Energy Performance of Sustainable Roofing Systems

2013 ◽  
Author(s):  
David J. Sailor ◽  
Prem Vuppuluri
Keyword(s):  
Energy Use ◽  
Green Roof ◽  
Green Roofs ◽  
Energy Performance ◽  
Office Building ◽  
Solar Photovoltaic ◽  
Conduction Model ◽  
Exterior Surface ◽  
Photovoltaic Array ◽  
Heating And Cooling

This study presents efforts to analyze how sustainable roofing technologies can contribute to the energy budget of buildings, and the resulting implications for heating and cooling energy use. The data analyzed in this study were obtained from a field experiment performed on a four story warehouse/office building in Portland, Oregon USA. The building’s roof includes a 216 panel, 45.6 kW solar photovoltaic array in combination with 576 m2 of vegetated green roofing. While most of the surface consists of green roof shaded by photovoltaic panels, the roof also has test patches of dark membrane, white membrane and un-shaded green-roofing. Interior and exterior surface temperatures were monitored over a period of two years and heat flux into the building is estimated using a finite difference conduction model. On average, the black roof membrane was the only roof that caused a net heat gain into the building in the summer. In the winter, all four roofing technologies resulted in net heat losses out of the building. Both the PV-shaded and un-shaded green-roofs indicated a net heat loss out of the interior of the building during both the summer and winter. This latter effect is largely a result of green-roof evaporative cooling — which can benefit air conditioning demand in summer but may be undesirable during heating-dominated seasons.

scholarly journals Impact of Vegetation, Substrate, and Irrigation on the Energy Performance of Green Roofs in a Mediterranean Climate

Water ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 2016 ◽  
Author(s):  
Gomes ◽  
Silva ◽  
Valadas ◽  
Silva
Keyword(s):  
Mediterranean Climate ◽  
Energy Use ◽  
Soil Depth ◽  
Green Roof ◽  
Green Roofs ◽  
Energy Performance ◽  
Area Index ◽  
Vegetation Height ◽  
Energy Needs ◽  
Irrigation Levels

Green roof energy performance is still a challenging topic, namely in a Mediterranean climate since it depends on building characteristics, roof type, and also on climatic conditions. This paper evaluates green roof buildings’ energy needs and use in a Mediterranean climate. An experimentally calibrated numerical model was used to perform a parametric analysis and identify the influence of key parameters in heating and cooling energy needs, as well as annual energy use. The vegetation height, the soil depth, and LAI (leaf area index) were identified as the key parameters. The irrigation levels were also crucial for the energy performance of green roofs, particularly during the summer period and in a Mediterranean climate. Heating energy needs were mainly associated with soil depth due to higher thermal resistance, whereas cooling energy needs depended mostly on LAI, which influenced evapotranspiration and shading effects. A reduction of soil depth from 1.0 m to 0.1 m increased winter energy needs by up to 140%, while low values of LAI increased cooling energy needs up to 365%. Annual energy use in a Mediterranean climate showed a higher dependence on soil depth, with oscillations of up to 115%, followed by LAI and vegetation height. Finally, irrigation levels impacted the annual energy use more significantly for lower watering flow rates. Reductions of about 500% were obtained when changing watering flowrates from 0 mm/day to 6 mm/day in intensive green roofs. Since green roofs with native species expect low values of watering, this may increase their cooling energy needs.

scholarly journals Effects of Architectural Space Layouts on Energy Performance: A Review

2020 ◽  
Vol 12 (5) ◽  
pp. 1829 ◽  
Author(s):  
Tiantian Du ◽  
Sabine Jansen ◽  
Michela Turrin ◽  
Andy van den Dobbelsteen
Keyword(s):  
Natural Ventilation ◽  
Energy Use ◽  
Building Design ◽  
Energy Performance ◽  
Office Building ◽  
Design Parameters ◽  
Heating And Cooling ◽  
Design Variables ◽  
Occupant Comfort ◽  
The Uk

As one of the most important design tasks of building design, space layout design affects the building energy performance (BEP). In order to investigate the effect, a literature review of relevant papers was performed. Ten relevant articles were found and reviewed in detail. First, a methodology for studying the effects of space layouts on BEP were proposed regarding design variables, energy indicators and BEP calculation methods, and the methodologies used in the 10 articles were reviewed. Then, the effects of space layouts on energy use and occupant comfort were analysed separately. The results show that the energy use for heating, cooling, lighting and ventilation is highly affected by space layouts, as well as thermal and visual comfort. The effects of space layouts on energy use are higher than on occupant comfort. By changing space layouts, the resulting reductions in the annual final energy for heating and cooling demands were up to 14% and 57%, respectively, in an office building in Sweden. The resulting reductions in the lighting demand of peak summer and winter were up to 67% and 43%, respectively, for the case of an office building in the UK, and the resulting reduction in the air volume supplied by natural ventilation was 65%. The influence of other design parameters, i.e., occupancy and window to wall ratio, on the effects of space layouts on BEP was also identified.

scholarly journals IMPACT OF GREEN ROOF ON HEATING AND COOLING IN CONTEXT OF DIFFERENT CLIMATIC ZONES IN INDIA

2021 ◽  
pp. 436-440
Author(s):  
Ar. Ankur Bhardwaj ◽  
Dr. Shweta Chaudhary ◽  
Ar.Kirti Varandani
Keyword(s):  
Urban Areas ◽  
Green Roof ◽  
Green Roofs ◽  
Climatic Zones ◽  
Sustainable Living ◽  
Secondary Sources ◽  
Heating And Cooling ◽  
The World ◽  
Depth Study ◽  
Rainwater Runoff

The ecological, social and visual commitments that green roofs can make towards sustainable living in more intensified urban centres are generally recognized around the world. Green roof is one such sustainable methodology, utilization of which causes us in insulating the buildings and, subsequently contributing to better energy proficient execution of the same. Green roofs additionally give environment to various species, lessen the rainwater runoff and better deal with the carbon-dioxide cycle. In spite of these advantages, Green roofs are not as basic an element in India as they are in other European and American urban areas. In this paper an attempt has been made to enhance the advantages of this innovation in India. Green roofs systems looks simple in terms of setting up, but actually very complex in maintaining and achieving sustainability. In depth study of green roofs, historic background, climatic zones, impacts of green roofs on heating and cooling, benefits, problems and opportunities is done with the help of data taken from secondary sources like books, magazines and published literature (articles, journals, conference proceedings) form various e-libraries and other online platforms. KEY WORDS: Heating, Cooling, Green Roof, Sustainability)

scholarly journals Comparison Evaluations of VRF and RTU Systems Performance on Flexible Research Platform

2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Je-hyeon Lee ◽  
Piljae Im ◽  
Jeffrey D. Munk ◽  
Mini Malhotra ◽  
Min-seok Kim ◽  
...  
Keyword(s):  
Energy Use ◽  
Energy Savings ◽  
Thermal Conditions ◽  
The United States ◽  
Energy Performance ◽  
Coefficient Of Performance ◽  
Part Load ◽  
Variable Air Volume ◽  
Heating And Cooling ◽  
Load Conditions

The energy performance of a variable refrigerant flow (VRF) system was evaluated using an occupancy-emulated research building in the southeastern region of the United States. Full- and part-load performance of the VRF system in heating and cooling seasons was compared with a conventional rooftop unit (RTU) variable-air-volume system with electric resistance heating. During both the heating and cooling seasons, full- and part-load conditions (i.e., 100%, 75%, and 50% thermal loads) were maintained alternately for 2 to 3 days each, and the energy use, thermal conditions, and coefficient of performance (COP) for the RTU and VRF system were measured. During the cooling season, the VRF system had an average COP of 4.2, 3.9, and 3.7 compared with 3.1, 3.0, and 2.5 for the RTU system under 100%, 75%, and 50% load conditions and resulted in estimated energy savings of 30%, 37%, and 47%, respectively. During the heating season, the VRF system had an average COP ranging from 1.2 to 2.0, substantially higher than the COPs of the RTU system, and resulted in estimated energy savings of 51%, 47%, and 27% under the three load conditions, respectively.

scholarly journals Innovative HVAC System Using an Integrated Greenhouse for a Virtual Low Energy Office Building

2019 ◽  
Vol 111 ◽  
pp. 04011
Author(s):  
Catalin Lungu ◽  
Florin Baltaretu
Keyword(s):  
Natural Ventilation ◽  
Energy Use ◽  
Ventilation System ◽  
Office Building ◽  
Treatment Unit ◽  
Heating And Cooling ◽  
Venturi Effect ◽  
Innovative System ◽  
Air Intake ◽  
Air Humidification

In this paper the authors describe a HVAC innovative system using an integrated greenhouse for heating and cooling an office building. The ventilation system allows natural (night) or mechanical ventilation and the passive cooling during the summer, including cold storage in the building structure and the PCM plywood and the refrigeration energy use during the day. Natural ventilation occurs when the wind or the Venturi effect, created by the « hat » that supports the photovoltaic panels, is strong enough; otherwise, a variable speed exhaust fan mounted on top of the building is used. The plants inside the greenhouse can produce O2 under certain conditions necessary for refreshing the ventilation air. The environment of the greenhouse allows air humidification naturally, without the use of humidifiers. If the greenhouse is sufficiently insulated in winter, it can be used in the ventilation process: the air intake from offices through the greenhouse, humidified and enriched in O2 (premixed, if necessary, with fresh air) reaches the general air treatment unit, and then sent back. The process is similar in the summer, but without recirculation, due to the humidity of the air extracted from offices. Stale air humidification enhances the thermal transfer process from the desiccant collector.

scholarly journals Effects of Extensive Green Roofs on Energy Performance of School Buildings in Four North American Climates

Water ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 6 ◽  
Author(s):  
Milad Mahmoodzadeh ◽  
Phalguni Mukhopadhyaya ◽  
Caterina Valeo
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Plant Height ◽  
Green Roof ◽  
Green Roofs ◽  
Energy Performance ◽  
Design Parameters ◽  
Soil Thickness ◽  
Area Index ◽  
Roof Design

A comprehensive parametric analysis was conducted to evaluate the influence of the green roof design parameters on the thermal or energy performance of a secondary school building in four distinctively different climate zones in North America (i.e., Toronto, ON, Canada; Vancouver, BC, Canada; Las Vegas, NV, USA and Miami, FL, USA). Soil moisture content, soil thermal properties, leaf area index, plant height, leaf albedo, thermal insulation thickness and soil thickness were used as design variables. Optimal parameters of green roofs were found to be functionally related to meteorological conditions in each city. In terms of energy savings, the results showed that the light-weight substrate had better thermal performance for the uninsulated green roof. Additionally, the recommended soil thickness and leaf area index for all four cities were 15 cm and 5 respectively. The optimal plant height for the cooling dominated climates is 30 cm and for the heating dominated cities is 10 cm. The plant albedo had the least impact on the energy consumption while it was effective in mitigating the heat island effect. Finally, unlike the cooling load, which was largely influenced by the substrate and vegetation, the heating load was considerably affected by the thermal insulation instead of green roof design parameters.

scholarly journals Thermal mass impact on energy performance of a low, medium and heavy mass building in Belgrade

2012 ◽  
Vol 16 (suppl. 2) ◽  
pp. 447-459 ◽  
Author(s):  
Bojan Andjelkovic ◽  
Branislav Stojanovic ◽  
Mladen Stojiljkovic ◽  
Jelena Janevski ◽  
Milica Stojanovic
Keyword(s):  
Building Energy ◽  
Energy Performance ◽  
Office Building ◽  
Energy Requirements ◽  
Space Heating ◽  
Thermal Mass ◽  
Mass Concrete ◽  
Building Energy Performance ◽  
Heating And Cooling ◽  
Space Cooling

Heavy mass materials used in building structures and architecture can significantly affect building energy performance and occupant comfort. The purpose of this study was to investigate if thermal mass can improve the internal environment of a building, resulting in lower energy requirements from the mechanical systems. The study was focused on passive building energy performance and compared annual space heating and cooling energy requirements for an office building in Belgrade with several different applications of thermal mass. A three-dimensional building model was generated to represent a typical office building. Building shape, orientation, glazing to wall ratio, envelope insulation thickness, and indoor design conditions were held constant while location and thickness of building mass (concrete) was varied between cases in a series of energy simulations. The results were compared and discussed in terms of the building space heating and cooling energy and demand affected by thermal mass. The simulation results indicated that with addition of thermal mass to the building envelope and structure: 100% of all simulated cases experienced reduced annual space heating energy requirements, 67% of all simulated cases experienced reduced annual space cooling energy requirements, 83% of all simulated cases experienced reduced peak space heating demand and 50% of all simulated cases experienced reduced peak space cooling demand. The study demonstrated that there exists a potential for reducing space heating and cooling energy requirements with heavy mass construction in the analyzed climate region (Belgrade, Serbia).

scholarly journals Technical considerations in green roof retrofit for stormwater attenuation in the Central Business District

2015 ◽  
Vol 33 (1) ◽  
pp. 36-51 ◽  
Author(s):  
Sara Wilkinson ◽  
Jessica Lamond ◽  
David G Proverbs ◽  
Lucy Sharman ◽  
Allison Heller ◽  
...  
Keyword(s):  
Built Environment ◽  
Focus Groups ◽  
Energy Use ◽  
Relevant Literature ◽  
Green Roof ◽  
Green Roofs ◽  
Environmental Benefits ◽  
Design Stage ◽  
Due Diligence ◽  
Content Type

Purpose – The key aspects that built environment professionals need to consider when evaluating roofs for the purpose of green roof retrofit and also when assessing green roofs for technical due diligence purposes are outlined. Although green or sod roofs have been built over many centuries, contemporary roofs adopt new approaches and technologies. The paper aims to discuss these issues. Design/methodology/approach – A mixed methods design based on a systematic review of relevant literature from parallel disciplines was used to identify and quantify the social, economic and environmental benefits of retrofitted green roofs in commercial districts. The technical issues of concern were drawn from a desk-top survey of literature and from stakeholder focus groups undertaken in Sydney in 2012. Findings – There are perceptions amongst built environmental practitioners that may act as artificial barriers to uptake. There is little direct experience within built environment professionals and practitioners, along with a fear of the unknown and a risk averse attitude towards perceived innovation which predicates against green roof retrofit. Furthermore projects with green roofs at inception and early design stage are often “value engineered” out of the design as time progresses. There is a need for best practice guidance notes for practitioners to follow when appraising roofs for retrofit and also for technical due diligence purposes. Research limitations/implications – The focus groups are limited to Sydney-based practitioners. Although many of these practitioners have international experience, few had experience of green roofs. A limited number of roof typologies were considered in this research and some regions and countries may adopt different construction practices. Practical implications – In central business districts the installation of green roof technology is seen as one of the main contributors to water sensitive urban design (WSUD). It is likely that more green roofs will be constructed over time and practitioners need knowledge of the technology as well as the ability to provide best advice to clients. Originality/value – The benefits of green roofs as part of WSUD are increasingly being recognised in terms of reduced flood risk, reduced cost of drainage, improved water quality and lower energy use, as well as other less tangible aspects such as aesthetics and amenity. This research highlights the lack of understanding of the short- and long-term benefits, a poor appreciation and awareness of these benefits; a lack of technical knowledge and issues to be considered with regard to green roofs on behalf of practitioners. The study has highlighted the need for specific training and up-skilling in these areas to provide surveyors with the technical expertise needed. There is also a need to consider how the emerging retrofit and adaptation themes are best designed into the curriculum at both undergraduate and postgraduate levels. Clearly, if the potential benefits of green roofs are to be realised in the future, building professionals need to be fully conversant with the technology and be able to provide reliable and accurate advice.

scholarly journals Impact of orientation and building envelope characteristics on energy consumption case study of office building in city of Nis

2018 ◽  
Vol 22 (Suppl. 5) ◽  
pp. 1499-1509
Author(s):  
Miomir Vasov ◽  
Jelena Stevanovic ◽  
Veliborka Bogdanovic ◽  
Marko Ignjatovic ◽  
Dusan Randjelovic
Keyword(s):  
Energy Consumption ◽  
Early Stage ◽  
Building Energy ◽  
Energy Performance ◽  
Building Envelope ◽  
Office Building ◽  
Climatic Data ◽  
Building Energy Efficiency ◽  
Maximum Difference ◽  
Heating And Cooling

Buildings are one of the biggest energy consumers in urban environments, so its efficient use represents a constant challenge. In public objects and households, a large part of the energy is used for heating and cooling. The orientation of the object, as well as the overall heat transfer coefficient (U-value) of transparent and non-transparent parts of the envelope, can have a significant impact on building energy needs. In this paper, analysis of the influence of different orientations, U-values of envelope elements, and size of windows on annual heating and cooling energy for an office building in city of Nis, Serbia, is presented. Model of the building was made in the Google SketchUp software, while the results of energy performance were obtained using EnergyPlus and jEplus, taking into ac-count the parameters of thermal comfort and climatic data for the area of city of Nis. Obtained results showed that, for varied parameters, the maximum difference in annual heating energy is 15129.4 kWh, i. e per m2 27.75 kWh/m2, while the maximum difference in annual cooling energy is 14356.1 kWh, i. e per m2 26.33 kWh/m2. Considering that differences in energy consumption are significant, analysis of these parameters in the early stage of design process can affect on increase of building energy efficiency.

scholarly journals Energy-Pile Model Verification

2020 ◽  
Author(s):  
Ondřej Šikula ◽  
◽  
Richard Slávik ◽  
Jan Eliáš ◽  
Jakub Oravec ◽  
...  
Keyword(s):  
Heat Conduction ◽  
Low Cost ◽  
Energy Performance ◽  
Model Verification ◽  
Transient Phenomenon ◽  
Conduction Model ◽  
Energy Pile ◽  
Heating And Cooling ◽  
Energy Piles ◽  
Pile Model

Equipping the foundation piles with a liquid circuit pipeline makes it possible to use the advantageous ther-mal capacity of the soil for heating and cooling buildings at low cost. The energy performance of the energy-pile in a soil is a transient phenomenon dependent on many parameters, which could be investigate by a computational model. The contribution deals with the description and verification of a new numerical computational software based on a simplified 2D and 2D rotational symmetrical heat conduction model being developed for energy-piles modeling.

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