"Daylight paradox- evaluation based on LEED v4 and prEN-17037 Daylight of Buildings" by Anne Iversen
Senior Sustainability Engineer
Lecture from the 7th VELUX Daylight Symposium “Healthy & climate-friendly architecture– from knowledge to practice” that took place in Berlin on 3-4 May 2017. For more information visit http://thedaylightsite.com
“Daylighting paradox – Evaluation of daylight based on LEED v4 and prEN-17037 Daylight of Buildings” by Anne Iversen, Maria Garcia Alvarez, Mathias Sønderskov Nielson, Jakob Strømann-Andersen. The study presented in this paper evaluates the daylight conditions based on LEED v4 and the new draft European daylight standard prEN-17037 in the new Nordea Bank Headquarters located in Ørestad North Copenhagen Denmark.
The headquarter building is selected as a case study because it achieved the highest score in the inter- national certification system LEED v3, with a Platinum score, and the building obtained two credit points under the category Environmental Quality. The building is currently under construction and will be inaugurated in April 2017. This paper focuses on evaluating daylight according to LEED v4, Option 1, which is simulations of spatial daylight conditions. In this method Spatial Daylight Autonomy (sDA) and Annual Sunlight Exposure (ASE) metrics define daylight and direct sunlight conditions in the regularly occupied areas. Projects pursuing LEED v4 certification need to fulfill ASE requirement to be awarded for sDA performance.
The daylighting paradox is, however, that fulfilling sDA fails to satisfy the ASE requirement. Hence, designing to achieve the highest LEED score for daylighting and, in LEED terms, create a daylight-optimized building is not feasible. Additionally, the Annual Sunlight Exposure is a metric describing the hours with acceptable amount of direct sun. In practice, this metric is often translated into a parameter describing a glare threshold, that is, if you are within 10% ASE you have a building with acceptable direct sunlight conditions. However, optimizing for ASE will still give rise to 250 hours over a year where direct horizontal illuminance levels are above 1000lux, which might be glary. During 2016 a draft for a new European daylight standard prEN- 17037 became available to the public.
The standard proposes a daylight evaluation method, where climate based simulations are converted to a site specific daylight factor evaluation. Furthermore, the standard proposes an evaluation method for glare in buildings based on the daylight glare probability index. The methods outlined in LEED v4 Option 1 for daylight and direct sunlight conditions and prEN-17037 for daylight and glare are compared and discussed in the paper. Anne Iversen currently acts as a Senior Sustainability Engineer at Henning Larsen. She holds a M.Sc. and Ph.D. in Civil Engineering, specializing in energy-efficient buildings with an emphasis on daylight performance.
She demonstrates a broad experience in the implementation of complex temporal parameters such as light, shade, and the sun, supported by her former position as a researcher for SBi (Staten’s Byggeforskningsinstitut) - internationally recognized to provide advanced research for the built environment. She has contributed to numerous publications, including Daylight Calculations in Practice for Sbi and Investigation of Architectural Strategies in Relation to Daylight and Integrated Design for Journal of Green Buildings. Anne underlines both quantitative metrics from daylight simulations and qualitative experiences of the indoor environment, as the basis premise for high building performance. Anne holds an important role in the Department of Sustainability and forms the unique link between state-of–the-art research and practice. She is a key figure in the design of the new Nordea Bank HQ in Copenhagen, as well as in the extension of Herlev Hospital in Denmark, where her sustainable visions have secured and corroborated high-quality design results.