When buildings perform as designed

Until recently project teams would rarely have the opportunity to compare design intent with operational outcomes on construction projects. Gathering and assessing feedback from a product’s performance in use is essential for any designer and manufacturer yet it needed government action to kick-start this in the construction industry. Innovate UK’s £8m Building Performance Evaluation Programme involving 55 non-domestic buildings and a similar number of domestic projects was an eye-opener for participants that included clients, occupiers, architects, engineers as well as contractors.

AHR’s R&D team, with input from University College London, led the evaluation of seven non-domestic projects: three academies, two schools and two innovation centres over a period of four years.

The study found that the industry’s “compliance only” mind-set undermines design integration and compromises building performance outcomes. Taking occupiers largely out of the equation for energy certification, building regulations and sustainability certification does not leave many incentives for project teams to prioritise usability and long-term resilience. Coupled with the lack of a robust validation process between “as designed” vs “as-built”, it is no surprise that many new buildings and refurbishments end up more mechanised, less comfortable, consuming significantly more energy and costing more to maintain than intended.

The architecture of a building is an often overlooked aspect of building performance, but appeared to have a major impact on occupants’ perception of comfort, health and productivity

The architecture of a building is an often overlooked aspect of building performance, but appeared to have a major impact on occupants’ perception of comfort, health and productivity. Where occupiers were content with building design they gave high approvals for air quality and thermal comfort conditions that were identical to another building’s CO₂ and temperature readings, where occupiers had issues with the design and marked the exact same conditions as unsatisfactory.

AHR’s study has also found that where energy performance outcomes and maintenance were not a priority, the capital cost of unused and under-utilised systems, such as meters, BMS, LCZs, amounted to between 2-5% of capital cost. Misplaced value engineering, compromising long-term usability and resilience, was encountered on all the projects studied. Passive design features that are commonly challenged are window openings, floor to floor heights, thermal mass, entrance lobbies and passive ventilation stack sizes, which all contribute to a building’s resilience to overheating. Seasonal commissioning was omitted on all the education projects studied, resulting in compromised system set points and scheduling. All of these contribute to increased energy, management and maintenance costs and can affect the productivity of occupiers.

Targeting a nearly zero energy operation with a “fabric first” approach emerged as the most successful tack. Out of the 12 office buildings included in the Innovate UK study, Pool Innovation Centre (PIC) performed the best and Tremough Innovation Centre (TIC) third best in terms of energy use. The study also gathered occupier feedback with TIC and PIC achieving the 4th and 5th highest ratings respectively out of a benchmark set of 50 buildings. Both buildings have had excellent tenant uptake. These buildings were designed from the outset to maximise the benefits of natural ventilation, good daylighting, window design, high U values, shading and insulation, thus minimising the need for mechanically-operated (and energy-powered) heating, lighting and ventilation.

The BPEs highlighted potential savings and improvements on all the projects studied by AHR, with average energy savings estimated at tens of thousands of pounds per year for the larger more complex projects, dwarfing the cost of Soft Landings and BPEs. What is more, the research team found that over 70% of time spent on a BPE went on trying to extract usable energy data from a building. Where contractors are given the responsibility of gathering this data, the cost of the evaluation can be significantly lower.

As demonstrated by the recently completed award-winning Keynsham Civic Centre project by AHR, Max Fordham and Willmott Dixon, giving contractors energy performance targets and the responsibility to validate these with operational data is good for building performance and great for architecture.

Building performance evaluations used to be perceived as a financial burden and a professional indemnity risk. Yet the detailed evaluation of these buildings revealed substantial capital and whole life cost benefits in closing the feedback loop between design and operation for all stakeholders.

Judit Kimpian is director of sustainable architecture & research at architect practice AHR