Wintertime Greenhouse Gas Fluxes in Hemiboreal Drained Peatlands

Funding Information: Funding: This study was supported by the Estonian Research Council (IUT2-16 and PRG352); the EU through the European Regional Development Fund (Centre of Excellence EcolChange, Estonia) and by the Estonian State Forest Management Centre (projects LLOOM13056 “Carbon and nitrogen cycling in forests with altered water regime “, 2013–2016 and LLTOM17250 “Water level restoration in cut-away peatlands: development of integrated monitoring methods and monitoring”, 2017–2023).Peer reviewedPublisher PD

Urban stormwater retention capacity of nature-based solutions at different climatic conditions

Climate change and the continuing increase in human population creates a growing need to tackle urban stormwater problems. One promising mitigation option is by using nature-based solutions (NBS) – especially sustainable urban stormwater management technologies that are key elements of NBS action. We used a synthesis approach to compile available information about urban stormwater retention capacity of the most common sustainable urban drainage systems (SUDS) in different climatic conditions. Those SUDS targeting stormwater management through water retention and removal solutions (mainly by infiltration, overland flow and evapotranspiration), were addressed in this study. Selected SUDS were green roofs, bioretention systems (i.e. rain gardens), buffer and filter strips, vegetated swales, constructed wetlands, and water-pervious pavements. We found that despite a vast amount of data available from real-life applications and research results, there is a lack of decisive information about stormwater retention and removal capacity of selected SUDS. The available data show large variability in performance across different climatic conditions. It is therefore a challenge to set conclusive widely applicable guidelines for SUDS implementation based on available water retention data. Adequate data were available only to evaluate the water retention capacity of green roofs (average 56±20%) and we provide a comprehensive review on this function. However, as with other SUDS, still the same problem of high variability in the performance (min 11% and max 99% of retention) remains. This limits our ability to determine the capacity of green roofs to support better planning and wider implementation across climate zones. The further development of SUDS to support urban stormwater retention should be informed by and developed concurrently with the adaptation strategies to cope with climate change, especially with increasing frequency of extreme precipitation events that lead to high volumes of stormwater runoff

Support for the integration of green roof constructions within Chinese building energy performance policies

Green roofs could act as a thermal buffer in buildings and offer potential energy savings. However, the energy benefits from green roofs are not usually properly recognised by traditional building energy regulations. Building energy regulations are traditionally over-simplistic during the assessment of the energy performance of complex building constructions. In the case of green roof designs, it is essential that the assessment mechanisms should not ignore the complex heat and moisture balances within the green roof layers. In this paper, dynamic energy modelling that considers the complexity within the green roof layers is adopted to guide policy makers in China on the relationship between using specific thicknesses of roof insulation against green roof layers. Simulations are run for a residential building type by also considering different thermal envelope characteristics across eight large Chinese cities and within the five main climatic zones of China. Results that link the green roof characteristics with respective traditional insulation layers are produced for all cities and it is found that optimising the plant and soil characteristics of green roofs in some climates could substitute more than 125 mm of roof insulation, while less optimum green roof types could only replace about 25 mm of roof insulation

Haljaskatuste temperatuuri- ja veerežiim ning nõrgvee kvaliteet

In this PhD dissertation, three general benefits of planted roofs in Estonian climatic conditions are investigated. The temperature regime is analyzed on an existing LWA-based green roof (100 mm) and on a sod roof (150 mm) to determine the differences from typical planted roofs. In addition, 1x1.5 m roof plots were constructed and studied to see how non-insulated planted roofs acted in a cooler period. Three rainfall events and snow cover melting were measured. The runoff water quality of LWA-based green roofs and sod roofs was analyzed and compared with precipitation and conventional roofs to find at which scale water quality may appear. The measurement period was from June 2004 to April 2009. The investigations showed that planted roofs are sufficiently effective in Estonian climatic conditions. The green roof can provide a base roof with effective protection against the influence of intensive solar radiation. In summer and winter, temperatures under both the green roof and the sod roof showed a similar temperature run. In autumn and spring, the sod roof’s soil layer showed higher temperatures and lower amplitude than the green roof’s substrate layer. The studied green roof effectively retained light rain but cannot fully retain heavy rainstorm. Runoff water results showed that vegetated roofs influenced water quality to a considerable degree. While the temperature regime of the planted roofs has been investigated sufficiently, further investigations in fields of water quantity and quality are required to draw definite conclusions regarding the capability of planted roofs to retain water and improve water quality in Estonian climatic conditions. Käesoleva doktoritöö eesmärk on analüüsida katusehaljastuse kolme põhilist kasutegurit Eesti kliimas. Temperatuurirežiimi uuriti kergmuru- (100 mm) ja mätaskatusel (150 mm) eesmärgiga hinnata kahe tüüpilise haljaskatuse temperatuuri kõikumist alandavat mõju. Samuti teostati temperatuuriuuringud alt soojustamata 1x1.5 m suurustel katseplatvormidel. Veerežiimi jälgiti kolme vihmasaju ning lume sulaperioodi ajal eesmärgiga hinnata rohekatuste vee äravoolu hulka vähendavat ja algust edasilükkavat võimet. Veekvaliteedi analüüse võeti kergmurukatustelt ning mätaskatustelt, võrreldes neid sademete ning võrdluskatuste tulemustega eesmärgiga leida, millises skaalas võib vee kvaliteet varieeruda. Uuringud toimusid juunist 2004 kuni aprillini 2009. Teostatud uurimused näitasid, et haljaskatused on Eesti kliimatingimustes piisavalt efektiivsed. Tulemustest saab järeldada, et võrreldes tavakatustega on nii kergmuru- kui mätaskatus võimelised vähendama temperatuurikõikumiste mõju aluskatusele. Kahe tüübi tulemused olid suvel ja talvel sarnased, sügisel ja kevadel oli mätaskatuse pinnase temperatuur kõrgem ja väiksema amplituudiga. Vee kinnipidamisvõime tulemused näitasid, et haljaskatus suudab kinni pidada nõrga vihma, kuid paduvihma substraat kinni hoida ei suuda. Mõlemad haljaskatuste tüübid omavad sõltuvalt teguritest märkimisväärset mõju nõrgvee kvaliteedile. Kindlamate järelduste tegemiseks haljaskatuste efektiivsuse kohta Eesti tingimustes on vajalik teostada põhjalikumaid uuringuid igas valdkonnas, eeskätt aga nõrgvee kvantiteedi ning kvaliteedi osas