Healthcare Facilities Study Calls for more Accurate Data at All Stages of Building Development

By Karen Duffin on Wednesday 21 March 2018

A recent project undertaken by Health Facilities Scotland (HFS), IES Consulting and Mabbett & Associates has highlighted the importance of implementing accurate data for energy and thermal comfort design modelling from the early stages, and throughout, the building development process.

HFS, part of NHS National Services Scotland, commissioned the study after it became apparent that a number of new NHS healthcare buildings were falling short of their energy and comfort design predictions once in operation. In particular, they wanted to understand and address the issues concerning space overheating causing uncomfortable conditions for occupants and elevated cold water temperatures increasing water safety risks.

It is important to note that these issues arose despite the building design and staged modelling having demonstrated compliance with local government building regulations. So, what went wrong?

The main problem here lies with the lack of specific and accurate building data available (or used) at the design stage.

Currently, building compliance is tested against the UK government sourced National Calculation Method (NCM) data, which is also widely used for design calculations in the absence of intended operational data. However, it is widely understood NCM data is intended to be used for comparison only, not an absolute calculation, and therefore the results of any UK compliance calculation can never be regarded as a true prediction of operational energy use, nor thermal comfort conditions.

The NCM data unfortunately only takes into consideration heat gains attributed to occupied spaces including loads for people, lighting and equipment, meaning important gains from hot pipework and electrical cables in adjacent voids can be omitted from the calculations entirely. Furthermore, differences in the time schedules results in heat gains within the operational buildings that contrast significantly to NCM-based predictions at different times throughout the day or year.

IES Consulting first created separate baseline models using the NCM data to represent a typical healthcare centre and hospital ward (since each building type has different operational requirements). IES then modelled the same buildings using "improved" data gathered and provided by Mabbett & Associates from representative existing buildings, to create the Corrected Base Case (CBC) models. The CBC models provide a more accurate reflection of the operational health centre and hospital buildings, by drawing from the experience of true to life data of similar developments.

The discrepancy between the NCM and CBC data proved to be significant in many areas. In the case of hospital bedrooms, for example, the CBC demonstrated that the real world energy consumption - and associated heat gain - within the space was as much as six times higher than the NCM data assumed.  The overheating risk was found to be greater when using the improved CBC data, with results showing more than 1,000 hours of predicted overheating per year compared to 0 hours when using the NCM. Now, while the NCM may produce more favourable results at the modelling stage, the comparison here proves that the unsatisfactory operational performance of the buildings is more or less inevitable and could have been predicted from the start of design.

Current 2015 building regulations in Scotland now incorporate more stringent requirements for insulation and improved airtightness when compared with previous versions. It is therefore paramount that designers maintain an awareness of the impact these changes have on space heating requirements, which will be greatly reduced when compared to older buildings. The chance of overheating, even in cooler months, becomes more of a risk. Designers must take into account the way occupants will interact with the space during cooler months. For example, an occupant not used to high insulation standards in their place of work or home may find it unintuitive to open windows when outside temperatures are low, an issue which should be addressed during the design phase.

“This innovative report provides tools that should substantively improve future briefing of NHS Scotland new build projects, and thereby enable better more sustainable facilities and ultimately improved service outcomes for users.”

The ‘Performance Gap’ has been well documented in recent years and there is a definite push within the industry towards commissioning and ongoing performance monitoring of buildings once they are in use. This enables teams to detect and rectify some issues but what if these issues were predicted earlier during design? Often by the time the building is in use many of the design decisions made early on – and which can have the most significant impact on the building's operational performance – will be irreversible or costly to rectify.

This study highlights the need to ensure informed decisions, based on the most accurate data available, are made at every stage of the design process. This is achieved by ensuring each individual involved in the building design is well equipped to make the all-important design decisions influencing the process.

Through their analysis, IES Consulting and Mabbett & Associates presented a number of recommendations to help HFS formulate a new approach to future NHS building developments. The proposed measures included:

  • Superior design modelling procedures to be integrated across design team members.
  • More realistic model input data and identification of the measures needing consideration at each stage.
  • Identification of the project team member best capable to mitigate known risks and to provide the modelling evidence at each stage in the design process.
  • A standardised approach identifying the analysis needed alongside the required results and format to enable direct comparison across analyses.
  • Creation of a 'Knowledge Base' of design data that designers can use in their simulation modelling.
  • Improving design team capabilities by ensuring they have demonstrated the necessary modelling capabilities. This should be verified through model audits at key milestones.
  • Project mentoring customised to train each team member in the analysis of particular design aspects; shade and window selection for the Architect, plant sizing and ventilation controls for the M&E Designer.
  • An NHS Scotland design database to gather and maintain data from operational buildings and operational templates across their building types.
  • The potential revision of existing design guidelines.
  • Feedback on design decisions by gathering operational energy data from newly constructed buildings to evidence the progress of improvements.

The report also provides tools for buildings in-use, as this modelling approach can also be used to predict the effects of planned changes in operations, such as longer opening hours, on aspects of energy and thermal comfort.

Importantly, many of these measures are applicable in building sectors other than just healthcare and would help ensure performance issues are mitigated as early in the process as possible. Accurate and detailed modelling at every stage is the future for design. It's proven to lead to safer, more comfortable, energy and cost efficient, sustainable buildings.

Susan Grant, Principal Architect at Health Facilities Scotland, made the following comment: “IES and Mabbett & Associates have worked closely with NHS Health Facilities Scotland to develop this report on recent performance gaps and future modelling in two exemplar inpatient and outpatient new build projects. This innovative report provides tools that should substantively improve future briefing of NHS Scotland new build projects, and thereby enable better more sustainable facilities and ultimately improved service outcomes for users.”

Read the full project reports below.

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