Daylight performance assessment of an innovative energy efficient building envelope

Abstract

Buildings are considered to be one of the primary contributors to the socioeconomic development of a country. However, they use a large portion of energy and available natural resources. With the industrialization leading to an increase in urban population, the number of urban buildings which has major effects on energy consumption, has significantly increased. Even with the implementation of energy efficient policies, energy consumption in buildings has regularly grown over the last decades affecting the building's operating cost. For this reason, the construction industry seeks to create a model of sustainable development in buildings which has low environmental impact and high economic and social gains. Currently, most of the world population is gathered in buildings mainly placed in urban areas. Unfortunately, a big part of these buildings are badly constructed without or with unsuitable insulation on the building envelope, and without any heating system. After some decades in use, these buildings suffer from an unacceptable interior living environment due to the unappropriated building envelope solution. This practice causes energy losses through the façades and roofs while producing low interior comfort inside the building, as well as health problems to the occupants. Therefore, nowadays the building industry is concerned with designing new construction solutions with novel components and geometries which are able to face the current energy inefficiency in buildings. The TCP is a novel energy efficient building envelope construction solution which is capable of channeling the sunlight through the opaque part of the walls. Its versatility is based on its capacity for concentrating and scattering daylight into the building¿s interior while achieving energy savings, i.e. reducing dependence on artificial lighting and also improving the occupant¿s interior comfort. The complexity of this novel construction solution comes from the physical behavior and geometry of its components, i.e. the Compound Parabolic Concentrator (CPC) and the Optical Fiber (OF). Currently, there is no software in the market that can simulate the daylight transmission of the CPCs and the OFs. In addition, there are no daylight metrics able to properly assess the daylight performance of the TCP. In this sense, this research considered this TCP innovative to give answers to the aforementioned problems. In fact, the building case study shows how is possible to energy retrofit existing façades and roofs while improving the interior living environment and also reducing the energy consumption of the heating and/or cooling systems. This confirm the need to urge the construction industry to design and develop novel energy efficient construction solutions, e.g. Translucent Concrete Panel (TCP). The TCP has the capability of daylight permeability in an anidolic way through the opaque parts of the exterior façades and roofs. Due to the nature of traditional building materials blocking the passage of natural light, there is a constant requirement of artificial lighting into the building, even during daytime. On the other side, some of the most commonly used daylight metrics are not precise enough in order to assess the daylight performance of the prototype. For this reason, the research has designed new daylight tests adapted to the TCP daylight features in order to evaluate its daylight performance. In fact, this is the first required step for future research lines that will be based on computer simulations that to rapidly assess influential parameters of the novel building envelope in several building sub-systems and systems.