Parametric simulation study for green roof retrofit over high performance solar house prototype “EFdeN Signature”

The advantages of green roofs are well documented, ranging from heat island reduction, thermal comfort, air quality, stormwater management and energy savings for buildings. However, it has been shown that green roof retrofits are more effective in old, low efficiency buildings. This paper studies the possibility of retrofitting a high efficiency solar house with a green roof system being partially shaded, optimising its characteristics by means of parametric simulation. The input variables of the green roof system are: growth medium thickness, LAI (leaf area index) and height of plants. The output variables by which the different green roof systems are compared are: annual energy demand for heating and for cooling. The study concluded that the average reductions of energy consumption when retrofitting an efficient building with an extensive green roof are of 1.01% for heating and 4.61% for cooling, but optimising parameters (low LAI in winter, high LAI and height of plants in summer) can get reductions to 1.55% for cooling and 5.95% for cooling.

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Green roofs in building retrofits: outdoor microclimate benefits and energy savings

10.32920/ryerson.14639487 ◽

2021 ◽

Author(s):

Melissa Ann Furukawa

Keyword(s):

Energy Consumption ◽

Energy Demand ◽

Energy Savings ◽

Soil Depth ◽

Green Roof ◽

Green Roofs ◽

Area Index ◽

Heating And Cooling ◽

Building Energy Analysis ◽

The Impact

The impact of green roof retrofits on the local microclimate and energy consumption of a building is investigated. This research is based on a case study of Kerr Hall located on the Ryerson University campus in Toronto. The software ENVI-met is used to simulate the microclimate while EnergyPlus is used for the building energy analysis. Results indicate that increasing the leaf area index (LAI) of the green roof leads to increased cooling effect up to 0.4 degrees C during the day at pedestrian-level; however, more significant cooling is attained at the rooftop-level. The addition of the green roof reduced both the heating and cooling demands and improved indoor comfort levels. Energy demand reductions up to 3% were obtained with the green roof retrofits with the biggest contribution form from reduction in heating on the top floor. Increasing the soil depth had a larger impact on the energy consumption compared to increasing the LAI.

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Green roofs in building retrofits: outdoor microclimate benefits and energy savings

10.32920/ryerson.14639487.v1 ◽

2021 ◽

Author(s):

Melissa Ann Furukawa

Keyword(s):

Energy Consumption ◽

Energy Demand ◽

Energy Savings ◽

Soil Depth ◽

Green Roof ◽

Green Roofs ◽

Area Index ◽

Heating And Cooling ◽

Building Energy Analysis ◽

The Impact

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Modeling the Effect of Green Roof Systems and Photovoltaic Panels for Building Energy Savings to Mitigate Climate Change

Remote Sensing ◽

10.3390/rs12152402 ◽

2020 ◽

Vol 12 (15) ◽

pp. 2402 ◽

Cited By ~ 1

Author(s):

Yuanfan Zheng ◽

Qihao Weng

Keyword(s):

Climate Change ◽

Energy Demand ◽

Energy Savings ◽

Soil Depth ◽

Green Roofs ◽

Building Energy ◽

Positive Energy ◽

Solar Photovoltaic ◽

Area Index ◽

Pv Systems

Green roofs and rooftop solar photovoltaic (PV) systems are two popular mitigation strategies to reduce the net building energy demand and ease urban heat island (UHI) effect. This research tested the potential mitigation effects of green roofs and solar photovoltaic (PV) systems on increased buildings energy demand caused by climate change in Los Angeles County, California, USA. The mitigation effects were assessed based on selected buildings that were predicted to be more vulnerable to climate change. EnergyPlus software was used to simulate hourly building energy consumption with the proper settings of PV-green roofs. All buildings with green roofs showed positive energy savings with regard to total energy and electricity. The savings caused by green roofs were positively correlated with three key parameters: Leaf Area Index (LAI), soil depth, and irrigation saturation percentage. Moreover, the majority of the electricity-saving benefits from green roofs were found in the Heating, Ventilation, and Cooling (HVAC) systems. In addition, this study found that green roofs have different energy-saving abilities on different types of buildings with different technologies, which has received little attention in previous studies.

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Energy consumption and CO2 emission reductions trough refurbishment of residential buildings’ roofs by applying the green roof system: Case study

Thermal Science ◽

10.2298/tsci170530127d ◽

2018 ◽

Vol 22 (Suppl. 4) ◽

pp. 1217-1229 ◽

Cited By ~ 1

Author(s):

Katarina Djordjevic ◽

Olja Joksimovic ◽

Milica Jovanovic-Popovic

Keyword(s):

Energy Consumption ◽

Co2 Emissions ◽

Energy Savings ◽

Residential Buildings ◽

Structural Characteristics ◽

Green Roof ◽

Green Roofs ◽

Noticeable Effect ◽

Roof System ◽

Positive Effects

Climate changes which we are experiencing at the moment are affecting the entire globe. Serbia, as a developing country, is in the process of defining its own energy strategy and priorities when it comes to the problem of increased energy consumption in its building stock. Research shows that residential sector consumes the largest quantity of energy. CO2 emissions present another big problem which is in a direct correlation with energy consumption. Green roofs have multiple positive effects on buildings and their surroundings which make them a desirable option for retrofitting roofs. The aim of this paper is to investigate thermal properties of chosen green roof system and its potential to positively influence energy consumption for heating buildings and therefore CO2 emissions trough refurbishing existing old flat roofs. New Belgrade was chosen for this research for its unique urban characteristics - existence of large number of similar or identical buildings, which have same structural characteristics and similar surroundings. For the purpose of this paper, blocks 45 and 70 were chosen. Results of this research are applicable on all of the 132 buildings found at this location, which have total roof area of 90990m2. By calculating energy quantity needed for heating the building with the existing roof and two hypothetical models, which have green roof, it was possible to quantify energy savings, which are in a direct correlation with CO2 emissions. A control roof was introduced in order to examine if the proposed green roof possesses better characteristics than a traditional solution, most commonly used in Serbia. Apart from energy savings, overall impact of the green roof on the CO2 reduction per building was calculated. By multiplying these results, we drew the conclusion that a project such as greening roofs of existing residential buildings in blocks 45 and 70 would have a noticeable effect on both the energy savings and CO2 emissions.

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Evaluation of a High-Performance Solar Home in Loveland, Colorado

Journal of Solar Energy Engineering ◽

10.1115/1.2710248 ◽

2006 ◽

Vol 129 (2) ◽

pp. 226-234

Author(s):

Robert Hendron ◽

Mark Eastment ◽

Ed Hancock ◽

Greg Barker ◽

Paul Reeves

Keyword(s):

High Performance ◽

Energy Savings ◽

High Efficiency ◽

Building Envelope ◽

Operating Conditions ◽

Hot Water ◽

Space Heating ◽

Solar Water Heater ◽

Water Heater ◽

Solar Water

Building America (BA) partner McStain Neighborhoods built the Discovery House in Loveland, CO, with an extensive package of energy-efficient features, including a high-performance envelope, efficient mechanical systems, a solar water heater integrated with the space-heating system, a heat-recovery ventilator (HRV), and ENERGY STAR appliances. The National Renewable Energy Laboratory (NREL) and Building Science Consortium conducted short-term field-testing and building energy simulations to evaluate the performance of the house. These evaluations are utilized by BA to improve future prototype designs and to identify critical research needs. The Discovery House building envelope and ducts were very tight under normal operating conditions. The HRV provided fresh air at a rate of about 35L∕s(75cfm), consistent with the recommendations of ASHRAE Standard 62.2. The solar hot water system is expected to meet the bulk of the domestic hot water (DHW) load (>83%), but only about 12% of the space-heating load. DOE-2.2 simulations predict whole-house source energy savings of 54% compared to the BA Benchmark (Hendron, R., 2005 NREL Report No. 37529, NREL, Golden, CO). The largest contributors to energy savings beyond McStain’s standard practice are the solar water heater, HRV, improved air distribution, high-efficiency boiler, and compact fluorescent lighting package.

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Evaluation of a High-Performance Solar Home in Loveland, Colorado

Solar Energy ◽

10.1115/isec2005-76231 ◽

2005 ◽

Cited By ~ 1

Author(s):

Robert Hendron ◽

Mark Eastment ◽

Ed Hancock ◽

Greg Barker ◽

Paul Reeves

Keyword(s):

High Performance ◽

Energy Savings ◽

High Efficiency ◽

Building Envelope ◽

Operating Conditions ◽

Hot Water ◽

Space Heating ◽

Solar Water Heater ◽

Water Heater ◽

Solar Water

Building America (BA) partner McStain Neighborhoods built the Discovery House in Loveland, Colorado, with an extensive package of energy-efficient features, including a high-performance envelope, efficient mechanical systems, a solar water heater integrated with the space-heating system, a heat-recovery ventilator (HRV), and ENERGY STAR™ appliances. The National Renewable Energy Laboratory (NREL) and Building Science Consortium (BSC) conducted short-term field-testing and building energy simulations to evaluate the performance of the house. These evaluations are utilized by BA to improve future prototype designs and to identify critical research needs. The Discovery House building envelope and ducts were very tight under normal operating conditions. The HRV provided fresh air at a rate of about 75 cfm (35 l/s), consistent with the recommendations of ASHRAE Standard 62.2. The solar hot water system is expected to meet the bulk of the domestic hot water (DHW) load (>83%), but only about 12% of the space-heating load. DOE-2.2 simulations predict whole-house source energy savings of 54% compared to the BA Benchmark [1]. The largest contributors to energy savings beyond McStain’s standard practice are the solar water heater, HRV, improved air distribution, high-efficiency boiler, and compact fluorescent lighting package.

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The effect of drainage height on plant-species composition on a semi-arid green roof system

Israel Journal of Ecology and Evolution ◽

10.1163/22244662-bja10025 ◽

2021 ◽

Vol 67 (3-4) ◽

pp. 149-155

Author(s):

Har'el Agra ◽

Hadar Shalom ◽

Omar Bawab ◽

Gyongyver J. Kadas ◽

Leon Blaustein

Keyword(s):

Species Composition ◽

Plant Species ◽

Plant Diversity ◽

Urban Areas ◽

Green Roof ◽

Growing Season ◽

Green Roofs ◽

Plant Species Composition ◽

Roof System ◽

Semi Arid

Abstract Green roofs are expected to contribute to higher biodiversity in urban surroundings. Typically, green roofs have been designed with low plant diversity. However, plant diversity can be enhanced by controlling resource availability and creating distinct niches. Here we hypothesize that by using different drainage heights during the short plant-growing season in a semi-arid green roof system we can create distinct niches and plant communities. Our experiment took place at the University of Haifa, north Israel. We tested three different heights of drainage outlet: 10 cm under the surface of the substrate (Low), 1 cm under the surface of the substrate (Medium) and 3 cm above the surface of the substrate (High) on plant species-composition in green-roof gardens. Grasses cover was higher in High and Medium drainages while forbs cover was higher in Low drainage. Species richness was the highest in Low drainage while diversity indices showed the opposite trend. We conclude that by changing the height of the drainage we can create different niches and change species composition in a short time period of one growing season. This way we can create more diverse green roof communities and enhance biodiversity in urban areas, particularly in semi-arid regions.

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Prospects and restraints of green roofs for high-rise buildings in Sri Lanka

Built Environment Project and Asset Management ◽

10.1108/bepam-11-2018-0150 ◽

2019 ◽

Vol 10 (2) ◽

pp. 246-260

Author(s):

Subaskar Charles ◽

Herath Vidyaratne ◽

Damithri Gayashini Melagoda

Keyword(s):

Sri Lanka ◽

Questionnaire Survey ◽

Energy Savings ◽

Green Roof ◽

Green Roofs ◽

Sri Lankan ◽

Expert Interviews ◽

Content Type ◽

High Rise ◽

The Government

Purpose Green roofs are acknowledged as a method to substitute greenery washed out by the urbanization. They provide many ecological and sustainable benefits of greenery; reduce the adverse effects of high-rise building constructions. Though this concept is more popular across many countries over the past few decades, still, implementation of this technology in Sri Lanka is new and scant. Hence, the purpose of this paper is to identify and analyze the potential of green roofs in high-rise buildings in Sri Lanka. Design/methodology/approach The data collection was conducted through expert interviews and questionnaire survey. Expert interviews were carried out to validate the prospects and restraints identified through literature review to the Sri Lankan context and analyzed using content analysis. Questionnaire survey identified the most significant prospects and restraints using descriptive statistics and paired sample t-test. Purposive sampling was used to select participants. Findings Reduction of air pollution, aesthetical appearance, thermal benefits and energy savings, reduction of an urban heat island effect, the addition of points in the green rating system are the top most significant prospects that need to be highlighted in promoting green roof systems in Sri Lankan high rises. Less space allocation on rooftops, lack of technical competence and lack of awareness and research are restraints that need most effective elimination strategies to encourage green roof systems. Originality/value The first identified and quantified prospects and restraints for green roof system in Sri Lankan high-rise buildings can be utilized by the government, donors, multi-lateral agencies to promote the sustainable development in Sri Lanka and this knowledge could be used in different scale awareness programs. The value of this paper is such that the paper discusses the links of green roofs with the other facets of sustainability. The new legal reforms and amendments in Sri Lanka could potentially be pending with findings of this study.

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Analysis of roof greening technology impact on rain and meltwater retention

E3S Web of Conferences ◽

10.1051/e3sconf/202017511023 ◽

2020 ◽

Vol 175 ◽

pp. 11023

Author(s):

Elena Sysoeva ◽

Margarita Gelmanova

Keyword(s):

High Efficiency ◽

Green Roof ◽

Experimental Studies ◽

Green Roofs ◽

Climatic Conditions ◽

Water Runoff ◽

Substrate Thickness ◽

Runoff Reduction ◽

The Usa ◽

Analytical Review

Over the past 20 years, a large number of studies have been published on reducing storm runoff by various types of green roofs. This article analyzes the results of experimental studies presented in 39 publications on green roof runoff reduction in a climate similar to the climate of Russia: in Canada, the USA, Finland, Norway, France. An analytical review found that the ability of green roofs to retain rainfall varies from 20 to 99.5% depending on climatic conditions (duration and intensity of rains, duration of dry periods, solar radiation, temperature and humidity, wind conditions), the properties of green roof layers (moisture capacity of the substrate and a drainage layer, the substrate thickness), the type of vegetation, the geometry of a green roof (slope and orientation). Green roofs can be a useful tool for reducing urban storm water runoff. However, in order to ensure high efficiency, it is necessary to use green roof technology with other measures to reduce runoff.

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Energy Saving by ESCO (Energy Service Company) Project in Japanese Hospital

Volume 6: Emerging Technologies: Alternative Energy Systems; Energy Systems: Analysis, Thermodynamics and Sustainability ◽

10.1115/imece2009-10576 ◽

2009 ◽

Cited By ~ 1

Author(s):

S. Okamoto

Keyword(s):

Energy Demand ◽

Energy Savings ◽

High Efficiency ◽

Hospital Setting ◽

Electrical Heating ◽

Public Network ◽

Service Company ◽

Heating And Cooling ◽

Energy Service ◽

Energy Service Company

This paper describes a study starting from an analysis of typical energy demand profiles in a hospital setting followed by the case study of a cogeneration system (CGS) by an ESCO (Energy Service Company) project. The concept is a future autonomous system for the combined generation of electrical, heating and cooling energy in the hospital. The driving cogeneration units are two high-efficiency gas engines; this is used to produce the electrical and heat energy. Gas engine is used as a driving unit because of high needs for electrical and heating energy. The natural gas-fuelled reciprocating engine is used to generate 735kW of power. In our case electrical energy will be used only in the Hospital. A deficit in electricity can be also purchased from the public network. The generated steam will be used to drive three steam-fired absorption chillers and delivered to individual consumers of heat. This system is capable of doing simultaneous heating and cooling. No obstacles were recognized for the technical feasibility of CGS. The average ratio between electric and thermal load in the Hospital is suitable to make CGS system operate. An analysis performed for a non-optimized CGS system predicted a large potential for energy savings.

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