CARBON AND ENERGY REDUCTION
sensitivities within hospital environments around infection control related to reusing water. However, innovations such as water-saving sanitary fittings, wastewater heat recovery systems, careful sustainable drainage strategies such as SUDS, blue and green roofs, and rainwater harvesting for irrigation, can contribute towards reductions in site infrastructure needs and carbon footprint. They also contribute towards climate resilience strategies and tempering local microclimate air temperatures for air intake.
Integration of Modern Methods of Construction strategies within the hospital design and construction also has significant benefits in achieving future flexibility for the hospital building through a platform approach. Besides improved quality of offsite manufacture, programme, and cost savings, this approach enables an end-of-life reuse/ recycling potential that can mitigate the initial higher embodied carbon footprint with an overall reduction when a Whole Life Cycle Carbon assessment is undertaken. NBBJ and Hoare Lea have undertaken joint research into sustainable hospital design using solar irradiance mapping and climate data digital simulations to arrive at the best building shape to maximise the potential for on-site solar PV renewable energy generation. This helped us quantify the carbon offsetting potential per unit area of the building and the site itself, before relying on other energy sources and offsetting schemes.
5: Measure and offset
At this stage, a whole lifecycle carbon analysis should be carried out for the hospital design using the RICS standard method of calculation, which considers end of life and re-use of materials based on future use and adaptation. The measured operational and embodied carbon of a building design can then be offset with carbon-free energy sources, carbon sequestration strategies, and, ultimately, buying carbon offsets from certified schemes to achieve a net sum total of zero carbon emissions. Developing the design intent around using less material finishes, where possible, without compromising the quality of internal spaces, is an easy way to achieve embodied carbon savings in the whole lifecycle calculations. Choosing the right building materials with recyclable content is also important to achieve savings in embodied carbon. For example, use of recycled aggregates, greener concrete options utilising GGBS or fly ash, reclaimed structural steel, use of FSC-certified timber, other innovative carbon-negative materials such as ‘Made of Air’ façade panels made with wood waste, and plant-based insulation materials such as cork boards, help to
Gas
Reduced capital cost High carbon offset
Limit flexibility and client control Negative air quality impact
Electric
Increased capital cost Zero/low carbon offset
Greater flexibility and client control No impact on local air quality
Hybrid
Intermediate capital cost Low carbon offset
Greater flexibility and resilience Co-benefits of circular economy
Based on the reduced carbon factors with the rapidly decarbonising UK grid energy, NBBJ and Hoare Lee say they can present different energy strategy choices to a hospital Trust and stakeholders to help arrive at the best Net Zero Carbon pathway for the particular project.
sequester carbon, and reduce the measured materials’ embodied carbon content.
‘‘
Certified sustainable materials Certified sustainable materials should be sourced from supply chains that have committed to transparent environmental product declarations, and operate a net zero carbon business that aligns with the NHS Net Zero 2040 and RIBA 2030 targets. Designers must ensure that the preferred manufacturers meet these criteria, and are clearly referenced in architectural specifications from the beginning of the design process. Any residual carbon from the whole life analysis can then be offset through a
certified carbon offset fund. At a larger district or city-wide scale, hospital estates can benefit from developing local partnerships with neighbouring developments and businesses to promote ‘net zero communities’. These can share and offset the energy consumption and energy generation during the day, depending on the occupancy patterns of different building uses. For example, on-site energy generation in residential developments can be used to power institutional buildings when people are at work, away from home, while re-use of occupancy-generated heat during work hours from offices and workplaces can be used to heat local homes through district heating networks.
NBBJ and Hoare Lea have undertaken joint research into sustainable hospital design using solar irradiance mapping and climate data digital simulations to arrive at the best building shape to maximise the potential for on-site solar PV renewable energy generation
September 2021 Health Estate Journal 69 High potential carbon offset
Zero/low potential
carbon offset
Gas carbon content 0.184 kgCO2
/kWh
Low potential carbon offset
©Hoare Lea
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