December is particular time of the year, when we look back in the year that is ending, and more importantly, we make plans for the year to come. New Year’s resolutions are often focused on things that really matter – healthy and happy life. Our personal well-being is connected also to the healthy environment around us. So let’s think today about New year resolution for healthier environment. We shall preserve and safeguard natural resources and green areas around us, and when possible - create a new green space.
https://goloadup.com/eco-friendly-new-years-resolutions/
Dive into new year with new green space
If you are considering investment into better living environment, think about green roof, either on new building or retrofitting existing rooftop. Green breathing rooftops do much more than just add aesthetic value to urban landscapes. Green roofs act as natural insulators, significantly reducing the need for additional heating and cooling. They absorb and store solar energy, helping to regulate indoor temperatures and lower energy costs year-round. In warmer climates, the lush vegetation on green roofs provides a cooling effect, reducing the urban heat island phenomenon and creating a more comfortable living environment. Conversely, in colder regions, green roofs serve as a blanket, retaining heat and offering an additional layer of protection against the environmental elements. Beside this, green spaces contribute to biodiversity, reduce stormwater runoff, and improve air quality, making them a multifaceted solution for sustainable urban living.
https://finance-commerce.com/2024/07/sustainable-green-roofs-find-global-resurgence/
Let’s check some numbers
Study, recently done in case of Mediterranean climate (Qadourah, 2024) shows that extensive green roofs can passively improve energy efficiency, indoor operative temperature and carbon emissions in Mediterranean climate region. Results show that green roofs reduce energy consumption, stabilize indoor temperatures and decrease carbon emissions compared to typical uninsulated concrete roofs. The green roof reduces CO2 by up to 5.8 % compared to the typical roof. This effect helps mitigate climate change and lower atmospheric CO2 levels. Moreover, green roofs on existing buildings might lower energy usage by 12.6 %, based on this study's parameters. Increased soil thickness has a negligible impact on total energy conservation. Regarding the role of soil thickness, this study confirms previous findings – thinner soil layer was better performing in summertime then thicker layer (Yoshimi, 2016). Bevilacqua et al. (2020) use experimental data to identify that a non-insulated green roof provides as much as 43.8% cooling energy savings and 40.9% winter energy savings in a Mediterranean climate. If roof is insulated, this effect tends to be smaller.
Jamei et al. (2023) report that the reduction in cooling load is maximum (mean 50.2%) in temperate climate zones for well-irrigated green roofs. The effectiveness in saving cooling load reduces in hot–humid and hot-dry climate zones with means of 10% and 14.8% respectively. Regarding water scarcity, drought-tolerant vegetation that thrives with minimal water input can significantly reduce irrigation needs, and the use of recycled greywater from the building to water green roofs. Moreover, extended periods of initial irrigation treatment, and choosing lightweight, well-draining substrates that retain moisture efficiently can optimize water use – this is where Green roll layer as unique solution in Urbanscape green roof system, will play a significant role. Read more about the system here: https://blog.urbanscape-architecture.com/the-significance-of-lightweight-in-green-roof-systems-comparing-different-designs
Green roofs have significant impact on the thermal response of the building’s envelope in the winter time conditions as well. Water in growing media enhance green roof thermal capacity and can effectively store heat from solar radiation which reduces roof heat losses. At freezing ambient air conditions, the process of water freezing further improves the energy efficiency of green roofs (Arkar et al., 2019). Later, Wang et al (2024) pointed out different studies which show significant results, such as:
- a non- insulated green roof provides as much as 43,8% cooling energy savings and 40.9% winter energy savings in a Mediterranean climate.
- green roofs can reduce a building's energy use by 30.7% in hot-humid zones and 71% heating load in cold-dry zones optimized green roofs could increase 12.8% comfort and reduce 14% energy use.
Plants' selection matters too
In Hong Kong, the energy-saving potential of two different types of plants in two green roofs (peanut and sedum) was quantified. The green roof with Sedum plants resulted in energy demand reduction, whereas green roof with peanut led to increased summer cooling loads. A similar result was achieved in Toronto, Canada, where a sedum roof resulted in better energy performance compared with a grass roof. The energy and thermal behaviour of extensive green roofs with different plant species in Michigan, USA was evaluated, and the findings indicated that green roofs with sedum plants achieved better performance than green roofs with herbaceous plants (Jamei et al., 2023). The natural properties of Sedum plants make this hardy, shallow rooted plant very suitable for green roofing. Family of succulent plants consists of several hundred species and thousand of different varieties. These plants can easily deal with sun, wind and drought and require little maintenance. Sedum is largely preferred as a roof covering due to its great varieties and provides a great habitat for insects, including butterflies. Urbanscape green roof system comprises carefully selected mix of Sedum varieties:
https://www.urbanscape-architecture.com/sl/resitve/sistem-zelene-strehe-urbanscape/
Sweden study case
https://www.urbanscape-architecture.com/projects/karolinska-hospital/
Karolinska hospital is located in cold climate zone, Sweden. Average monthly temperatures range from -2°C to 18°C, relative humidity up to 87%, and 73-mm rainfall. With a size of approx. 330.000 m2, including 730 patient care rooms and 35 operating halls, it is the largest BIM project in Sweden. Urbanscape, the extensive lightweight green roof system, plays important part in advanced performance in terms of stormwater control and energy efficiency. The buildings’ energy consumption for electricity, heating and cooling is 110 kWh/m2 per year – that is less than half of most existing hospitals today.
Dear readers, we wish you a happy, healthy New Year and invite you to follow us in 2025. Don’t forget, every m2 of greenery counts. 2025, go green!
https://www.urbanscape-architecture.com/projects/karolinska-hospital/
Literature:
Arkar, et al., 2019. Hydrological and Thermal Response of green roofs in different climate conditions. IOP Conf. Ser.: Earth Environ. Sci.
Bevilacqua P., et al., 2020. Green roofs in a Mediterranean climate: energy performances based on in-situ experimental data. Renew Energy
Jamei, E. et al., 2023. Green roof and energy-role of climate and design elements in hot and temperate climates.
Quadourah, J. A., 2024. Energy efficiency evaluation of green roofs as a passive strategy in the Mediterranean climate. Results in Enginnering, Vol. 23, September 2024.
Yoshimi, J, 2016. The Thermal Effects of Green Roofs and Walls : Experimentation on the Performance of Vegetated Building Envelopes in the UK.
Wang M., et al., 2024. Unlock city scale energy saving and peak load shaving potential of green roofs by GIS – informed urban building energy modelling. Applied energy vol 366, 2024.
