Ultra-low energy building fabric
Buildings should be designed to mitigate the impact of development on climate change by aligning with standards of net zero carbon. Ultra-low energy building fabric should be used, with a view to ensuring that space heating demand for both residential and non-residential development meets Energy Use Intensity (EUI) targets:
- Residential <35 kwh/m2.yr
- Office <55 kwh/m2.yr
- Research labs <55-240 kwh/m2.yr
- Retail <80 kwh/m2.yr
- Community space (e.g. health care) <100 kwh/m2.yr
- Sports and Leisure <80 kwh/m2.yr
- School <65 kwh/m2.yr
A Key Performance Indicator (KPI) for space heating demand of <15 kWh/m2.yr, comparable to those achieved through Passivhaus, should be strived for.
Predictive energy modelling should be used, for example Passive House Planning Package (PPHP), CIBSE TM45 or equivalent, and carried out with the intention of meeting the target EUIs. This should be completed as part of any detailed planning submission, reconfirmed pre-commencement, validated pre-occupation and monitored post-completion.
Thermal comfort and overheating
With improved building-fabric performance comes the need to ensure appropriate levels of thermal comfort in order to avoid the risk of overheating.
Thermal comfort and the risk of overheating should be given full consideration in the earliest stages of design to ensure passive measures are prioritised over the use of more energy-intensive alternatives such as mechanical cooling. Overheating should be mitigated through appropriate orientation, massing and good design.
A modelling sample proportionate to development density can demonstrate full compliance with CIBSE TM59 for residential and TM52 for non-residential development, addressing overheating in units considered at highest-risk. Overheating calculations should be carried out as part of the detailed planning submission and reconfirmed pre-commencement.
Fossil fuel free
Developments are expected to be fossil-fuel free to avoid any new reliance on fuels such as oil and natural gas, for space heating, hot water and cooking.
All developments should therefore incorporate electricity fed systems.
Zero operational carbon balance
The amount of energy required by buildings on-site should be balanced by installing on-site renewables, for example through Solar PV, to supply the equivalent amount of energy.
The quantum of proposed renewable energy should be shown in kWh/yr. The amount of renewable energy should equal or exceed the total energy demand for the development in order to achieve net zero operational carbon as a whole.
Buildings designed to be net zero operational carbon should also perform to this standard when complete. This is to minimise the risk of a performance gap, when the as-built design does not perform to the standards of the original, designed performance submitted at planning stage. Post-occupancy energy monitoring should be carried out to verify the energy consumption of the development in-use.
Embodied carbon emissions
Embodied carbon is the CO2 emitted in producing raw materials and products, including, for example, building materials and products associated with mechanical and electrical engineering.
Upfront embodied carbon emissions include the product, transport and construction stages. Developers should strive for upfront embodied carbon emissions for residential and non-residential buildings of < 500 kg CO2/m2. Calculations of the expected upfront embodied carbon of buildings should be provided. Full life cycling modelling is encouraged.
The use of environmentally sustainable materials with low embodied carbon should be used, for example reused, reclaimed or natural materials that are durable. A lean design, in terms of structure, architecture and building services, will minimise the use of materials.
It is important to allow for flexibility and consider how the layout may be adapted to suit future needs. Maintenance and access requirements should be considered to ensure equipment lasts longer, as should the reuse of buildings at the end of their life.