Forward planning

Planners and services engineers have been on a steep learning curve since the London Mayor introduced requirements for renewable energy to be integrated into developments.

Planners in the capital, and elsewhere, are now looking for sustainable energy considerations to be a component of all major applications, including an assessment of options and a recommendation of the most feasible and suitable package for the site. And it is services engineers who are best placed to offer architects and developers this advice.

There is much for planners and consultants to understand if the transition from scheme concept to completion is to be a smooth one - but don't fret, help is at hand. A project set up by the London Energy Partnership called ‘Capacity Building on Sustainable Energy Planning Policy' aims to ease implementation of these policies by helping to smooth negotiations between planners and engineers.

For the project, Faber Maunsell SDG worked with five London boroughs (Enfield, Greenwich, Hackney, Haringey and Tower Hamlets) on five planning applications, of a size and type likely to be called in by the Mayor, including residential, educational, office and mixed-use schemes.

The aim was to capture the essence of the discussions and negotiations, so planners could learn from their colleagues and a consistent approach be developed for applications.

The main finding was that engineers were not submitting sufficient information for planners to make an assessment of a scheme. And there was great variation in the level of detail and quality of energy strategies, also called assessment reports.

Many designers had failed to convert the energy demand of the site in gas and electricity into carbon or carbon dioxide emission terms, necessary to compare electricity and gas use, and savings, on equal terms. Not all had included total site energy demand; for example, external and car park lighting and others outside Building Regulations control.

Most designers had used benchmark energy demand figures, not modelling-based calculations, due to the early design stage reached.

All designers had proposed various energy conservation measures that were intended for the development, such as improved insulation and infiltration levels, and efficient HVAC plant and controls - but the actual impact of these on carbon dioxide emissions was not always calculated. Sometimes, a number of energy-efficient design options were described in detail without specifying which had been selected for the development in question. District heating and CHP were mentioned for all developments. But they tended to be dismissed, without a study of the effects on carbon dioxide emissions, by saying there was not sufficient year-round heat demand.

This may be true, but the reports lacked the calculations to adequately dismiss the options.

All energy assessment documents submitted gave a review of the renewable energy options for the development, but as vague statements, without detail of size, location or output of systems. Ground-based heating and cooling, PV, solar water heating (for housing), biomass heating and wind were all proposed, though no strategy gave a definitive commitment on what technologies would be used.

Must try harder

It is vital engineers carrying out energy assessments take a more comprehensive approach to renewable energy, and to helping planners understand energy in planning. In future they will have to because Faber Maunsell told planners to insist on this. Energy strategy contents in the box (pictured) show what's expected.

The project also involved working with the London borough of Brent to provide input into the preparation of a Supplementary Planning Document (SPD) for a major site. SPDs are used to elaborate on policies and proposals contained in a development plan document. The full SPD for Brent is now publicly available and covers requirements of the London Plan and the Mayor's Energy Strategy, the borough's views on district heating and cooling networks and CHP suitable for the site, and the required content of the Energy Strategy for energy efficiency and on-site renewable sources.

The inclusion of energy requirements in SPDs is likely to become the rule, and clear guidelines to help engineers make applications that include adequate energy strategies will speed up one aspect of the planning process.

What next?

The work with planners showed that previous training and publicity about energy in applications had not permeated to all planning officers. But, even if planners were energy literate, the quality of energy strategy documents was inadequate for them to determine compliance with the Mayor's Energy Strategy.

Practical assistance for designers is on its way. The London Energy Partnership is commissioning work to develop an electronic toolkit for low- and zero-carbon developments to build on the London Renewables Toolkit. It is likely to include calculation programmes and data tables for use by designers and others to aid the design of sustainable energy strategies.

But to really cut carbon dioxide emissions, energy strategies must be far more accurate, clear and capable of implementation. And that's up to you, the engineers.