Catching up with Part L

Published:  06 January, 2014

Part L 2013, Building Regulations

2013 was nearly over before the 2013 edition of Part L finally arrived. It continues to raise standards, but not by much, and attempts to pave the way for future changes. Ken Sharpe has been finding out more.

Although carrying a 2013 label, the latest Part L of the 2013 Building Regulations (for England at least) will not come into effect until 6 April 2014 — and it will probably be well into 2015 before there is any significant effect on actual buildings. The availability of even online documentation was delayed several times, and CIBSE’s technical director Hywel Davies reminded the recent ICOM winter conference that 15 months passed from the end of the consultation for the 2013 changes to the regulations themselves. Indeed Hywel Davies believes the regulations could have been available much earlier.

The underlying principle of successive editions of Part L, which is concerned with the conservation of fuel and power in buildings, is progressive reductions in energy consumption and carbon emissions. They are not the same thing, as Ant Wilson of AECOM explained during a webinar organised by the Building & Engineering Services Association. A recording of this webinar is available on the B&ES web site (Google B&ES webinar Wilson).

He explained that Europe requires ‘nearly zero energy’ buildings from 2019 and that this position is already set out in our Building Regulations.

Hywel Davies also draws attention to this point, which is covered by Regulation 25B stating, ‘Where a building is erected, it must be a nearly zero-energy building.’ He reckons this provision will not come into effect until 2020 and that its existence now is to be able to say to Brussels that the UK Government is doing something.

Ant Wilson explains, ‘Nearly zero energy is very difficult and very different from zero carbon, which is achievable, but expensive. A zero-carbon building, however, might still use lots of energy.’

The policy decisions behind Part L 2013 were explained by Paul DeCort of the Department for Communities & Local Government at the recent NBS Live event. The principle is to strike a balance between green and growth policy ambitions. The green ambitions include a meaningful step towards zero carbon and reducing energy costs for consumers and business. Growth ambitions are governed by the Spending Review 2010 commitment and a ‘one-in, two-out approach to regulation’.

As with previous editions of Part L since 2002, carbon emissions are being reduced, but it is recognised that there are many different types of building — both in the domestic and non-domestic sectors. There is accordingly not a one-size-fits-all approach.

Instead, the uplift in improving the energy performance of new buildings varies widely. For non-domestic buildings (non-dom) the smallest improvement is for small warehouses — just 3%. The biggest uplift is for shallow-plan offices (13%), with deep-plan air-conditioned offices and hotels close behind at 12%. The logic is that it is easier and more cost effective to achieve reductions in energy consumption in some types of building than in others. The requirement for seven building types is summarised in Table 1.

For non-domestic buildings, the intention is that the aggregate uplift in energy performance across the build mix will be 9%.

The target that came out of the consultation document was a substantially higher 20%, as CIBSE’s technical director Hywel Davies observed at the recent ICOM winter conference.

The final 9% target has been described by various Government spokespeople as striking a balance between green and growth policy ambitions. They include Paul DeCort of the Department for Communities & Local Government at the recent NBS Live event, Anthony Burd, head of technical policy at DCLG at the ‘launch’ event at BRE in October. Ken Bromley, senior technical policy office with DCLG, also presented the same thinking to the ICOM winter conference.

Much less of a drop from the consultation is the 6% uplift for new homes — the figure in the consultation was 8%. That 6% is also an aggregate figure across the building mix, depending on whether the home is a detached house, in a terrace or in an apartment block. As for non-domestic buildings, the target figure is to strike a balance between progressing to long-term green objectives and not jeopardising growth.

Hywel Davies is not so sure that the two objectives are really different. He said at the ICOM conference, ‘The Government has a huge tension between balancing growth and reducing the regulatory burden with being green.’ He referred to the requirement for new and replacement boilers to be condensing boilers, asking, ‘What is the difference between the burden of regulation and growth?’

Figures in Ant Wilson’s webinair suggest that the 9% upgrade for non-domestic buildings would achieve energy savings of £604 million for incremental costs of £604 million. The 20% upgrade would more than double the energy savings to £1302 million but increase incremental costs even more to £1485 million. There are clearly issues of who pays for improved energy efficiency and who benefits from it. There is also a likelihood that the incremental costs of improving energy efficiency could fall if efficiency measures are more widely applied.

So now that we actually have a new Part L, what is actually required?

Part L 2013, Building Regulations

For new homes, an elemental recipe has been introduced that will provide a compliant solution. The recipe is based on an up-to-date fabric and service specification with no improvement factor. The notional dwelling is the same shape and size as the actual dwelling and based on a set of current fabric and service specifications.

However, as Ant Wilson explains, the recipe is not prescriptive and may not be the most cost-effective solution for all projects. The recipe is intended to provide a reasonable starting point for builders to develop their own solutions.

Suggestions put forward for an end-terrace house include installing triple glazing while relaxing the U-values for external walls and floor; air tightness can also be relaxed. The addition of waste-water heat recovery while relaxing fabric standards is also suggested.

Likewise, a suggestion made for a detached house is to relax fabric standard and include solar hot water.

Moving on to new non-domestic buildings, there is a wider range of concurrent notional buildings than for previous editions of Part L, including modifications for smaller warehouses. As for new homes, the concurrent specification is compliant with CO2 targets and backstops; it therefore provides a reasonable starting place but is not prescriptive. Compliance with Part L will generally be achievable through good fabric and services.

There is also scope for more-imaginative solutions, provided backstops are observed.

Lighting is a case in point. There are two categories to compliance. One is to achieve an installed load of 60 lm per circuit watt, up from 55 lm per circuit watt. The other route to compliance is to adopt LENI (Lighting Energy Numeric Indicator).

The LENI approach makes it possible to take into account how lighting is actually used, not just the energy used by lamps when they are on. Controls come into prominence, both to dim lights in response to available daylight and to turn them off if no-one is around. And there are plenty of people in the lighting industry holding the view that there is more to energy to be saved from controlling lighting than further pushing efficiency requirements for lamps and luminaires.

Given sufficient control, a lighting efficiency as low as 42 lm per circuit watt is permissible. That level of control requires daylit spaces to have photo-switching and dimming — with or without over-ride — and for lighting in unoccupied spaces to be switched on manually and off automatically.

The importance of controls in general was remarked on by participants in the B&ES Webinar. It was noted that ‘fixed building services’ now includes controls, which is a major change in the definition of fixed building services.

For non-domestic controls, the 2013 update to Part L recommends that building services are provided with control that as a minimum correspond to Band C in BS EN 15232:2007 ‘Energy performance of buildings — impact of building automation, controls and building management’. You can find various articles relating to this standard on the MBS web site by searching for 15232.

This standard has four classes of building control, and Class C is regarded as ‘standard’. The more advanced controls required for Class B will reduce energy consumption by 9% (hospitals) to 27% (retail). Class A will achieve 14 to 40% savings compared to Class C. The improvement for offices from Class C to Class B is 20% and 30% from Class C to Class A. The savings to be gained from improved control of building services are very substantial and emphasise the much argued point that equipment efficiency must be complemented by system efficiency.

And finally, what about Part L for existing buildings — L1B AND L2B? A press release from BSRIA is quite succinct: ‘Changes to the Approved Documents for existing buildings are minimal. So much so that they have been issued as an amendment slip. We are, however, assured that consolidated versions of these Approved Documents will be issued before they come into effect on 6 April 2014.’

BSRIA runs Building Regulations training courses. There is an introduction to the regulation on 12 March and a course on understanding Parts L and F on 25 February (Google BSRIA events).

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