CONSTRUCTION Scope 1
Building direct burned fuel (gas, oil, LPG, biomass etc)
Owned fleet fuel (petrol, diesel)
Anaesthetic gases
F-gases
Owned fleet (electric)
Scope 2
Building electricity
Building purchased
heat and steam Scope 3 Water consumption
Waste water treatment
Waste arisings Business travel
Staff commuting Patient travel Supply chain
Figure 1: The three ‘Scopes’ of emissions, as defined by the Greenhouse Gas Protocol.
commissioned artworks throughout the Hub. Art will be unique to the local area, developed in collaboration with local community groups.
Engineering story The site occupies an area of approximately 2 hectares, characterised by sloping ground from south to north, with a 4.5 m level difference between the south-east and north-west corners. The levels strategy has been informed by the overall proposals, recognising flood risk, drainage, earthworks, and site access. Several building options were investigated, including split-level and partial basement construction. The proposed building structure comprises three primary building blocks – a four-storey block, a three-storey block, and a single-storey plant block linking the two larger blocks. Options for the structural frame were explored early in the design process and evaluated against end-user aspirations, architectural intent, buildability, future alterations, integration with services, and budgetary considerations. The final design adopts a braced steel frame, with roof and floor plates formed in composite concrete / metal deck slabs on downstand beams. There was a desire to minimise columns in Level 3, so the roof over this space incorporates long span beams to maximise column-free spaces below.
Proposed structural frame The proposed structural frame is a simple braced beam and column frame, with lateral loads being transferred through the floor and roof plates into vertical bracing, and then down into the foundations. The ground is poor, with weak silts and clays present to significant depth. Traditional shallow foundations will not accommodate the potential load scenarios estimated, and piling is required to support structural loadings. The design adopts pre-cast
36 Health Estate Journal September 2022
concrete piles driven to refusal into the weathered rock horizons below the superficial deposits. Concern over long- term consolidation settlements under the ground slab led to it being designed to act as a suspended reinforced concrete slab supported on ground beams that are supported on pile caps.
How the Hub will achieve Net Zero NHS Greater Glasgow and Clyde as a board is committed to achieving ‘Net Zero’ by 2045. As part of the Hub project, the design team was set a challenge around providing a low carbon design based on the following requirements: n NHS Greater Glasgow & Clyde ACRs (Authority Construction Requirements).
n Glasgow City Development Plan – Achieving Section 7 Gold Standard, equivalent to a 38% Building Emissions reduction on the Target Emissions Rating (TER), calculated using the Scotland Building Standards Section 6 National Calculation Method (NCM) modelling.
n BREEAM ‘Good’, with aspirations to achieve energy credits relating to low carbon, and passive design. In relation to improving the project’s
emissions, these can be considered in three ‘Scopes’, as defined by the Greenhouse Gas Protocol (see Figure 1). A primary focus of the design was on ‘Scope 1’ emissions, defined as ‘All Direct Emissions from the activities of an organisation or under their control, including fuel combustion on site such as gas boilers, fleet vehicles, and air-conditioning leaks’. Scope 2 emissions were also considered during the Hub Stage 2 design process, via TM54 energy modelling. The project team reviewed what
would be achievable at ‘day one’ of the project, taking cognisance of cost, risk, and available technologies. While the building will not achieve ‘Net Zero’ on opening, there is a roadmap to achieving
this in future, primarily focused on the decarbonisation of the electrical grid, fast becoming reality when viewed with Scottish actual Carbon Intensity figures. However, there are other factors that will be reviewed post-occupancy to improve the performance of the facility.
Approach to design – RIBA Stage 0/1 concepts From project conceptualisation, there was a key focus on low and zero carbon design, as well as closing the performance gap between ‘target’ energy use figures and ‘real world’ energy usage. Essentially this stage focused on the ‘Scope 1’ emissions. It was identified early on that traditional engineering approaches, particularly in relation to energy modelling, are based on outdated values and standards not necessarily representative of a health and social care centre, and that a holistic approach to sustainable design was required to achieve real-world carbon savings. Approaching the design thus, it was clear that effective benchmarking would be required. The team worked closely to produce benchmark carbon targets based on other health centre facilities as part of the Pre-Stage 1 Energy Strategy and Approach Report. To ensure that real-world carbon savings are realised, the design team approached the project with an Energy Hierarchy Strategy, first focusing on improvement to fabric, to provide ‘passive’ energy savings, then looking at minimising building services, and incorporating high- efficiency, low-energy systems. The final step was to consider on-site low and zero- carbon technologies.
Efficient building fabric design At RIBA 0/1 stage, discussions were held around efficient building fabric design, including low U and G Values building elements, low air permeability, and solar shading devices. Discussions further considered the feasibility of concrete frame construction, which could provide thermal mass benefits and improve building airtightness; however, a steel structure was agreed upon due to numerous supply chain risks associated with concrete. These early stage reviews effectively formed a ‘shopping list’, with subsequent cost checks undertaken, and full risk workshops held, to determine how they could impact on the project moving forward. This allowed NHS GGC to make informed decisions based upon cost, risk, and reliability. To minimise mechanical systems in the building, Dynamic Simulation Modelling and Bulk Airflow Analysis were carried out on the building form to understand its capacity for adaptive comfort through natural ventilation over traditional comfort cooling systems. The results showed it could effectively mitigate summertime overheating using this system. Where
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