Achieving the Daylight Credit in LEED v4/v4.1 BD+C
Green Building Team on September 28, 2019
The Daylight credit in LEED has always been one that many projects target; it improves the well-being and performance of the building’s occupants, reduces the need for electric lighting, and can improve energy costs. With LEED v4, the credit has evolved to provide occupants with superior daylighting. The changes include an increased Annual Sunlight Exposure (ASE) target, as well as the removal of the prescriptive option. However, these changes can make it more challenging to achieve at extreme northern latitudes, especially with a limit (3,000 lux) to the amount of daylight at 9 a.m. and 3 p.m.
These marketplace concerns have alerted the CaGBC Materials Technical Advisory Group (MR TAG) for changes needed to make Daylighting more accessible for Canadian projects. Through cooperation with other green building councils, the MR TAG learnt about an Alternate Compliance Path (ACP) that the Sweden Green Building Council (SGBC) was proposing to the USGBC (ACP Pilot credit, approved July 2019). This Nordic ACP proposes an alternative methodology for calculating daylight performance according to the European prEN17037 standard, and calculations are based on available daylight hours rather than office hours.
The CaGBC LEED Daylight Taskforce and simulation of Canadian projects
MR TAG recommended the formation of the CaGBC LEED Daylight Taskforce to facilitate LEED v4 Daylight credit achievement in northern latitudes and investigate the Nordic ACP use for Canada. The taskforce was created with volunteers from MR TAG, SGBC members, and other Canadian professionals, and performed climate-based daylight simulations on four Canadian LEED projects. Analysis of the options under LEED Canada NC 2009, the Nordic ACP, and the newly released LEED v4.1 were all modelled for comparison. LEED v4.1 was chosen instead of LEED v4 as it was regarded by the taskforce to be more achievable.
Simulation results demonstrated that three projects had the potential to achieve the credit with LEED Canada NC 2009 and LEED v4.1 Option 1; while two projects had the potential to achieve the credit with LEED v4.1 Option 2 and Nordic ACP Option 1. No projects could achieve the credit with Nordic ACP Option 2.
LEED v4 Option 1 challenges (e.g. thresholds, time, expense) made it unlikely to be utilized by most Canadian projects, while LEED v4.1 Option 1 offers an improvement with the modification of the ASE requirements. The previous advantages of adopting the European Nordic ACP path (use of daylight hours vs operation hours, shading and no requirement for ASE) did not offer a simplified compliance path for Canadian Projects as compared with LEED v4.1, and would require costly and time-consuming simulations compared to LEED v4.1.
The LEED v4 Daylight Taskforce concluded that the newly released LEED v4.1 credit appears to offer a better option and more achievable path for Canadian project teams to obtain points under the Daylighting credit with the new thresholds (depending on the option), compared to the Nordic ACP.
The CaGBC MR TAG is open to continuing to collaborate with the Sweden Green Building Council and other green building councils around the world to increase the accessibility of the Daylight credit for projects in Northern latitudes, while still providing quality daylight to occupants. The CaGBC would like to give special thanks and appreciation to all members of the Daylight Taskforce for their contribution and time:
- Government of New Brunswick – Pam Barteaux (Taskforce Chair) and Eren Wuest,
- Provencher_Roy – Guillaume Martel (MR TAG Chair),
- Architecture49 Inc. – Sarah Chernis and Janelle Harper,
- BAU – Paul Rogers, Angel A. Perez Morata and Anton Hendrix,
- Footprint – Jessica Cushing and Lyle Scott,
- Integral – Ellie Niakan, Emily Codlin and Mike Martinez,
- LINK Arkitektur – Vaia Vakouli,
- Perkins+Will – Cheney Chen,
- Stantec – Marc Trudeau and Charline Cormier,
- Sweden Green Building Council – Sue Clark,
WSP – David Rulff and Stacy Sun.