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The case for action – defining zero carbon in non-domestic buildings – our views

February 2014

The long journey to zero carbon in the UK saw another milestone as the UK-GBC launched a consultation on the zero carbon definition for the non-domestic sector at the start of the year.  With this initiative, the UK-GBC zero carbon task group was looking to gather wider industry feedback on its thoughts and proposals and feed into the on-going discussion on the energy policy road map.

At XCO2 we were keen to take part and gladly submitted a consultation response. This post presents our reflection on some of the hot topics concerning the zero carbon definition.  Yesterday UK-GBC launched a collective industry response called “the case for action” which can be viewed here .  Our views seem to align with the collective industry response in most places, which is encouraging.  We hope that the UK-GBC’s task group report is fully considered and taken on-board by the Government.

1. Part L
The recent part L update brings a 9% reduction, as opposed to the proposed 20% at consultation stage. The figure is not very ambitious; surely not enough to drive significant innovation, but it does provide a little short-term certainty to the industry. The introduction of the fabric standard (FEES) for housing is a positive measure but why wasn’t this also integrated into non-dom? On the one hand, there are obvious benefits in promoting efficient fabric design and the integration of passive design strategies. On the other, too much of a focus on fabric standards draws attention away from non-space conditioning energy loads which are arguably a significantly larger proportion of the energy mix in non-domestic buildings.

Irrespective of whether FEES are integrated into the Part L2A methodology, we believe there is a significant amount of work to be done on compliance tools.  Although both SBEM and SAP methodologies are strictly compliance tools, it is inevitable that some designers will use them to influence their designs.  The temptation to do so is further increased by BREEAM, CfSH and the GLA using compliance tools as the methodology to meet CO2 targets that go beyond Part L.  In light of these issues, the part L assessment methodology should be robust enough in case it is used for design purposes and therefore requires significant improvement in both its own capabilities and that of the quality assurance mechanisms of consultants who use it.  Although the UK-GBC response agrees that changes to SBEM are necessary, the modifications are unlikely to be as extensive as we would suggest.

Developing a more detailed dynamic simulation route (DSM) could be an interesting approach, particularly if there is a necessity to calibrate the model to metered data in operation.  This methodology is currently carried out for buildings undergoing LEED certification.  With the UK construction industry moving towards greater integration of technology into the design process via BIM, the potential to integrate ‘As built’ DSM models into areas such as facilities management is becoming a reality. If encouraged via building regulations, it could make significant in-roads into the performance gap. We believe that this is the way forward particularly for larger projects but would the industry be willing to take this step? How much difference would it actually make, and at what cost to the client?

2. DEC
Display Energy Certificates are an underutilised element in the context of energy regulation of the built environment. Their adoption has certainly represented a step-change in terms of making more information available on actual energy consumption in public buildings. A lot has been said about the fact that the methodology has its imperfections and is not applied consistently across the industry. Nevertheless, we feel that this instrument needs to be enforced more strictly, along with part L and EPCs, and with better quality assurance. Making DECs mandatory for all non-domestic buildings is a positive and relatively simple step to heightening the awareness of energy and CO2 amongst building owners and users.  We are starting to find clients that are targeting DEC levels at the design stage.  This is already filtering down to contractors and in particular to BAM, who we are working with to assess how these targets can be met.  In-use targets at the design stage, is a refreshing approach that, as designers and energy consultants, we have pushed through our work and through CarbonBuzz, and that so far seems to be fostering improved integration amongst the design disciplines and between pre- and post-construction performance.

3. Energy: Regulated/Unregulated/Embodied
A large proportion of the questions in the consultation focused on whether the different types of energy use should be part of the zero carbon definition. Should lifts, escalators and over-door heaters be included in the definition of building services? Our view and that of the UK-GBC response is yes. From industry experience we have seen that more energy efficient lifts and escalator systems are already being implemented in commercial settings, as the cost of including these are minimal compared to other un-regulated energy uses. To date this has mostly been driven by BREEAM credits for lifts and elevators and local councils mandating BREEAM targets on most new build non-domestic buildings. Care must be taken in the calculation methodology, though. Over-door heaters for example can be easily designed out of buildings via draft lobbies or revolving doors. There must therefore be an advantage within the model from designing them out of a building services model.

What about unregulated loads? It would be advisable if these could be included in the zero carbon definition since they represent a large proportion of a building’s operational CO2.  However, this should be implemented in a way that encourages building users and energy managers to actively optimise unregulated loads since there is a limit to the influence that designers can have.

As for embodied energy, its inclusion in the definition post-2019 sounds like a good effort towards addressing the whole life CO2 impact of the built environment. The methodology needs to be carefully thought through in a way that it does not push key factors such as aesthetics, thermal comfort and indoor air quality out of the design equation.

4. Allowable Solutions
Still in its early stages of development and yet to be confirmed for new non-domestic buildings, it looks like this scheme will experience a number of changes before full implementation. An alternative method for assessing the required carbon abatement via Allowable Solutions will be needed, since adopting current compliance tools like SBEM is unlikely to lead to accurate reductions in CO2 in operation. There also needs to be a clear maximum % reduction via allowable solutions in order to ensure design efficiency is prioritised.

5. Building Performance Evaluation (BPE)
What the industry as a whole aims to achieve are nearly zero carbon buildings in-use and, pragmatically speaking, that may only be viable through investing in learning from how new buildings are performing in operation. Not to mention that monitoring the success of updates of building regs is paramount in ensuring we are on the right track.  BPE techniques should be integrated into the construction and operation process. This should be encouraged or enforced by building regulations.

That was a summary of our views on some of the big Zero Carbon issues.  What are your thoughts?  It would be good to hear about your opinions on the hot topics.


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