Design of the Building Envelope: A Novel Multi-Objective Approach for the Optimization of Energy Performance and Thermal Comfort

Abstract

According to the increasing worldwide attention to energy and the environmental performance of the building sector, building energy demand should be minimized by considering all energy uses. In this regard, the development of building components characterized by proper values of thermal transmittance, thermal capacity, and radiative properties is a key strategy to reduce the annual energy need for the microclimatic control. However, the design of the thermal characteristics of the building envelope is an arduous task, especially in temperate climates where the energy demands for space heating and cooling are balanced. This study presents a novel methodology for optimizing the thermo-physical properties of the building envelope and its coatings, in terms of thermal resistance, capacity, and radiative characteristics of exposed surfaces. A multi-objective approach is adopted in order to optimize energy performance and thermal comfort. The optimization problem is solved by means of a Genetic Algorithm implemented in MATLAB ® , which is coupled with EnergyPlus for performing dynamic energy simulations. For demonstration, the methodology is applied to a residential building for two different Mediterranean climates: Naples and Istanbul. The results show that for Naples, because of the higher incidence of cooling demand, cool external coatings imply significant energy savings, whereas the OPEN ACCESS Sustainability 2015, 7 10810 insulation of walls should be high but not excessive (no more than 13-14 cm). The importance of high-reflective coating is clear also in colder Mediterranean climates, like Istanbul, although the optimal thicknesses of thermal insulation are higher (around 16-18 cm). In both climates, the thermal envelope should have a significant mass, obtainable by adopting dense and/or thick masonry layers. Globally, a careful design of the thermal envelope is always necessary in order to achieve high-efficiency buildings.

A Simplified Methodology for Evaluating the Impact of Point Thermal Bridges on the High-Energy Performance of a Passive House

“…Neglecting their presence can lead to significant underestimation of actual heat flows, which can account form 5% to almost 20% of total heat flows through the building envelope, depending mostly on the thermal transmittance of the load bearing wall and the ventilation characteristics of the air cavity. Ascione [6] found that, if the thickness of the thermal insulation layer increases, the U-value of the entire wall will not provide the optimal value in some cases that directly depend on climate conditions. In addition, the material of the bearing layer of the external wall, with its significant thermal properties, can be different from the masonry, made of monolithic concrete, which has low thermal properties.…”

“…Ascione [4] learned that thermal bridges can increase the heating demand of buildings by over 20%. This influence depends on weather conditions [5], level of insulation [6], the thermal bridges' construction [7][8][9], the type of building (use and geometry), and the method used to implement its effect within the calculation of the building energy demand [4]. Approaches of thermal bridges in regulation are different in the EPBD context [10].…”

Resource Usage Strategies and Trade-Offs between Cropland Demand, Fossil Fuel Consumption, and Greenhouse Gas Emissions—Building Insulation as an Example

“…Thermal comfort ranges of inhabitants as well can have an important impact [70]. We neglected this due to our assumption that the buildings have the same initial thermal insulation state and are situated in the same climate.…”

Addressing Large-Scale Energy Retrofit of a Building Stock via Representative Building Samples: Public and Private Perspectives

“…Indeed, in order to provide high-efficiency new buildings, it is enough to establish prescriptions concerning minimum energy performance. Conversely, incentives and public funding may be necessary to promote energy efficiency when not mandatory, and thus in case of energy retrofit (or refurbishment) of the existing • in [7] for what concerns the adoption of standard economic indicators to a historical building; • in [8] with reference to a residential case study for what concerns the building shell retrofit; and • in [9] in matter of overall energy refurbishment of a multi-storey building for households by taking into account the building shell and all active energy systems.…”