Helen Taylor from Environ offers clarification on how building energy regulations work together to improve sustainability.

Buildings have a major role to play in the fight against climate change. In the past sustainability assessment was a bolt-on factor, and uptake across the industry was patchy. Now, every development must be assessed for energy performance plus overall sustainability across the range of environmental impacts. This allows local authorities to show that new developments are in line with local and national strategies to ensure development meets these requirements.Consensus exists amongst both the regulators and those affected by the regulations on the need for a consistent approach and for simpler measurements of sustainability performance in buildings.

But there is some confusion across the industry about the relationship between the two main methodologies being applied in the UK: BREEAM (the Building Research Establishment Environmental Assessment Method) and Energy Performance Certificates (EPCs). Is there a link between the two? If so, what is it?

Absolute consistency

In fact, Energy Performance Certificates (EPCS) and Display Energy Certificates (DECs) and the newly updated BREEAM schemes for all types of non domestic building (BREEAM 2008) are consistent in how they measure carbon emissions in buildings. The Code for Sustainable Homes is a consistent part of the mix as well.

The suite of tools has been created as a result of Government’s need to comply with the EU Energy Performance in Buildings Directive (EPBD) which is intended to drive EU building stock towards lower energy consumption over the coming decades, reducing buildings’ contribution to carbon emissions.

Together, BREEAM/Code, EPCs and DECs are influencing designs towards genuinely more energy efficient and more sustainable buildings – particularly in terms of promoting a cohesive design strategy for reducing carbon emissions. This is the ultimate aim, after all: the Energy Performance Certificates, the mandatory Code for Sustainable Homes ratings for new homes, and the Display Energy Certificates (these are described as an ‘operational rating’) for public buildings.

Together, they form a subtle approach within the planning and legislative framework to driving sustainable design

(For the exact definition of the EPC rating, see box)

How do the Code for Sustainable Homes and BREEAM fit in?

BREEAM and the Code for Sustainable Homes are becoming the standard tools for local authorities to enforce a level of sustainability in new developments. An asset rating under the Code for Sustainable Homes is now a legal requirement in England and Wales for all homes sold; Code Level 3 will be a requirement on all new homes, soon.

A mandatory requirement for significant increases in performance over those required by building regulations for each Code Level reinforces pressure on developers to improve energy performance in new homes. A Code for Sustainable Buildings, which the UKGBC is currently consulting on, would respond in a similar way for all other buildings.

In the interim, BREEAM 2008 now requires mandatory improved carbon emissions for buildings gaining the higher BREEAM ratings. This addresses the often-raised concern that 'BREEAM Excellent' can be awarded to buildings with unremarkable energy performance.

It may not be immediately apparent, but EPCs, DECs, the Code and BREEAM 2008 are consistent in how they measure carbon emissions in buildings.

How hohum energy performance got a BREEAM Excellent rating in the past …

Until now, it was possible to attain a BREEAM Excellent rating without gaining any credits for good energy performance if the building did well elsewhere. This is because BREEAM evaluated performance across a wide range of sustainability considerations with no one issue being given singular importance over any other. It was only loosely coupled with energy performance. Older BREEAM schemes generally used an elemental approach to energy improvement, similar to the old building regulations.

This is changing; the BREEAM 2008 scheme now contains a mandatory requirement to address energy performance over and above regulatory compliance if a high BREEAM rating is sought (Excellent or Outstanding). For lower BREEAM ratings, mere building regulations compliance and potentially a lower than average asset rating will still be permitted. However, with the incoming Code for Sustainable Buildings, it is likely that mandatory increasing levels of energy performance over and above building regulations will be laid down, as for the Code for Sustainable Homes.

… And what's changed

BREEAM 2008 awards credits on the basis of the EPC rating. The BREEAM 2008 energy credits scale now begins with one credit awarded for an EPC rating of 63 and two credits for an EPC rating of 53. This means that under BREEAM 2008 a building which potentially achieves no improvement on Building regulations can achieve up to two BREEAM credits – but only if it gets an EPC rating better than 63. This is unlikely if it is heavily serviced, without specifying highly energy efficient services options such as active ceilings, free cooling, stack vent and so on.

The aim under this new BREEAM system is to give passively serviced buildings a head start and mechanically serviced buildings a disadvantage, making passive the preferred option. In addition, an Excellent rating is only available for buildings with an EPC rating of 40 (mid-B) or better, and an Outstanding rating can only be achieved for buildings with an EPC rating of 25 (A) or better.

How can EPCs and DECs influence the design process?

How will occupiers respond in coming years when their DEC shows D rating in their A-rated building and they have higher carbon emissions in comparison with colleagues or competitors? They will want to know why the design process, which painstakingly delivered an A-rating for energy efficiency of the building asset, didn’t include ways to make it easy for users to manage energy consumption and to monitor who’s using what.

Tenants will be asking developers and landlords to justify high rents if they discover that there is little energy metering flexibility or a low-spec Building Management System from which feedback on energy consumption in accountant-friendly formats is difficult to obtain.

Developers will be looking to their design teams to deliver energy-efficient, user-friendly services designs and control systems which link to effective, comprehensive passive measures for damping down temperature fluctuations such as automated external blinds and shading, activated vents and louvers and night cooling, thermal coupling of building mass and even clever landscape designs to shade buildings in summer.

Accountability for high energy bills and high carbon emissions will become greater with rising fuel prices and burgeoning environmental Corporate Responsibility. Everyone from the man on the street (or off the street and in the lobby looking at your DEC) to the CEO will be asking how the building is being made more energy efficient.

Gradually, as energy efficiency becomes more transparent and a desire for more efficient buildings begins to be reflected in the market, the whole procurement chain will respond with lower impact design. That, of course, is the ultimate aim of the Energy Performance in Buildings Directive, BREEAM, the Code for Sustainable Homes and sustainability assessment as a whole.

What precisely is an EPC rating?

It is important to understand what the asset rating (EPC rating) actually is, to be able to understand the link between EPCs, BREEAM and the Code drive the market towards lower energy design.

The EPC rating compares a building’s carbon dioxide emissions rate (the Building Emissions Rate or BER), calculated using the building regulations Simplified Building Energy Model (SBEM) against the Standard Emissions Rate (SER). (See box)

The Standard Emissions Rate is defined as: Reference Emissions Rate x 76.5% x 50 (the Reference Emissions Rate is the emissions rate for the Notional building but with all spaces conditioned -heated to 22ºC and with mixed mode cooling above 27ºC).

This means that a just-building-regs-compliant building with the same pattern of natural and mechanical cooling, all spaces conditioned as above, would receive an EPC rating of 50 which would place it in the lower boundary of B rating.

So, for the purposes of the asset rating, the building is being compared to a 2006-regs-compliant, glazing-and-U-values-Notional-converted, mixed-mode-cooled, all-spaces-conditioned, gas-heated-to-heating-set-point-and-electrically-cooled-above-cooling-set-point version of the building. The result is that if the building happens to have a more passive strategy than the Reference building, or has some unconditioned spaces, the asset rating may improve (even if it only meets Part L). Correspondingly, if it is a fully sealed rather than mixed mode building, it will have a disadvantage in the EPC stakes even if it improves significantly on Part L. This is because the building is being rated in terms of its asset value in a greener building market where the ‘reference’ is mixed mode. The idea of the EPC is as a tool to drive the market away from highly serviced designs and in the direction of passive strategies.