There are three basic areas in which thermal energy building science is involved. These include the mechanical, structural integrity properties of a building and the thermal insulation that are used within the building. The three areas are interrelated and each area addresses a specific problem in building construction. In addition to the area of the building itself there are issues such as windows, doors, skylights, roofing materials and air conditioning systems. Each of these areas require a different type of approach to design for thermal energy.
One of the primary functions of structural engineers in building construction is the assessment and design of thermal insulation. The thermal insulation process begins with determining the physical requirements for building construction. Then these physical requirements are translated into building specifications through the use of engineering building physics. The specifications then influence the thermal quality of the building as well as the design of the thermal envelope – the exterior covering of the building.
As building requirements for thermal energy are understood, building physical requirements can be translated into constructional specifications for materials and equipment. Often, the two cannot be directly translated. However, there are several techniques that engineers use to translate building requirements for thermal energy into the necessary materials and equipment. Once this has been completed, the building is built utilizing the appropriate materials and equipment for the project. The goal of this process is to maximize the effectiveness of the thermal energy of the building while minimizing the cost of construction and maintenance.
In order to understand the relationship between building structure, thermal insulation and building physics, one must first understand the relationship between the various forms of energy and the building envelope. This includes heat, thermal expansion, mechanical energy and electrical energy. Understanding how all of these forms interact with each other and how the building envelope responds to changes in these forms is the core of building engineering. This includes thermal, mechanical, electrical and structural properties of the building envelope and how they change with varying temperatures and conditions.
A building envelope begins to expand towards the heated end of the building and contracts in response to cold air. A thermal envelope also begins to collapse if the thermal energy is not conserved. The relationship between thermal and mechanical properties of thermal insulation is very important when developing these three components of the thermal envelope. These include: permeability, static pressure, and tensile strength. There are many complex calculations and equations that are used in the determination of the permeability of a material envelope. In building construction, it is important to have the correct permeability values to ensure proper insulation is installed.
Thermal energy conversion is very important to building science. The relationship between thermal expansion and heat conduction is called the thermal conductivity of a material. This is measured by the specific heat of the construction material and the total amount of radiant heat absorbed or emitted per square foot. The term “effective” is used because it is possible for materials to be rated as “effective” even when they are poorly insulated or contain non-native elements such as asbestos. The entire building envelope must be thermal insulated, or the building will lose energy.
The third component of building science is known as the thermal energy distribution. This refers to the relationship between temperature and the amount of energy in a building’s cooling air or heat transfer. This is especially important for materials used in construction, because poor thermal distribution can reduce the life of the building.
Thermal energy management is a growing field in building science that has been developed to improve energy efficiency in buildings. A variety of methods are used to control thermal convective heat transfer, attic ventilation, insulation, windows, doors, and other mechanical parts of the building. Building Physics helps to ensure that building envelope conditions are consistent with respect to energy requirements and environmental factors. This helps to make sure that materials are selected so that they do not create any energy loss while maximizing building performance.