Building Physics

Building physics is the cornerstone of designing, constructing, and operating high performance buildings, that is, buildings that are durable, comfort, energy efficient, affordable and healthy. To avoid or solve many building problems, a unique mix of heat and mass transfer physics, material science, meteorology, construction technology, human physiology, and engineering analysis and design must be applied. This mix of knowledge and expertise is often called building science. It was initially developed and promoted in Europe (especially Scandinavia) where it is called building physics.

Thermal Control — by BSC — last modified 2007/04/10

The control of heat flow within and through buildings is important to ensure comfort, health, and productivity. Controlling temperatures also has a major impact on durability and the potential for mold growth. Controlling heat flow is of course required to save energy and reduce the environmental impacts of this energy use. Insulations are basic tools for controlling heat flow, but thermal bridging must be understood to limit heat loss through conductive materials and elements in the building enclosure. Assessing interior surface condensation and comfort are dominated by an understanding of surface temperature. Heat flows by many modes, and one of the most important is by air movement. Whether within an air handling unit or through a roof heat transfer by air flow is important. One of the largest sources of energy flows in many buildings is the sun: solar gain through windows dominates the air conditioning loads of commercial buildings, and can be harvested for both space and water heating in carefully designed buildings.

Moisture Control — by BSC — last modified 2007/04/10

Moisture is the primary agent of deterioration in buildings, and hence controlling moisture is crucial to ensuring durability. Moisture is also the most common factor in Indoor Air Quality problems such as mold and odors. The water molecule has many interesting properties that explain its odd behavior and its interaction with materials. Air barriers, vapor barriers, housewraps/WRBs, and capillary breaks are building products and systems whose major function includes moisture control. The required level moisture control, depends on the quantity, phase (liquid, vapor, solid), frequency of the load and the mechanism of movement that must be controlled. The primary sources of moisture: rain and snow, water vapor in the air, ground water, and construction moisture, have different magnitudes and have different significance for different climates, building uses, enclosure types, and materials. Moisture moves by a number of mechanisms: capillary flow, vapor diffusion, air convection, and gravity flow. Each of these mechanisms is driven by different forces and flows at vastly different rates through different materials.

Air Flow Control — by BSC — last modified 2007/04/10

Air movement carries with it humidity, heat, pollutants, and sound. Controlling airflow, across the enclosure, between zones, and from the distribution system to hollow partitions is therefore required to achieve comfortable, healthy, and energy efficient building. Air movement is driven by pressure differences through flow paths: understanding the complex flow paths and dynamic spatially variant pressure field that act within

Climate — by BSC — last modified 2007/04/10

Different climates, and different interior space conditions, require different assemblies, materials, and design strategies. Increasing the complexity for building designers are different wind loads, earthquake risks, wildfire and flood probabilities. With all these factors playing a role in building design, only one thing can be stated with certainty – where you build should matter to how you build.

Acoustics — by BSC — last modified 2007/04/10

Noise control and encouraged aural communications in building spaces are both part of acoustics. The basic physics of sound are simple to understand, but the interaction of sound pressure waves with complex shapes and multi-layer assemblies with openings is more challenging. Noise control is becoming increasingly important in a world in which more high density housing, closer offices spaces, and busier streets and airports are more and more the norm rather than the exception.

Light (ultraviolet radiation) — by BSC — last modified 2007/04/10

Daylight is both good for the soul and saves energy. Uncontrolled solar penetration also results in over heating of building interiors and causes the surface temperature of cladding to shoot up. Ultraviolet radiation is a also major deterioration mechanism for all organic exterior finish materials, both inside and out.