Building Science
Oil production in the Middle East proved to be too much for the United States in the 1970’s. US oil had peaked and resulted in an energy crisis that started to worry people about energy efficiency. This energy crisis changed the way people viewed building construction methods. Being more efficient was a number one priority. Tighter construction standards, increased insulation, reduced ventilation regulation, and more efficient systems were top priorities for the abrupt modifications of building construction methods (Dagostino and Wujek 53). These priorities, however, only generated complaints. Poor indoor air quality, sick building syndrome, and thermal discomfort were initiatives to start the study of building dynamics and how they work together. “Building Science is the study of building dynamics and the functional relationships between a building’s components, equipment, and systems, and the effects associated with occupancy and operation, and the outdoor environment to understand and prevent problems related to building design, construction, and operation” (Dagostino and Wujek 53). The concepts of building science and their relationship to electrical and mechanical systems include the building envelope, indoor air, moisture dynamics, ventilation, and thermal insulation.
The building envelopes primary function is to separate the interior environment from the exterior environment to enhance energy efficiency inside the building. The envelope consists of floor systems, foundation wall systems, above grade wall systems, windows and doors, and the roof system (Straube, The Building Enclosure 2). All of these components have to work together to ensure a healthy environment inside. If the envelope is too tight, then indoor air quality and ventilation will be poor, but if the envelope is too loose, then infiltration will be a major problem. Designers cannot only rely on constructing the envelope perfectly. The external environment plays a huge role. Buildings far north are going to have be designed and built differently than buildings in the warmer south. The local climate and weather provide the major exterior loadings (Straube, The Building Enclosure 4). Designers need to have knowledge of both average and extreme conditions in that area. “Because of rapidly changing materials, building techniques and equipment, the ability to predict the performance of buildings has become much more important” (Straube, Historical Development of the Building Enclosure 7).
Indoor air quality is another important aspect of building science. Occupants of a building must live in a safe and healthy environment, and without good indoor air quality it cannot happen. Studies show that people spend as much as 90% of their time indoors, which 70% of it is inside their homes (Dagostino and Wujek 70). Building envelopes are being built tighter and tighter nowadays. From an energy savings standpoint, it is a good thing, but from a health standpoint, it is fairly dangerous. Having a tight envelope stops fresh/clean outdoor air from entering the building, causing the occupants to breathe dust particles, bacteria, fungus, and chemical vapors that exist inside. “According to the U.S. EPA, poor quality of indoor air is the third leading cause of death and claims an estimated 335,000 lives per year” (Dagostino and Wujek 70). On the other hand, air flow through the enclosure can carry exhaust gases and dirty outdoor air if the building is located by factories. Making sure that a high efficiency and high quality ventilation system is installed in the residence can help ventilate the air and improve the indoor air quality. These high efficiency systems can bring in fresh air from the outside and cycle the older air out of the enclosure by fans and blowers. However, if too much air is removed from the building itself, a negative pressure occurs. Negative pressures have the potential to cause severe problems. Outdoor air may transport moisture into the enclosure during hot humid outdoor weather conditions, back drafting of combustion appliances can occur, and the efficiency of most air handling devices will decrease (Straube, Air Flow Control in Buildings 7-8). In the end, in order to have a tight building envelope system and quality air, it must be matched by an appropriate ventilation system. This will dilute pollutants, proved fresh air, and control cold weather humidity levels.
Buildings must be ventilated properly in order to satisfy the occupants and have a healthy environment. This goes back to indoor air quality. Ventilation is key to maintaining clean air inside a building and removing excess moisture. The introduction of outside air is necessary to replenish oxygen and remove odors inside of a building. “Ventilation is a combination of processes that results in the supply and removal of air from inside a building” (Dagostino and Wujek 77). Improper ventilation can increase CO2 levels that can cause occupants to be sleepy and not focus on their tasks. There are two types of ventilation. One is natural ventilation and the other is mechanical ventilation. Natural ventilation is pretty much self explanatory. This is when infiltration of outside air through cracks in windows and doors of a building removes the air from the inside, putting new air in. Wind can be a good source for natural ventilation in a building. This process cannot be solely depended on, especially when there are many occupants in one building. Mechanical ventilation is the intentional movement of air from outside a building to the inside (Dagostino and Wujek 77). This is typically a heating and cooling system that utilizes blowers and fans to move air through ductwork. Modern systems use heat exchangers to improve effectiveness by using outgoing exhaust air, which also improves efficiency. Ventilation, no matter if it is natural or mechanical, is key to maintaining occupant health inside of buildings.
Moisture in buildings can be related to most of the building’s problems. Although it is common, too much moisture is what creates the problems. Too much moisture causes deterioration of materials, growth of bacteria, corrosion, and damage to interior finishes that are moisture sensitive (Straube, Moisture and Materials 1). Materials become over saturated when too much moisture is present, thus they begin to “leak” the water and the problems begin. The number of buildings experiencing moisture-related problems has risen sharply over the last decade due to changes in construction techniques. Materials tend to expand when moisture is present. There are three areas that can summarize the cause of moisture problems in buildings. One being highly insulated and sealed cavities that reduce exchange in the assembly, two being lighter construction materials that have less mass to store water and organic materials that are more susceptible to moisture deterioration, and three being improper usage of vapor diffusion retarders and air barriers that trap moisture in by limiting moisture transmission (Dagostino and Wujek 78). To fix these problems, better materials should be used. For example, using a vapor diffusion retarder will significantly help with stopping transmission of water vapor. Understanding how and why moisture interacts with materials is critical to the design, construction, and operation of healthy, durable, and energy efficient buildings.
Naturally, heat flows from warmer space to colder space. This is why heat transfer occurs in building constantly. The three main modes of heat transfer are conduction, convection, and radiation. Thermal insulation reduces heat transfer through a building envelope when installed correctly. It helps reduce energy consumption while increasing comfort and saving money (Dagostino and Wujek 57). Insulation functions by trapping gases, which reduce conduction and convection heat transfer through the material. This is measures by thermal resistance, aka R-Value. Thermal resistance is a measure of the ability of a material to resist heat transfer. The higher the R-value, the better the material is. Insulation materials tend to be low density, for example porous materials with a large proportion of voids filled with air (Straube, Thermal Control in Buildings 3). Installation of insulation is another major factor if it is going to be effective or not. Typically, installation would occur between studs, closest to where heated occupancy space is. The more insulation that is installed does not mean it will stop heat transfer more effectively. Like stated before, insulation works better when gases are trapped in the voids, i.e. air. If an installer starts to stuff a lot of insulation in the same spot, then the air will not be able to get trapped in the voids to effectively work. Thus, taking that high R-value and lowering it substantially. Thermal insulation is an important concept of building science that can really reduce energy costs and reduce heat transfer inside of a building if installed properly.
Building Science is advancing all the time. Because of new construction materials and new building methods that are being introduced every year, the building science experts have to keep up and help out designers with effective means of building new construction. Making sure the occupants are healthy and safe from polluted air and making sure they are comfortable are their number one priorities. The oil crisis should not have been what triggered the study of building dynamics. Realizing that everything has to be more energy efficient and making sure that everything works together to maximize occupant health should have been thought of long ago. The relationships to electrical and mechanical systems of building science, including the building envelope, indoor air, moisture dynamics, ventilation, and thermal insulation have to be taken seriously. It is becoming clear that building designers must have some knowledge of building science and the performance of the building enclosure in order to design better building enclosures and better buildings.

References
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Wujek, Joseph B., and Frank R. Dagostino. Mechanical and Electrical Systems in Architecture,
Engineering, and Construction. 5th ed. Upper Saddle River, NJ: Prentice Hall, 2010.
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