Energy efficiency: building technology
The best of intentions
1 March 2019
Low- and zero-carbon building technologies must operate correctly to achieve the best assessment ratings, maintain Helena Bradford and Marc Hill
The sustainability and energy performance of buildings are calculated, assessed, rated and certified using the Building Research Establishment Environmental Assessment Method (BREEAM) and energy performance certificates (EPCs), among other approaches.
The 2010 Energy Performance of Buildings Directive and the 2012 Energy Efficiency Directive are the EU’s main legislative instruments in this regard. The overarching requirements are for member states to implement a methodology for calculating buildings’ energy performance, setting out minimum requirements and implementing EPCs. In the UK, an EPC is required when a building is constructed, sold or rented.
The use of EPCs should allow those involved in the acquisition of commercial property to assess how energy-efficient it is, and enable them to make informed decisions with respect to saving energy and reducing costs. The EPC’s rating should also assure them how well the building has been designed and the levels of comfort and well-being that its occupants can anticipate, as well as helping fight fuel poverty by reducing energy demand.
Although EPC ratings are based on compliance being proved by design, there is no direct relationship with actual building performance. Nevertheless, the certificates have helped improve understanding of current UK building stock and encouraged developers and portfolio owners to improve the energy efficiency of their buildings. Investors and occupiers are now setting their own sustainability targets by establishing minimum EPC ratings for new-build properties, new acquisitions and refurbishment works.
Current planning requirements encourage good EPC ratings by setting BREEAM and carbon-reduction targets as well as minimum requirements for low- to zero-carbon technologies (LZCTs). Depending on the size and the nature of a development, councils can require a specified BREEAM rating, and impose a percentage reduction in carbon emissions through the use of LZCTs.
BREEAM is designed to help measure and reduce environmental impacts and create more marketable assets. To provide a flexible approach to the assessment and rating of building performance, most BREEAM credits can be traded and non-compliance in 1 area can be offset by compliance in another. Minimum standards are, however, set in key areas such as energy, water and waste, to ensure performance against fundamental criteria is not overlooked.
The design and selection of the building services installations as well as the building fabric are key in ensuring energy performance
As these minimum standards largely relate to energy use, the design and selection of the building services installations as well as the building fabric are critical in ensuring that a building meets the required performance targets. The heating, cooling and domestic hot water plant and building fabric will have minimum requirements, for which evidence will be gathered to model the building’s energy performance using accredited software. The aim is to ensure that the building is compliant on completion, and this will need to be witnessed by the assessor to lodge an as-built EPC.
If post-construction considerations such as handover, commissioning, training and routine servicing are not effectively implemented, this can result in the operational status and efficiency of the building services and LZCTs not being maintained and the calculated building performance not being achieved. It can also lead to increased operational, maintenance and energy costs and a reduction in occupant satisfaction, comfort and well-being.
There are a number of frameworks, rating systems and documents that identify and encourage appropriate handover, commissioning, building aftercare and maintenance principles, along with guidance on assessing the performance of occupied buildings and improving efficiency. These include the Aftercare guide: Developing efficient buildings for any occupier, a report produced by the British Property Foundation and researched by Tuffin Ferraby Taylor.
Although the assessment methods are well established and there is a wealth of guidance for the occupancy stage, there are numerous case studies demonstrating that best practice is not consistently implemented by those who own and operate buildings.
Over many years of providing technical due diligence, dilapidations, building condition, maintenance and sustainability advice for clients involved in the acquisition, occupation and disposal of commercial property, Tuffin Ferraby Taylor’s building services engineers and sustainability consultants have identified a number of instances of such failings.
One example is a 10-year-old landmark regional headquarters building of around 16,250m2 that has a BREEAM rating of ‘excellent’ and an EPC rating of C. The building services installations include a solar domestic water heating system, comprising heat collectors and associated storage vessels, pumps and controls. The design intent is for this system to provide pre-heated water to storage calorifiers.
However, site investigations determined that the solar hot water system was not operational. A review of the documentation and discussions with the site-based incumbent maintenance contractor’s engineers identified that there were no records in the operation and maintenance manual to confirm design or operating strategy, or that commissioning had been undertaken.
The feedback from the engineering team was that the system had not been operational since installation, and this had not been addressed as part of the de-snagging process during the rectification period. In addition, the engineers did not fully understand how the solar hot water system operated in conjunction with the domestic hot water calorifiers, and since the equipment had not been included in the planned preventative maintenance contract it had never been subject to routine servicing.
A 2nd case study relates to a 20-storey landmark office building of around 20,900m2 in size, completed in 2014 to a high-quality specification. The building has a BREEAM rating of ‘excellent’ and an EPC rating of B.
During the site inspection it was identified that there were a number of defects and outstanding repairs associated with the services installations. Some of these defects concerned the base build construction, which had not been dealt with when it came to de-snagging in the rectification period. Furthermore, while the building services incorporated a system of solar photovoltaic modules and associated inverter, generation meter and isolator, this system was isolated and not operational.
In each of these 2 case studies, the freehold interest was being purchased for investment purposes, and the BREEAM and EPC ratings were likely to be reflected in the property valuation. The non-operational LZCT systems did not satisfy BREEAM assessment criteria. The poor condition, legacy maintenance and repair issues and decrease in system efficiency thanks to the faulty services installations were not reflected in the respective EPC ratings.
These installations would therefore require substantial rectification works to fulfil the EPC and BREEAM ratings. Each property also had a large number of defects and items of disrepair, such as poor-quality closed-water systems, while the heating, comfort cooling and building and energy management systems were not functioning correctly.
The correct design and operation of building services and LZCTs has many advantages. These include achieving desired assessment ratings; reducing energy bills, carbon footprints and greenhouse gas emissions; improving energy system sustainability; and decreasing reliance on external suppliers of fossil fuels.
In buildings where LZCTs are not operating as per their design intent, the EPC rating would most likely worsen if the property were reassessed. In addition, the number of BREEAM credits required to achieve the certified performance rating would not be achieved, and there will also be a likely drop-off in the predicted carbon reduction and associated benefits. Calculated payback periods will not be realised either.
Assessment methods are well established. Although only BREEAM’s ‘outstanding’ rating requires consideration of a building’s occupational performance, guidance on best practice for operational buildings is extensive.
Sustainability is an ongoing obligation that requires long-term consideration and investment; experience of operational buildings has identified that, in many instances, the design intent and performance of LZCTs and services installations are not being achieved. This must be addressed by designers, installers, owners and occupiers, and there must be a shift from achieving compliance by design to fulfilling performance in occupation.
Once ratings have been calculated, servicing and operating conditions must be considered to ensure the basis of an assessment is maintained. Major improvement is required in many buildings if actual performance is to reflect current BREEAM and EPC ratings.
Buildings must be operated and managed with a focus on what is needed to achieve the design intent. In addition, if building owners and occupiers are paying a premium based on assessment ratings, robust technical advice should be sought as operational status may not reflect assessment ratings and the building may not be providing the expected energy and sustainability benefits.
Helena Bradford is a senior energy and sustainability consultant and Marc Hill is a technical partner at Tuffin Ferraby Taylor