Over the past six months there has been a plethora of Government announcements, White Papers and positioning papers about energy use and carbon emissions within the non-domestic built environment. There is a need for a drastic change to meet the regulatory challenge in 2050, with Carbon Budgets not expected to be met in the near future. Critical to this will be closing the energy performance gap – the difference between the intended energy use of a building and its actual, which can be up to 9 times higher. This article looks into more detail about the various announcements and more specifically in the short term how the energy performance gap can be met.
Decarbonisation Policy Efforts
Decarbonisation of electricity has been a success story for the UK over the past decade and continues with programmes towards electric vehicles, continued wind farm deployment and nuclear to further the trajectory. The Ten Point Plan and Energy White Paper both cover the approaches to be taken, but also turn towards a more thorny issue – the decarbonisation of heat. Whilst heat pumps and hydrogen have been looked at as broad areas, a policy and timelines are missing to turn the ambition into action. The Committee on Climate Change provides further input with a need to reduce losses, provide more efficient ways of delivery but also to focus upon behaviours as an increasing factor determining carbon reduction.
The Future Buildings Standard, currently out for consultation, delves further into both domestic and non domestic buildings. Within FBS, the consultation describes general trends, but not the details of a plan or strategy over the next decade to achieve the 6th carbon budget. Provision of a percentage emissions reduction target is proposed and necessary, but should reflect an absolute reduction of energy intensity - a shift from relative (improvement over notional building) to absolute targets (EUI) is needed to ensure a real change.
Recognition of the energy performance of buildings has also been made and the gap that exists between the predicted and actual energy consumption of the building. Whilst the subject has been in discussion for over 40 years, it has rarely been part of Government policy as it looks towards the operational sphere of built assets.
Future Buildings Standard
The Standard has suggested mandating energy forecasting calculations would be required and handed over for buildings over 1000m2 and changes to minimum standards for sub metering. Whilst this is an initial step, it doesn’t go far enough to resolve the known issues of the gap in energy performance of buildings.
To improve operational performance, we need more accurate operational modelling during design stages, more rigour during construction, and detailed attention on commissioning and handover together with improved client engagement throughout. In occupancy, Building Performance Evaluation (BPE) can help compare against predictions with disclosure through DECs to provide transparency.
- Effective in use modelling during design stage is not possible with the existing system (SBEM) to allow for a meaningful comparison in occupation. The use of standardised, simplified systems and internal gains settings does not allow to model the real performance of buildings and therefore to inform the design appropriately. Alternatives including PHPP, Design Builder and similar can be used.
- Mandated reporting of energy consumption, such as using DECs, will provide disclosure and transparency.
- Post-occupancy BPE is critical to highlight improvements in buildings and lessons learnt to the sector. Reporting of the results and comparison with the energy forecast will highlight where discrepancies exist and a need for investigation. Questions over level of enforcement necessary and whether thresholds for mandating the BPE or disclosure.
- Client engagement and involvement in the whole process is also critical, particularly around energy literacy – design vs. operational energy – where methodologies represent different concepts but use the same graphical language to represent outcomes. The minutiae of these are not always well understood by members of the industry and therefore this cannot be expected of clients.
The role of Building Performance Evaluations
The Government commissioned a significant piece of work culminating in 2016 with the final results of the Building Performance Evaluation (BPE) programme. This saw £8million put towards investigations of individual buildings in both the domestic and the non-domestic sectors. Funding was awarded for the performance evaluation of over 100 buildings at handover / early occupation and buildings in use no more than two years old at the time of joining the programme.
A number of specific, recurring problems were identified, all of which were picked up as part of the BPE exercise including:
- Poor commissioning of LZC technologies
- Widespread sub-metering issues; strategies are not fully thought through or correctly implemented and reconciled
- Failure of demand-controlled ventilation
- Specific fan powers higher than design targets and maximum allowable SFPs
- Gas-fired boilers running in non-condensing mode
- Back up, fossil fuel systems running as lead system
- Poor commissioning of automated lighting control
Client engagement is vital; many case studies are illustrating scenarios where aspects are paid for but not necessarily fully delivered. An engaged client is more likely to recognise this during construction, commissioning & handover and early occupation. The skills of building occupants are at odds with the complexity of the systems in new buildings; where schools have previously employed caretakers, skilled facilities managers on high salaries are needed to look after new high-tech buildings.
The studies have revealed that complexity starts early through planning and certification rating schemes. Rating schemes can sometimes push designs away from the core design strategy by drawing attention and investment towards ‘easy win’ credits. In many cases there are requirements to install specific items of kit in order to gain planning consent. The incorrect specification of technologies can often be installed as a result of funding requirements – where the funding for a certain technology can only be secured by the existence of another technology.
- Public buildings where the demonstration of CO2 reductions released financial incentives, leading to scenarios where unnecessary technologies, particularly for heat generation, led to over-complexity;
- Health centres where planning requirements specifying a certain amount of low carbon technology, resulting in an over specification of heat and overly complex interfaces with central systems.
The Committee on Climate Change highlighted that behaviours were one of the biggest contributors to energy efficiency within the built environment. Whilst this is commonly taken as temperature settings and use of lighting, it does also refer to project teams and the BPE approach to ensure appropriate designs led by an effective client.
The BPE programme found that after performing in-depth, collaborative building performance evaluations, the team’s perception of the performance of the case studies remains inflated compared to the evidence. The on-going challenge is to understand the psychology behind this.
Please note: the views expressed in this blog are those of the individual contributing member, and are not necessarily representative of the views of IEMA or any professional institutions with which IEMA is associated.
Posted on 15th March 2021
Written by Sunil Shah
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