Living by the rules

ith the inexorable expansion in energy and carbon-related rules, regeneration projects are becoming ever more complex, and require an ever more structured approach to energy provision. And as project can last up to 15 years, the current trend of revising planning and building control requirements on a three-to-five year cycle means that a long-term energy view is required from the inception. We present a five-step approach to today’s legislation that should help to control costs and manage risks throughout the design development process.

Stage 1: Options appraisal

Large-scale estate regeneration projects demand a considered approach to sustainability from the outset, irrespective of whether renewable energy is required. At the feasibility and options appraisal stage, redevelopment scenarios should be drawn up by the architect and costed by the QS, with the preferred option being presented to residents for consultation. The energy considerations at this stage include evaluating whether on-site renewable energy is required as a planning condition, or whether it is likely to come in as a requirement later.

If this is the case, a preliminary space planning and budgeting exercise is required to inform the options appraisal process. This study should consider issues that affect the options appraisal process, principally budget and space-planning, for example, whether a district heating network is likely to be required and what the budget costs for renewables are.

Action

• Undertake preliminary space-planning and budgeting for renewable energy provision

Stage 2: Outline planning

Once a preferred outline has been selected and approved by residents, an estate-wide masterplan can be produced for outline planning application. This will detail massing, heights, form, uses and overall quantity of units and the Greater London Authority would require an energy assessment as well as an energy strategy.

At this stage, benchmark figures for CO2 emissions and energy use are sufficient – more detailed, site-specific studies can be undertaken at the next stage, when more precision is required. Energy efficiency measures should be appraised as well as non-renewable low carbon technologies such as gas-fired CHP and heat recovery.

Actions

• Ascertain CO2 emissions
• Undertake energy efficiency and low carbon technology appraisal
• Undertake full renewables options appraisal
• Submit energy strategy with planning application

Stage 3: Detailed planning of phases

Once the masterplan has outline planning permission, detailed planning consent can be sought on a phase-by-phase basis. At this stage, it is worthwhile to undertake a Part L 2006 risk analysis as it can affect the aesthetics and the budget of a project. A dwelling will fail if it emits too much CO2 but also if it is will overheat – a pertinent issue considering the temperatures experienced this summer. The risk analysis comprises a few SAP calculations of dwelling types and SBEM for the non-residential elements. Interestingly, if communal spaces in residential buildings are heated, Part L2a will apply.

This exercise also provides a more precise calculation of the phase’s CO2 emissions, informing the detailed energy strategy for the phase. This is essentially a refinement of the energy study at outline planning stage, setting detailed layouts, servicing arrangements and budgets. Should a particular EcoHomes rating be a requirement for planning or funding, the uplift in energy and carbon efficiency from Part L should be quantified and budgeted for – up to two credits are awarded for improvements in insulation over Part L and up to 15 for the overall CO2 emissions performance. Refurbishments are assessed using the same EcoHomes methodology, although slightly different criteria apply to some credits.

Soon, the Code for Sustainable Homes is set to replace EcoHomes and will set minimum energy performance criteria above Part L.

Actions

• Part L risk assessment
• Refining renewables quantity, budget and integration into design
• Preliminary EcoHomes assessment

Stage 4: Building control submission

Attaining detailed planning consent moves the project swiftly on to dealing with the legislative aspect to building, more formalised and defined perhaps than the policy side of things. Full design-compliance with Part L must be demonstrated through submission of SAP and SBEM calculations. Note that blocks of flats may be assessed on an individual basis or a whole-building method.

It is at this stage that the full EcoHomes assessment should be completed and the detailed design of the renewables system takes place. One of the issues with the provision of renewable energy is that from the end of the planning stage, there is no further policing of the implementation – this means that in theory, biomass boilers may be installed yet left idle.

Generally, the 10% renewables provision is not counted towards the Part L CO2 calculation – that is, the CO2 savings achieved by renewable energy should be separate from those achieved by Part L, although again, this can be a grey area if poorly understood by the local authority.

Actions

• Undertake full SAP calculations
• Submit design SAP calculations to building control
• Undertake full EcoHomes assessment

Stage 5: Construction phase

Lastly, there are several measures that must be undertaken at the construction phase to ensure that the Part L design performance is met in practice. The most tricky is perhaps the pressure test – for this reason, it is worth undertaking some tests on the first completed units prior to the testing for Part L to shed light on potential construction errors. These can then be monitored during the construction of later units.

Actions

• Confirm that building is built to standards set out in design
• Fill in “key features” checklist
• Confirm use of accredited details
• Undertake site inspection
• Undertake pressure test