Influence of Thermal Insulation on the Energy Balance for Cold-Formed Buildings

Abstract

Two major factors contribute to the sustainability of buildings: material efficiency and energy efficiency. Material efficiency relates to the use of environmental-friendly materials and to the minimization of construction waste materials, either during construction and at the end-of-life stage of the building. Energy efficiency is currently understood as the optimization of the energy used during the operation stage of the building. This entails the energy needed for heating, cooling, lighting, etc. Often in order to improve the energy needs of a building, more insulation material is used, thus leading to a trade-off between embodied energy and operational energy. It is the aim of this paper to analyse and discuss the balance between the embodied energy and the operational energy for various levels of insulation, over its life cycle. The operational energy is estimated based on the simplified approach provided by the Portuguese Code of practice. The estimated operational energy is then balanced against the life cycle embodied energy of the system. Finally, the simplified approach for the calculation of the operational energy is confronted to more sophisticated dynamic simulations using the software EnergyPlus.Keywords: Energy efficiency, Light steel residential buildings, Thermal insulation, Life-cycle energy analysis, Embodied energy, Operational energy INTRODUCTIONBuildings are one of the major concerns regarding the sustainability of our habitat. The construction industry consumes materials and energy and is one of the main causes of pollution and resource depletion. According to the EU Communication "Towards a thematic strategy on the urban environment" (…)"The construction sector is of vital importance in our society and is a major contributor to socio-economic development in every country.As the largest and most fragmented industry, the construction sector faces huge challenges in the pursuit of sustainability. Sustainable construction is a way for the industry to move towards achieving sustainable development, taking into account environmental, socio-economic and cultural issues. Sustainable construction ensures more economical use of finite raw materials and reduces and above all prevents the accumulation of pollutants and waste over the complete cycle of the building. Therefore, the use of environmentally friendly materials, cleaner construction

The Effectiveness of Thermal Insulation in Lightweight Steel-Framed Walls with Respect to Its Position

“…When submitted the same model under the EN ISO 6946 [15] analytic calculation method, according to expressions (4) and (10), the same U-value (0.2222 W·m −2 ·K −1 ) was obtained. This second verification confirms the accuracy of this FEM software in performing thermal analysis.…”

“…According to Gervásio et al [4] two major factors contribute to the sustainability in building sector: material efficiency and energy efficiency. The same author also refers that often, to reduce operational energy needs of a building, more insulation material is used, leading to a trade-off between embodied and operational energy, which must be considered.…”

“…Gervásio et al [4] performed a parametric study to analyse the influence of insulation on the energy balance for an LSF building located in Portugal (mainland). This study shows that decreasing the insulation in: 30 mm of polystyrene to 0 mm and 140 mm of rock wool (RW) to 70 mm, in the exterior walls; 140 mm of RW to 70 mm in the roof and terrace-increases by 22.7% the annual energy needs of the building.…”

Energy efficiency and thermal performance of lightweight steel-framed (LSF) construction: A review

“…However, the assessment of the economic and environmental benefits of thermal insulation is a challenging task. Gervásio et al [57] evaluated the influence of several levels of insulation on the energy balance of LSF buildings. The authors also discussed the balance between embodied and operational energies for different scenarios.…”

“…For instance, Thormark [226] showed that about 40-60% of the life cycle energy of a building is used in the initial stages of material production and construction. In a parametric study carried out by Gervásio et al [57] on a LSF residential building located in Portugal, different levels of insulation were considered to assess the trade-off between energy efficiency and life cycle embodied energy. In this study, it was showed that 16 years were needed for the operational energy to overcome the embodied energy.…”