) Connection into planned district heat networks
Again the London Heat Map is the place to go, containing details of Local Authority investigations into planned networks, examples including Vauxhall Nine Elms Battersea, The Royal Docks and Camberwell network shown below: Areas identified as potential areas for DH networks in 2010 Report by Ramboll for Southwark Council. The developer also needs to evaluate the potential of a future district heating network, even if one isn't planned. These are seen as areas of opportunity as defined on the London Heat Map: Where a development could connect to a future planned network or lies in an area of opportunity, it needs to be future proofed to allow connection into a low carbon heat source, when the opportunity arises. This includes:
- Provision of a single plant room to provide site wide space heating and hot water.
- Space identified for a heat exchanger.
- Provision made in the building fabric to allow pipes to be routed through from the outside at a later date.
- External pipework routes identified and safeguarded.
3) Site wide heat networks Combined Heat and Power
Firstly a developer must consider the viability of CHP, a tried and tested means of generating electricity on site and increasing energy security. A well designed CHP system can go a long way to reducing the carbon footprint of a development, by providing low carbon electricity generation. Some key considerations when evaluating CHP are:
- Size the system to meet base heating demand of the development to ensure relatively consistent operation. Is there sufficient heating demand to make CHP viable?
- Is the plant room large enough to accommodate the CHP unit and buffer vessel?
- Cost. A CHP system will not only incur upfront capital expenditure, but ongoing maintenance cost, both of which need to be balanced against the potential energy and fuel cost savings of the system.
- Is the local grid network suitable for electricity export when the CHP generates more power than can be used on site?
If so this will significantly improve the payback period of the system. The London Plan suggests that CHP may not be viable for developments of less than 300 units, as the associated electrify generation may not be used on site. Considering the installation of a site wide CHP network is integral to the design of the development and must be considered as early as possible in the design process.
Site Wide Community heating
As an alternative to CHP, a developer could consider gas fired community heating, with heat exchangers to each dwelling. Whilst this system doesn’t generate any electricity, upfront costs tend to be lower than CHP. This has the advantage of reducing maintenance costs for the boilers themselves, which also tend to have a higher efficiency than smaller individual boilers. In addition a community heating system will future proof a development allowing it to connect into a district heating network if one becomes available, thereby meeting the requirements of the London Plan. Once you have settled on your heating strategy for the site and established the associated reduction in Carbon Emissions, a developer must then consider renewable energy generation in order to meet the 35% reduction over the Part L 2013 TER, in order to achieve London Plan compliance. And that’s the Be Clean stage in the Energy Hierarchy. A stage that involves considerable input for investment and design be sure to review your energy strategy pre planning, to minimise the risk of non-compliance and future design changes.