Experimental thermal evaluation of building roofs with conventional and reflective coatings

Hernández-Pérez, I.; Xamán, J.; Macías-Melo, E.V.; Aguilar-Castro, K.M.; Zavala-Guillén, I.; Hernández-López, I.; Sima, Elena

doi:10.1016/j.enbuild.2017.09.085

Cited by 65 publications

(24 citation statements)

References 33 publications

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“…A number of other studies have also found that white-roofed houses in the tropics are cooler than other roof colours [14,17,18]. Most of these studies, however, measured surface temperature of the roof or compared indoor temperature in houses with traditional and modern roofs.…”

Section: Discussionmentioning

confidence: 99%

Effect of roof colour on indoor temperature and human comfort levels, with implications for malaria control: a pilot study using experimental houses in rural Gambia

Carrasco-Tenezaca

Jawara

Bradley

et al. 2021

Preprint

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Background In rural sub-Saharan Africa, thatch roofs are being replaced by metal roofs. Metal roofing, however, increases indoor temperatures above human comfort levels, and thus makes it more likely that residents will not use an insecticide-treated bednet (ITN) at night. We assessed whether the colour of a metal roof affects indoor temperature and human comfort. Methods Two identical, experimental houses were constructed with metal roofs in rural Gambia. Roof types were: (1) original bare-metal, (2) painted with red oxide primer or (3) white gloss, to reflect solar radiation. Pairwise comparisons were run in six, five-night blocks during the malaria season 2018. Indoor climate was measured in each house and multivariate analysis used to compare indoor temperatures during the day and night. Results From 21.00 h to 23.59 h, when most residents decide whether to use an ITN or not, the indoor temperature of a house with a bare metal roof was 31.5 ºC (95%CI = 31.2–31.8 ºC), a red roof, 30.3 ºC (95%CI = 30.0-30.6) and a white roof, 29.8 ºC (95%CI = 29.4–30.1). During the same period, red-roofed houses were 1.23 oC cooler (95%CI = 1.22–1.23) and white roofs 1.74 oC cooler (95%CI = 1.70–1.79) than bare-metal roofed houses (p < 0.001). Similar results were found from 00.00 h to 06.00 h. Maximum daily temperatures were 0.93 oC lower in a white-roofed house (95%CI = 0.10–0.30, p < 0.001), but not a red roof (mean maximum temperature difference = 0.44 oC warmer, 95%CI = 0.43–0.45, p = 0.081), compared with the bare-metal roofed houses. Human comfort analysis showed that from 21.00 h to 23.59 h houses with white roofs (comfortable for 87% time) were more comfortable than bare-metal roofed houses (comfortable for 13% time; odds ratio = 43.7, 95%CI:27.5–69.5, p < 0.001). The cost of painting a metal roof white is approximately 31–68 USD. Conclusions Houses with a white roof were consistently cooler and more comfortable than those with a bare metal roof. Painting the roofs of houses white is a cheap way of making a dwelling more comfortable for the occupants and could potentially increase bed-net use in hot humid countries.

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Section: Discussionmentioning

confidence: 99%

Effect of roof colour on indoor temperature and human comfort levels, with implications for malaria control: a pilot study using experimental houses in rural Gambia

Carrasco-Tenezaca

Jawara

Bradley

et al. 2021

Preprint

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“…To validate the numerical code that solves the heat conduction equation, experimental data from previous publication of the author was used [21]. The numerical code was validated for two cases: a conventional gray roof and a white reflective roof.…”

Section: Verification and Validation Of The Numerical Codementioning

confidence: 99%

“…The numerical code was validated for two cases: a conventional gray roof and a white reflective roof. In the experiment performed by Hernández-Pérez et al [21] with two test cells the exterior surface temperature of the roofs was measured every 10 min for five days. Figure 3 shows the temperatures obtained by solving the model and the experimental temperatures.…”

Section: Verification and Validation Of The Numerical Codementioning

confidence: 99%

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Influence of Traditional and Solar Reflective Coatings on the Heat Transfer of Building Roofs in Mexico

Hernández-Pérez¹

2021

Preprint

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Building roofs are sources of unwanted heat for buildings situated in zones with a warm climate. Thus, reflective coatings have emerged as an alternative to reject a significant fraction of solar energy received by roofs. In this research, the thermal behavior of concrete slab-type roofs with traditional and solar reflective coatings was simulated using a computational tool. Weather data from four cities in Mexico with a warm climate were used as boundary conditions. This tool is an in-house code based on the Finite Volume Method developed by the author to perform building components simulations. The code was validated with experimental data from previous work. A series of comparative simulations were developed, taking a gray roof as a control case. The results showed that for the roof without thermal insulation (single roof), the solar reflective coatings reduced the exterior surface between 11 and 16∘C. Consequently, the single roofs’ daily heat gain was reduced by a factor ranging between 41 and 54%. On the other hand, for the insulated roof, the reflective coatings reduced the exterior surface temperature between 17 and 21∘C. At the same time, the daily heat gain of composite roofs was reduced between 37 and 56%.

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“…Many researchers 11–16 have acknowledged the lack of knowledge, experience and best-practice examples as barriers in refurbishment projects. In the context of sustainable development and the need to reduce energy demand, refurbishing the ageing residential buildings constitutes a necessary action.…”

Section: Introductionmentioning

confidence: 99%

Improving energy efficiency of existing residential buildings using effective thermal retrofit of building envelope

Far

2018

Indoor and Built Environment

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Upgrading the energy efficiency of existing buildings is a well-known issue around the globe. Given the very low renewal rate of the building stock, thermal retrofit of the existing buildings seems to be a good solution to improve the environmental performance of the building sector. Several studies have acknowledged the lack of knowledge, experience and best-practice examples as barriers in thermal retrofit of existing buildings. Therefore, this study has focused on developing recommendations on the most effective and feasible retrofitting techniques for existing buildings and performing financial analysis of initial investment vs return based on the quantitative results of the energy modelling. Thermal comfort modelling software FirstRate5 has been used to simulate the annual heating and cooling energy consumption of nine benchmark buildings through a range of retrofitting techniques. Dwellings of varying construction materials including weatherboard, cavity brick and brick veneer have been simulated to improve accuracy. Examining seven different thermal retrofitting options in this study, it has become apparent that there is significant heating and cooling energy reduction, with payback period of less than three years, by implementing two options of the examined retrofitting cases to existing residential dwellings.

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Experimental thermal evaluation of building roofs with conventional and reflective coatings

Cited by 65 publications

References 33 publications

Effect of roof colour on indoor temperature and human comfort levels, with implications for malaria control: a pilot study using experimental houses in rural Gambia

Effect of roof colour on indoor temperature and human comfort levels, with implications for malaria control: a pilot study using experimental houses in rural Gambia

Influence of Traditional and Solar Reflective Coatings on the Heat Transfer of Building Roofs in Mexico

Improving energy efficiency of existing residential buildings using effective thermal retrofit of building envelope

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