Evidencing a local plan renewable energy target

A local plan renewable energy target looks like arithmetic and is usually a drafting exercise. Whether a scheme meets a policy requiring, say, a proportion of energy from on site renewable sources depends on what the policy measures, what baseline it measures against, and whether its feasibility caveat has been engaged with evidence rather than asserted. Get the reading of the policy wrong and a compliant scheme is reported as non compliant.

Start with the words, then the baseline, then the caveat. In that order.

Reading the policy wording precisely

Policies of this kind vary in four ways that change the answer.

What is measured. Energy, expressed in kilowatt hours, or carbon dioxide emissions, expressed in tonnes or kilogrammes. A policy targeting a percentage of energy from renewables is satisfied differently from one targeting a percentage reduction in emissions, because a heat pump running on grid electricity reduces emissions substantially while generating no energy on site.

Which energy. Regulated energy, meaning the fixed building services covered by the Building Regulations calculation, or total energy including unregulated loads such as appliances and lifts. The difference is large, and policies are often silent, in which case the supporting text or the authority's own guidance usually resolves it.

The baseline. Against the notional building in the current Part L calculation, against a stated earlier edition, or against a fixed figure in the policy. A target expressed against a superseded edition of Part L is a common drafting artefact in older plans, and how the authority treats it is a matter to settle at pre application stage.

And whether the requirement is absolute or qualified. "Development will provide" reads differently from "development will provide where feasible and viable". The second is the wording that most plans use, and most of the argument happens there.

The statutory basis for these policies is section 1 of the Planning and Energy Act 2008, which permits a local plan to include reasonable requirements for a proportion of energy used in development to be energy from renewable sources in the locality. Note the words "in the locality", which is what allows some authorities to accept off site provision.

Percentage targets and what they measure

Once the metric is settled, the calculation is mechanical, and the useful discipline is to show it as a table rather than a narrative.

Two traps. Quoting installed capacity in kilowatts peak as though it answered a question about energy, when the policy asks for a proportion of annual demand. And reporting the percentage without stating which denominator was used, which makes the figure unverifiable.

Name the software and its version. Assessment tools are updated and emission factors change between versions, so a figure without a version is not reproducible.

Feasibility and viability caveats in policy

The caveat is the most litigated part of these policies, and the reason is that applicants treat it as an exit and authorities treat it as a test.

A caveat requiring measures "where feasible" asks a technical question. Is the technology capable of being installed on this site, given the roof area, orientation, shading, structural capacity, grid connection and any constraint on the building. A caveat referring to viability asks an economic question, and on a scheme where other obligations are being negotiated it interacts with the wider viability position.

The distinction matters because the evidence differs completely. Feasibility is demonstrated with drawings and calculations. Viability is demonstrated with an appraisal, prepared to a recognised methodology, which the authority may have independently reviewed at the applicant's cost.

Do not conflate them. A statement that a target is "not viable" supported only by a roof area calculation will be read as a feasibility argument dressed in economic language, and an officer will ask for the appraisal.

Evidence needed to rely on a caveat

Relying on the caveat is legitimate. Relying on it without evidence is what loses applications.

For a feasibility argument, the material that works:

• a roof plan showing the usable area after rooflights, plant, access zones, and any green roof required by other policies
• orientation and pitch of each roof plane, with a shading analysis across the year
• a structural note on the capacity of the roof as designed
• the distribution network position where the array size approaches a connection threshold
• for heritage constrained buildings, the conservation position on visible installations
• an appraisal of each technology considered, with the reason each was excluded

That last item is the one officers look for and rarely find. A statement that photovoltaics are the only option considered, with no mention of solar thermal, heat pumps or a roof mounted alternative, reads as a decision taken before the assessment.

For a viability argument, the appraisal needs to be prepared to the recognised professional methodology and to isolate the cost of the renewable measures from the other matters in dispute. Where the scheme's viability case is being tested anyway, fold the renewable requirement into that exercise rather than running a separate argument. Phased sites raise their own sequencing problem, dealt with in our note on energy masterplanning on a phased site.

Interaction with national standards

Two points of friction recur.

Building Regulations set the minimum, and successive uplifts to Part L have narrowed the gap between national requirements and local targets. A scheme meeting the current Part L may already satisfy a local percentage target written against an earlier edition, and saying so with the calculation is the cleanest route to compliance.

Government has also periodically restricted the extent to which local plans may set energy standards for new housing beyond national requirements, through written ministerial statements, and the position has been revisited more than once. Where a policy predates such a statement, its status is a matter of argument rather than arithmetic, and the safe course is to demonstrate compliance on the numbers where you can and reserve the policy argument. Check the current position at the time of the application rather than relying on a precedent.

Recording the assessment for the officer report

Officers lift material into reports. Give them something liftable.

1. A one paragraph statement of the policy requirement, quoting the operative words.
2. The metric and denominator used, stated explicitly.
3. The results table, with the percentage achieved.
4. Where a caveat is relied on, a single paragraph identifying which caveat and summarising the evidence.
5. A cross reference to where each piece of evidence sits in the submission.
6. A conclusion in the author's own words on whether the policy is met.

That last point is worth insisting on internally. A document that lists figures without concluding leaves the officer to reach the conclusion, and an officer under time pressure who cannot find a conclusion sometimes writes that the policy position is unclear. The narrative belongs in the Energy Statement, with the broader policy coverage in a Sustainability Statement.

Where targets conflict with heritage or amenity

Some sites cannot meet the target without breaching another policy, and the honest submission says which.

Photovoltaics on the principal roof slope of a listed building, or on a prominent roof in a conservation area, engage the statutory duties on listed buildings and conservation areas, and those duties are not displaced by an energy policy. Similarly, plant sized to meet a renewable target can create a noise or roofscape problem that the amenity policies resist.

Where that happens, set out the conflict rather than ignoring the weaker policy. Identify the two policies, explain the physical constraint, state what the scheme does instead, and let the decision maker balance them. That is what the plan expects of a decision maker, and it produces a defensible officer report. External insulation raises the same tension on historic buildings, covered in our note on external wall insulation in a conservation area.

PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval. For specialist technical reports, qualified professional input may be required, and compliance calculations need a competent assessor. This is general guidance and not legal advice, so check the position with your local planning authority or a qualified professional before relying on it.