The Effects of Roof and Wall Insulation on the Energy Costs of Low Income Housing in Mexico

Jorge Lucero-Álvarez,Ignacio Martín-Domínguez,Norma Rodríguez-Muñoz

doi:10.3390/su8070590

Abstract

Environmental conditions, such as air temperature and solar radiation, have a complex relationship with the energy requirements for heating and cooling of residential buildings. In this work, a comparative analysis of the insulation methods most commonly applied to low income single-family houses in Mexico is presented, in order to find the most energy-efficient combinations of methods for the various climates in this country. A common kind of building, small houses built with hollow cinder block walls and concrete slab roofs, was analyzed considering three insulation scenarios: walls only, roof only and both. We used dynamic simulation to evaluate energy consumption under the climate conditions found in several Mexican cities. From the energy consumption data and the cost of electricity in Mexico, we calculated net annual energy costs, including both annual energy savings and the annualized cost of the initial investment in better insulation. Results of this analysis show that insulating both roof and walls is most effective in cities with cold winters; insulating just the roof is best for temperate climates; and insulating walls (combined with high-albedo roofs) is most effective for cities with year-long warm weather.

Highlights

One representative study consisted of experimental measurements on scale models of houses in Tucson, Arizona; this study showed that thermal insulation had a greater effect on the models’ cooling loads when their roofs had inadequately low solar reflectance [20]
The most economically-optimal case in our simulation, 50 mm in walls and roofs (ALL50), had a net present value of 80 US$/m2 when we considered the real cost of electricity ($3780 US$/year for the whole building)
This study presents performance simulations of three different scenarios for insulating the walls and roof of a small single-family house, under the climate conditions of six cities in Mexico with very different heating and cooling requirements

Summary

Introduction

Energy use in buildings represents a significant fraction of total energy consumption in industrialized countries. The equivalent fraction for Europe is around 26.8%, implying that energy use in buildings is responsible for a high proportion of the European output of greenhouse gases [2]. In 2014, the residential sector accounted for 22.6% of the total electricity consumption in Mexico. Between 1996 and 2008, the number of homes with air conditioning in Mexico grew at an average rate of 7.5%. In 2008, total electricity consumption for air conditioning in the residential sector was 9.3 TWh, corresponding to 19.6% of the electricity consumption for the entire sector [4]. Air conditioners had the third highest energy consumption among electrical appliances in urban Mexican households between 1996 and 2006, accounting on average for 24% of the energy usage [5]

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Results

Conclusion