The proposed policy approach for net zero carbon from new buildings is innovative and challenging relative to energy targets. The University supports the overall approach given its own science-based target to deliver a zero carbon estate, but we note that in some cases the proposed standards are so tight that they require a more nuanced approach with slight relaxations where there is a reasonable justification, as follows:

A space heating demand of 15-20 kwh/m2/p.a for domestic and non-domestic buildings

This is very close to Passivhaus Standard. This in effect mandates triple glazing, mechanical ventilation with heat recovery, and the highest standards of insulation and air-tightness. We recommend allowing a relaxation where site constraints mean solar access is poor or an optimal form factor cannot be achieved.

Total energy use intensity (EUI) of 35 kwh/m2 for residential

This EUI goes beyond the exemplary ‘Passivhaus’ standard. We ask that an illustrative energy budget based on a real example be provided to show how this is achievable in practice.
We recommend allowing a relaxation where site constraints mean solar access is poor or an optimal form factor cannot be achieved.
Use of EUI could unfairly penalise smaller dwellings. For example, someone using a fridge and a cooker in a dwelling of 50m2 uses double the kWh/m2 for those appliances as the same person in a dwelling of 100m2; there is no dsign solution for that. We recommend a space efficiency factor be applied.

150kwh/m2 for research space

Actual EUI will be highly variable depending on the nature of the research. The University’s Civil Engineering Building was predicted to consume 80kWh/m2/yr and is achieving 77kWh/m2/yr. The Heart & Lung Research Institute, however, is predicted at 245kwh/m2/yr as it will have to provide high rates of ventilation and contains energy intensive equipment.

We suggest ‘process energy’ such as autoclaves, ultra-low temperature equipment, fume extraction etc. fall outside the research space EUI standard. Efficiency relating to this type of non-standard consumption can be demonstrated through the BREEAM ENE07 credit for ‘Energy efficient laboratory systems’.

100% renewable energy provision, preferably on-plot

Efficient PV could deliver 120kWh/yr per m2 of panel. In effect, this means roof mounted PV will struggle to meet demand where two storeys each have an EUI of 55kWh/m2/yr, even if 100% of the roof is covered in PV and there is no shadowing. This means significant renewable energy will have to be sourced elsewhere on-site or off-site for buildings above two storeys.

This policy proposal implies any non-domestic building of more than one storey will require 100% of the roof to be covered in PV (unless we see significant increases in PV efficiencies). We recommend that clarification be given that this policy should not be at the expense of equally environmentally beneficial proposals such as roof mounted air source heat pumps, roof level amenity space, and ‘green roofs’.

Policy should clarify that where peak PV output is likely to exceed building demand, and the local Distribution System Operator has insufficient capacity to receive the excess, then the offsetting route will be acceptable.
As grid carbon factor drops, it is possible that the carbon emitted to manufacture and install a PV array and associated infrastructure will exceed the lifetime carbon savings. This should be recognised in Policy for future proofing.

Offsetting only to be used in specific circumstances (e.g. insufficient roof space) with such buildings future proofed to enable 100 zero carbon through upgrades

Policy should clarify the accountancy requirements for this policy. For example that a Power Purchase Agreement for 100% renewable electricity will be accepted. Also, that If the applicant makes an advance investment in offsite renewable energy, this will be regarded as an offset ‘bank’ for future construction projects.

General comments

Confirmation is sought as to whether the proposed policy would apply to major refurbishment as well as new build
The proposed Energy Use Intensity figures are defined in kWh/m2. Confirmation is sought as to whether m2 is defined as gross internal floor area, and is kWh is defined as metered energy.
An exception to EUI standards should be allowable where building usage will be exceptionally efficient in use of space e.g. hot desking to maximise occupancy, or extended opening hours.
A definition of how EUI will be predicted is sought – in practice will the ‘most likely’ scenario in the range of outcomes defined in a CIBSE ‘TM54’ Operational Energy Evaluation carried out by a competent professional be accepted?
EUI does not take into account the desirability of storage to relieve pressure on the grid, minimising need to switch on high carbon electricity generators. Storage in the form of batteries, thermal stores and inter-seasonal storage in the ground should be encouraged. Confirmation is sought that higher EUIs associated with energy storage will be accepted where this brings a net saving in grid carbon.
We welcome the requirement to measure embodied carbon for large projects as this is in line with existing University Design Standards. We note there is a big disparity between the threshold sizes for non-residential and residential development and suggest these be treated more equally.