Performance gap between building design and operation
There is significant evidence to suggest that buildings do not perform as well when they are completed as was anticipated when they were being designed. The difference between anticipated and actual performance is known as the performance gap.
Findings from studies such as PROBE (Post Occupancy Review of Buildings and their Engineering) which assessed 23 buildings previously featured as ‘exemplar designs’ in the Building Services Journal between 1995 and 2002, revealed that actual energy consumption in buildings is often twice as much as predicted.
More recent studies have suggested that in-use energy consumption can 5 to 10 times higher than compliance calculations carried out during the design stage:
- The Zero Carbon Hub Closing the gap between design and as-built performance, Evidence review report.
- Innovate UK's Building Performance Evaluation Programme.
- The Carbon Trust‘s Closing the gap, Lessons learned on realising the potential of low carbon building design.
- Carbon Buzz, Performance gap benchmarking data.
Studies such as these suggest that factors contributing to the performance gap include:
- A lack of monitoring and feedback following occupancy, meaning that problems are rarely identified, user behaviour is not corrected and lessons are not learned for future projects.
- Design assumptions do not properly reflect the in-use performance of buildings.
- Designers are rarely required to predict actual in-use energy consumption.
- Calculations for regulatory compliance do not account for all energy uses in buildings. These calculations are commonly misinterpreted as predictions of in-use energy consumption, when in fact they are simply mechanisms for complying with the Building Regulations.
- Unregulated sources of energy consumption such as small power loads, server rooms, external lighting, and so on are rarely considered at the design stage. Yet these typically account for more than 30% of the energy consumption in office buildings.
- The lack of guidance for modelling unregulated energy loads makes it difficult for designers to consider these at design stage.
- There are discrepancies between design specification and the specification and quality of works as-built.
- There are incorrect assumptions about the performance of some building components (such as party walls).
- There are rarely any consequences for designers, contractors and suppliers when energy consumption exceeds predictions.
- Project participants struggle to communicate the intended energy performance for the design from the earliest stages, and have ongoing problems with communicating the design intent throughout detailed design.
- There is poor feedback from site about what is, and what is not buildable.
- Site practices that may have been acceptable 20 years ago, no longer meet the required standards.
- There is an absence of engineering rigour around the design and installation of the services.
NB: In November 2015, BSRIA announced that it would back a four-month feasibility study to develop a prototype UK scheme intended to deliver the standard of energy performance specified in client briefs by adopting a ‘design for performance’ approach, first pioneered in Australia. See BSRIA support study into Australian solution to performance gap for more information.
[edit] Related articles on Designing Buildings
- Achieving sustainable futures with thermal imaging.
- Building data exchange.
- Building performance.
- Building performance evaluation programme.
- Building performance metrics.
- Building regulations.
- BREEAM.
- Closing the gap between design and as-built performance.
- Co-heating test.
- Code for sustainable homes.
- Domestic ventilation systems performance.
- Energy performance certificate.
- Energy Savings Opportunity Scheme.
- Facilities management audit FMA.
- Green building.
- Leadership in Energy and Environmental Design.
- Mind the (performance) gap.
- Performance.
- Performance of exemplar buildings in use: Bridging the performance gap FB 78.
- Performance requirements.
- Quad Central in Malta aims for LEED Platinum certification.
- Retrofit, refurbishment and the growth of connected HVAC technology.
- Soft landings.
- Strategic performance targets.
- The effects of subframe systems on the overall thermal performance of external rainscreen walls.
- The history of non-domestic air tightness testing.
- Thermal imaging to improve energy efficiency in building design.
- Why the UK needs to support emerging tech like energy storage.
Featured articles and news
Designing sustainability and performance into buildings
Specifying and selecting sustainable resilient timber products.
Modifying wood to improve resistance to decay and movement.
A last minute, long look for built environment professionals.
The architecture of creative reuse. Book review.
Installing solar panels on listed structures.
Sustainable development global goals, history in progress?
"Unless we act now, the 2030 Agenda will become an epitaph for a world that might have been."
Mike Kagioglou FCIOB named CIOB President
'Sustainable Development Goals must be focus for construction'
BSRIA training; a look at what's on offer
From energy management to compliance training.
TESP video warns to beware of rogue trainers.
Highlighting the slippery tactics of non-approved providers.
New Building Safety Wiki launched
Boosting awareness and understanding of the new fire safety regime.
New playbook on AI in construction published by CIOB
How to get to grips with, and the best from AI.
Digital Construction Report NBS
BIM, cloud, off-site, immersive tech, AI, twins and sustainability.
ECA learning zone and industry focus video series
From updates and amendments to circular economy, emergency lighting and much more.
The Building People Communities Network
Celebrating and amplifying voices of the under-represented, this refugee week and pride month.
Pride of Place: queer heritage
Acknowledging and taking pride in LGBTQ histories.
Comments
Brilliant article. We made a document that really simply covers what Ventilation refurbishment actually is and why it can be beneficial as opposed to a replacement. Don't feel any pressure, but have a look if you want a really simple updated definition. Click here
https://www.bvs-ltd.co.uk/2023/06/07/refurbish-or-replace-making-the-right-choice-for-your-ahu-unit/