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Water 2018, 10(3), 263;

Hydrological Performance of LECA-Based Roofs in Cold Climates

Department of Civil and Environmental Engineering, Norwegian University of Science and Technology, 7491 Trondheim, Norway
Leca International, Årnesvegen 1, 2009 Nordby, Norway
Author to whom correspondence should be addressed.
Received: 15 December 2017 / Revised: 27 February 2018 / Accepted: 28 February 2018 / Published: 3 March 2018
(This article belongs to the Special Issue Sponge Cities: Emerging Approaches, Challenges and Opportunities)
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Rooftops represent a considerable part of the impervious fractions of urban environments. Detaining and retaining runoff from vegetated rooftops can be a significant contribution to reducing the effects of urbanization, with respect to increased runoff peaks and volumes from precipitation events. However, in climates with limited evapotranspiration, a non-vegetated system is a convenient option for stormwater management. A LECA (lightweight expanded clay aggregate)-based roof system was established in the coastal area of Trondheim, Norway in 2016. The roof structure consists of a 200 mm-thick layer of LECA® lightweight aggregate, covered by a concrete pavement. The retention in the LECA-based roof was estimated at 9%, which would be equivalent to 0.27 mm/day for the entire period. The LECA-based configuration provided a detention performance for a peak runoff reduction of 95% (median) and for a peak delay of 1 h and 15 min (median), respectively. The relatively high moisture levels in the LECA-based roof did not affect the detention performance. Rooftop retrofitting as a form of source control may contribute to a change in runoff characteristics from conventional roofs. This study of the LECA-based roof configuration presents data and performance indicators for stormwater urban planners with regard to water detention capability. View Full-Text
Keywords: detention; cold climate; hydrological performance; LECA-based roof; lightweight aggregate; sustainable drainage systems (SuDS); water-detaining non-green roof detention; cold climate; hydrological performance; LECA-based roof; lightweight aggregate; sustainable drainage systems (SuDS); water-detaining non-green roof

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Hamouz, V.; Lohne, J.; Wood, J.R.; Muthanna, T.M. Hydrological Performance of LECA-Based Roofs in Cold Climates. Water 2018, 10, 263.

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