Setting Targets

Print this page

PPS1 requires local authorities to move beyond the ‘one size fits all’ approach to setting energy targets, as defined by the so called ‘Merton Rule’, and this requirement is reflected in RSS Policy ENV5. This is described as the ‘Merton +’ approach. It has two parts.

The first part of Merton + involves identifying suitable locations for decentralised and renewable or low carbon energy, using the evidence base. Decentralised energy can encompass building or site-specific technologies and larger community schemes. Planners are also asked to consider low carbon technologies, whereas the Merton Rule focused just on renewable energy.

The second part of Merton + is setting targets for renewable and low carbon energy in new developments, using two approaches:

• Area-wide targets, applicable to all developments unless subject to thresholds of a minimum number of dwellings or floor area
• Site-specific targets applied to particular sites or development areas. These can be used where feasible and viable

Planning policy targets for new buildings will be time limited, as proposed changes to the Building Regulations will require all new buildings to be zero carbon in future, incorporating renewable and low carbon energy. See role of planning.

PPS1 notes that policy and targets must be consistent with the delivery of the authority’s housing targets and not inhibit the provision of affordable housing by affecting viability. The RSS also states that targets must be feasible and viable. The evidence base should inform a feasibility assessment, while illustrative development appraisals can indicate the viability of targets. www.pas.gov.uk/pas/core/page.do?pageId=94412

Targets that are clearly and robustly defined will be easier to defend and use successfully in negotiation with developers. They will also be easier to monitor and measure against development performance.

The following issues should be considered when setting targets:

1. Defining eligible renewable and low carbon energy sources
2. Describing targets in terms of CO₂ emissions saved or energy generated
3. Measuring the baseline energy demand and emissions and savings due to renewable or low carbon energy

1. Defining eligible renewable and low carbon energy sources

See renewable and low carbon technologies for a list of the sources that may be included and technical guidance. A number of general issues should be considered when defining which will be eligible for inclusion in an energy strategy for a site to comply with local targets:

• Targets should be flexible enough to include building specific technologies as well as wider community schemes that are located further from a development, such as large scale wind farms or heat networks associated with large power stations
• Targets should encourage community networks, where several new developments may be served by a single energy centre. This also opens up the potential for new energy centres to serve existing communities and thereby lead to greater carbon reductions. Policies need to be worded and enforced with this in mind
• Area wide targets should not be prescriptive as to which technologies can be used, but should allow site-specific energy strategies to be developed that take into account local feasibility and viability
• When setting targets for specific areas or sites, it may be appropriate to specify use of or connection to an existing or proposed source of decentralised energy, where available

2. Describing targets in terms of CO₂ emissions saved or energy generated

Many current energy targets, including the one in RSS Policy ENV5, are expressed as a percentage of the predicted energy demand to be met from renewable and low carbon energy sources. It is important to consider what this means for the emissions savings that would result from achieving the target.

Each kWh of grid delivered electricity will result in at least twice the CO₂ emissions of a kWh of gas delivered. Therefore, the CO₂ savings that result from meeting 10% of the energy demand from renewable or low carbon sources, will vary considerably depending on whether they are displacing electrical or fossil fuel use (see table).

This uncertainty can be overcome by defining renewable energy targets in terms of CO₂ emissions saved. For example, expressed as:

A percentage reduction in CO₂ emissions using decentralised renewable and low carbon energy sources

The predicted annual energy demand for a site can be converted to total CO₂ emissions using standard conversion factors. It is the percentage of these total CO₂ emissions that must be met from renewable or low-carbon sources.

It is important to define the starting point at which baseline emissions or energy demands will be established. A method commonly adopted is to define this as the CO₂ emissions that would have arisen from the notional building or development if it had been designed to comply with current Building Regulations.

To encourage and account for efficiency improvements, the reductions in emissions that have resulted from planned improvements to the fabric efficiency and efficiency of lighting and other services are then deducted to arrive at an adjusted baseline demand. The percentage contribution from decentralised renewable and low carbon sources can then be measured against this adjusted baseline. This follows the energy hierarchy.

3. Measuring the baseline energy demand and emissions and savings due to renewable or low carbon energy

Planning authorities should be clear in how they define the baseline energy demand and CO₂ emissions against which targets will be measured, and the relationship between this and the requirements for Part L of the Building Regulations.

Regulated and unregulated emissions

Emissions of buildings are split between emissions regulated by Part L of the Building Regulations (those associated with the building fabric and fixed services) and those that are not (cooking and appliances).

Example of regulated and unregulated annual CO₂ emissions from a new build dwelling

The figure below shows the difference between CO₂ reduction targets expressed in terms of compliance against building regulated emissions and total emissions. It is important for the planning policy to be clear about what should be included in the baseline which renewable and low carbon energy targets are measured against, as targets relating to unregulated and regulated emissions will deliver significantly greater savings.

Comparison of pros and cons of expressing targets in terms of regulated or total CO₂ emissions:

The Code for Sustainable Homes has introduced a simple calculation procedure for determining unregulated emissions in new homes which now makes it more straightforward to set emissions reduction targets for new dwellings in terms of total emissions.

It may make sense to link any targets directly to the mandatory energy requirements for the higher levels of the Code. These targets are shown in the table below. The targets for Code levels 1 to 5 relate to regulated emissions only, whilst level 6 relates to total emissions.

There are several references that give guidance on the different renewable and low carbon energy sources and the process for calculating their contribution to emissions savings. These include:

• The Low or Zero Carbon Energy Sources: Strategic Guide, which supports the 2006 edition of Part L of the Building Regulations see:http://www.planningportal.gov.uk/uploads/br/BR_PDF_PTL_ZEROCARBONfinal.pdf
• The Companion Guide to PPS22, December, 2004, see http://www.communities.gov.uk/publications/planningandbuilding/planningrenewable
• The London Renewables Toolkit, September, 2004, see: http://www.london.gov.uk/mayor/environment/energy/docs/renewables_toolkit.pdf
• Town and Country Planning Association (TCPA) guide to sustainable energy “Sustainable Energy By Design”, January, 2006, http://www.tcpa.org.uk/downloads/TCPA_SustEnergy.pdf

Further information is also provided under technical guidance.