SUSTAINABILITY
be all those things, and every major project should seek to improve on the last project. Setting an unachievable target, however, does tend to discourage, and can lead to the target being disregarded. Early research is important. What have similar projects elsewhere achieved, and how have they done it? Most successful
energy etc. This would be a typical zero carbon target.
n Set an operational target where all the ‘plug-in’ and process loads can be met additionally by on- or near- site generation.
Figure 2: BREEAM Whole Life Carbon Indicators.
project teams are keen to share their experiences, and a visit to a similar facility is often worthwhile, both from a clinical and a design perspective. A team will have confidence in a target if it has been shown to be possible elsewhere. What have been the successes and less successful outcomes of projects within our organisation? It is surprising how little thorough Post-Occupancy Evaluation is undertaken, even though it is part of many BREEAM assessments, and intrinsic to BSRIA’s Soft Landings framework. Post-Occupancy Evaluation should include evaluation of the energy and water used in a facility, compared with what was predicted at design stage. There should be an evaluation of the design and procurement process, and an honest view taken – without any blame or recrimination – on what went well and what could have been better, from both the project team and the user’s point of view. Ideally, high-level data on embodied carbon would be useful.
What next?
Now that we have established some benchmarks for our targets, it is worth thinking about how to set them and administer them. Ideally, the targets should be simple enough to be reported at executive level. Inevitably, there will be layers of complexity under the headline, but if the headline is clear, it stands a much better chance of being reported. The target should have the same prominence and status as budget and programme, and be reported at the same level. The targets should be measurable throughout the process.
For example, an operational energy target could be set. This could be expressed as kWh/m2
, or as a Display
Energy Certificate (DEC) rating for public access buildings. Other metrics could be used, for example kWh/unit of production. Whatever is chosen, it should reflect the actual energy used in the facility, i.e. what goes through the meter once the building is in operation. We need to think about how this would be monitored through the design process, and this is where our detail comes in. CIBSE TM54 has guidance on predicting operational energy, and BREEAM New Construction 2018 has processes for predicting it as well, in Credit Ene 01. The ultimate measurement to check the
18 Health Estate Journal July 2021
predictions is the energy and water bills during occupation.
Design energy targets are also useful, and these are measured though modelling of the building. Again, these should be calibrated against past performance. Models are normalised for hours of operation, occupancy, and average weather. They exclude unregulated energy, which is the ‘plug-in’ and process energy used in a building. It is common for a design energy model to underestimate actual performance. This is known as the ‘performance gap’, which is why operational energy targets need to be in place, but design energy targets have a useful part to play in monitoring the design. They are particularly powerful in the early stages to test concept designs.
Setting an embodied energy target An embodied energy target can be set. At present, there are few benchmarks, but as BREEAM 2018 New Construction now includes Life Cycle Analysis of the major elements of a building, it is expected that more data and benchmarks will emerge. At present, BREEAM has benchmarks for offices, retail, and industrial buildings. In any case, it is worthwhile undertaking option appraisal to compare the embodied carbon of different design decisions. Environmental Product Declarations (EPDs) can lower the predicted embodied carbon by enabling the inclusion of real, rather than industry average, carbon impact of products. A further target, which has carbon components, is a sustainability rating. BREEAM has a carbon metric within the rating which measures whole life carbon. It measures by calculating the percentage of maximum available score for the theme withing the rating. It is therefore possible to set a BREEAM rating of say ‘Excellent’, with a minimum Whole Life Carbon Indicator rating of 3 or 4.
Net zero
Net zero is a natural progression from the targets discussed above. If we aspire to true net zero for a construction project we will need to:- n Set a design target where all the regulated energy (heating, lighting, ventilation, hot water, and ancillary power) is of minimal demand, and met by renewable sources, typically PV, solar thermal, heat pumps, and waste heat
Figure 3: A large A+++ fridge will take more resources to manufacture and use much more energy than a small A+++ one. Susan Logan says: ‘If the small one will fulfil our brief, then clearly it is much better to purchase the small one. Likewise with buildings, and this is where targets can be misleading, as the metric is energy/m2
.’
n Minimise the embodied carbon through the use of renewable materials such as timber, and use of products
which have a low embodied carbon, and low construction and transport impact. n Offset by purchase any residual carbon.
The potential for offset is not an easy topic for public finance, and therefore if this cannot be accommodated within spending rules, it can be better to set a target which may not be net zero, but is the nearest to it without offsetting. Net zero at organisational level is, of course, very different, and beyond the scope of
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