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Introduction
Published in Iosif Marios Scoullos, Assessment of the Fate of Surrogates for Enteric Pathogens Resulting from the Surcharging of Combined Sewer Systems, 2021
Despite the obvious importance of the issue, most studies until now were based on case-specific events, making it very difficult to have a broader understanding of the mechanisms of inactivation of pathogens. Research on rainwater harvesting showed that the microbial communities collected from different roofing materials such as concrete tiles, acrylic-surfaced bituminous membrane, grass, steel, and asphalt fiberglass shingle were not the same as in ambient rainwater and varied depending on the material used (Bae et al., 2019). The effect of pH is presented separately below, but it is important to note that the age of concrete surfaces affects their pH. Carbonation, the process of hydroxide anions of calcium hydroxide being replaced over time by carbonate anions results in the formation of calcium carbonate and decrease of pH (Pade and Guimaraes, 2007).
Cost-based Facility Opportunities
Published in Scott Offermann, Creating a Strategic Energy Reduction Plan, 2020
Energy saving opportunities can be achieved by carefully choosing roofing materials that reduces radiant and convective heat. Some areas that should be considered when upgrading the roof include: Insulation: When specifying or replacing a roof, additional insulation can be placed under the roof membrane or applied to the underside of the roof deck.Radiant Barriers: In addition to traditional insulation, radiant barriers save energy both in the summer and winter by redirecting radiant energy in the facility.Cool Roofing/Solar Reflective Coating: These systems lower heat gain for facilities by reflecting the sun’s radiant energy, saving energy on air-conditioning. Consult roofing professionals to learn if cool roofing is an option for the facility.
Design Process for an Optimized Enclosure
Published in Donald B. Corner, Jan C. Fillinger, Alison G. Kwok, Passive House Details, 2017
Donald B. Corner, Jan C. Fillinger, Alison G. Kwok
Passive house roofs are similar to passive house walls, but face additional structural and hygrothermal challenges. Hot air rises, which drives moisture into roof assemblies in winter. Furthermore, roofs are exposed to the night sky, which, when clear, can have a strong radiant cooling effect. The exterior layers of a roof assembly are, therefore, more prone to condensation than those of walls. As the sheathing layer is often at risk from condensation damage, it is common practice to vent the area beneath it to the outside, so that moisture can be removed. Venting of the roof is also helpful for preventing ice dams in areas of high snowfall, as it tends to cool the exterior of the roof assembly. In mixed and cooling-dominated climates, reflective (“cool”) roofing can be advantageous in reducing cooling demand, as it rejects much of the sun’s heat. Unvented and poorly vented reflective roofs can pose hygrothermal challenges, however, as the drying potential of the sun is greatly reduced.
An evaluation of the retrofit net zero building performances: life cycle energy, emissions and cost
Published in Building Research & Information, 2023
Replacement costs (RCs) are the planned expenditures for major building assemblies and systems (e.g. roofing membrane). Different assemblies have a different service life that is independent from the whole building service life. For example, a roofing system service life is 20–25 years, and a complete replacement is normally needed afterward. If the whole building service life is 60 years, then the roof system needs to be replaced at least once within the 60-year building life span to maintain the required level of insulation and moisture control. RCs are discounted to their present value, prior to the addition of the LCC total, using Equation (1) (Fuller & Petersen, 1995): where d is the discount rate (interest rate), t is the year, and n represents a specific year when the present value is calculated. PV indicates the present value, and F is the future case amount occurring at the end of the year n (Marszal & Heiselberg, 2011). For instance, if the discount rate is 5%, then the present value of $78.35 at the end of the fifth year will be $100. For decision-makers, those two amounts are time equivalent. Therefore, they will not have a preference between $78.35 received today and $100 received at the end of five years. In this study, the replacement frequency for HVAC systems and the water supply system is once during a 40-year life span, window replacement is once per 20 years, and other building components are assumed not to be replaced, with a discount rate of 3%.
A numerical study of cool and green roof strategies on indoor energy saving and outdoor cooling impact at pedestrian level in a hot arid climate
Published in Journal of Building Performance Simulation, 2023
Mohamed H. Elnabawi, Esmail Saber
The impact of applying a roofing material with high reflectivity and emissivity, such as the cool roofs, is not only limited to indoor energy reduction, as it could also effectively improve the outdoor microclimate and reduce urban heat stress (Sinsel et al. 2021a, 2021b). Therefore, to have a comprehensive evaluation of the cool roof, micro-urban modelling was conducted to examine its urban microclimate effect. In the following section, the analysis of the cool roof surface temperature is reported, followed by the cooling effect on pedestrian-level air temperature over the diurnal cycle. ENVI-met’s building properties were adjusted to represent the different roofing scenarios, including the base case, cool roof, green roof, and gravel assembly. All simulations used the same wall material properties as presented in Table 1.
Energy Conservation of Residential Buildings in Extreme Climates with Phase Change Material-Aluminum Radiation Reflector Cool Roof
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2022
Hajiah and Saber (2020) performed the PCM-assisted roofs in Kuwait City. Their study considered three roofing configurations, including reference roof, roof with drywall, and roof with PCM. These roofs are exposed to the climate conditions of Kuwait City. The results have proven that the combination of reflective materials and PCM reduces the energy consumption of roofing systems. A field study by Beemkumar et al. (2021) observed that the roof with PCM showed reduced temperature fluctuations, and the average peak temperature was lowered by 1–2°C than a reference roof. Cool roofs are well known for enhancing human comfort by lowering energy consumption in residential and commercial buildings. Rawat and Singh (2022) studied cool roof energy consumption with several types of roof surface coatings in various climatic zones. The results of this study showed that the median energy-saving benefit of the roof ranges from 15% to 35.7% in various climate zones. Alshuraiaan (2022) analyzed the thermal response of PCM layer in a multilayer building envelope using a computational model. The Optimization analysis showed a reduction of 50% heat flow into the building.