CARBON AND ENERGY REDUCTION
carbon based on LETI (London Energy Transformation Initiative) guidance. These targets come from ‘business-as- usual’ benchmarks for other non- domestic buildings typologies, such as offices, that are not representative of healthcare buildings’ energy and carbon footprint. We believe that accurate energy benchmarks, full building energy modelling information, credible whole lifecycle analysis, and availability of reliable data from the building industry, are key to bridge the ‘performance gap’ between designed energy uses versus actual/metered energy data for hospital buildings. We know that no two hospitals are the same, and that a clear understanding of the hospital typology is important to be able to establish a benchmark energy use for the hospital. Working towards this goal, NBBJ and Hoare Lea are collaborating to collate metered annual energy use data benchmarks from existing NHS hospital buildings, through Display Energy Certificates, that are more reliable for measuring our designed improvements against the 2030 challenge targets.
Leading the dialogue at early RIBA design stages
Design team leaders – usually architects – must lead the dialogue at early RIBA design stages with the hospital Trust, local city councils, energy providers, and other stakeholders, to clearly define realistic and achievable targets for operational energy, embodied carbon, and on-site renewable energy generation. In the long term, savings achieved through better hospital design will provide long-term value, with the lowest environmental impact possible, through
The Dumfries and Galloway Royal Infirmary.
significant year-on-year energy savings for the NHS estate in the operational phases, and reduced carbon offset costs to reach net zero carbon design. The best way to establish an energy benchmark for a hospital is to study the actual metered energy use data reported in the annual Display Energy Certificates (DEC) of other similar operational hospitals, to help us to learn lessons on how to improve building energy efficiency.
For example, our research into hospital energy benchmarks revealed that the Dumfries and Galloway Royal Infirmary had an actual annual energy footprint of 422 kWh/m2
in area, and nearly 45% more energy-efficient than the highest DEC data of existing older hospital estates, such as the Royal Free London Hospital.
hospital was 20% more energy-efficient when compared with the average DEC annual energy data from 2019 for 20 other similar UK hospitals greater than 50,000 m2
that was 20% more than the
as-designed Building Regulations figure. This showed a performance gap between as-built and as-designed. However, the
Percentage of areas with more than 300 lux of daylighting on a hospital floor plate Middle floor
47% 4280 m2
Middle floor
37% 7440 m2
2: Optimise and reduce Careful analysis of the specific environmental and climate context of the hospital site can reveal the greatest potential in harnessing the benefits of passive design, that in turn achieves the biggest savings in energy and carbon. At early concept stages, the design team can determine climate-sensitive design drivers by studying the weather data, site microclimate, solar orientation, and wind direction, as well as potential to enhance the on-site ecological patterns and green spaces. A nature-based design approach can help to identify those months of the year where the building envelope can achieve healthy human comfort conditions through passive measures, and will reduce the number of days where environmental conditions may go above acceptable limits for patient and staff needs – for which a limited amount of additional energy will be needed to achieve a balanced indoor environment.
Digital tools Top floor
68% 2400 m2
Daylight analysis of a typical hospital floorplate. 66 Health Estate Journal September 2021 Top floor
60% 2220 m2
Digital tools such as BIM 360, CoveTool, Rhino/Grasshopper, and Sefaira, enable us to quantify the impact of local climate on building form-making, to take early design decisions based on rapid parametric environmental studies to test early concept ideas for the best possible hospital building design. This helps us to quickly compare different options to analyse which design is best at harnessing daylight, fresh air, nature, and views to support health and wellness, while
©Hoare Lea
©Paul McMullin
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