In order to realize the full benefits of environmental comfort and energy efficiency that modernizing offers, contractors should fit their modernization plans to the specific building type that they are working on. Each of these types has its own criteria and demands a different approach.

Engineers have traditionally divided buildings into two categories: those that are internally load dominated and those that are externally load dominated. Internally load dominated buildings are usually large buildings that generate a great deal of heat internally due to an ample amount of occupants, computers or lighting. For this type, external loads such as outside air temperatures are less important. Externally load dominated buildings, on the other hand, are typically smaller in size and have the opposite profile concerning load dynamics. Since there are so many degrees of difference between these two types, however, this rule has limited use. Modernization plans can be assessed more accurately by envisioning six basic building types: the office, the warehouse, the lab, the assembly building, the industrial building and the house. There are countless varieties and hybrids between them, but these six basic types provide a good rule of thumb.

The first of the six building types is the office. Examples of this type encompass many sizes and configurations. What they each have in common is that internal loads – such as lighting loads and occupant loads – dominate their profile, while external loads – such as conduction and infiltration – matter less. With that in mind, quality lighting and controls, mechanical system efficiency and appropriate glazing and shading of windows are the factors to consider as far as maximizing environmental benefits is concerned. Interestingly, as computer and lighting systems advance in regards to their energy efficiency, external loads will become a greater part of the overall load profile. The increased use of natural lighting in a building's design has the same effect.

A second building classification is the warehouse. This type has the distinction of being the most externally load dominated of the building types and, as such, its lighting and comfort levels are generally not as high of a priority. Designers, therefore, have more leeway to use natural ventilation and lighting as low-cost modernization measures.

The third building category, the lab, uses an enormous amount of energy to ventilate the air so that the environment remains safe for its occupants. Because of this, labs fall solidly into the internal load dominated profile. Traditionally, fume hoods have been purchased based on the features they offer without regard to their energy usage. Thus, fume hoods are largely responsible the lab's reputation as a giant energy sucker. Today, investing in quality protective fume hoods is the single most essential measure to improve the lab's environmental efficiency. Quality lighting and equipment are still important factors, however, and should not be ignored.

The fourth type, the assembly building, is designed to hold a large number of people simultaneously. Not surprisingly, occupant loads dominate this type. Since the amount of air people require and the heat they generate are not subject to change, this building type is less likely to evolve over time than any other type. If anything, as lighting and other technologies improve in efficiency, the static occupant load will become an even more dominant factor. Contractors are therefore better off selecting building technologies that provide comfort while using as little energy as possible. CO2 sensors are an example of a technology that does this since they ensure that only the exact amount of ventilation necessary for fresh indoor air is generated.

The fifth type is the industrial building. The largest of the internally load dominated building types, the industrial building is characterized by its incredibly high process loads. An example of this building type is a factory where the process load is so great that the other building loads almost cease to matter. In modernizing the industrial building, much like the warehouse, designers have license to use natural principals to provide the proper level of comfort. In fact, the designer's main concern should be on how to design the building to keep the process loads low.

The final building type is the house. This is usually the smallest of the building types and its most notable attribute is that its loads are almost completely controlled by the external climate. For this reason, any modernization aimed at increasing its environmental efficiency and comfort level should focus on installing quality insulation and minimizing heat loss through seals and caulked areas. Thermal glazing for the windows is also a good idea as is a window design that regulates the effect of radiant heating loads.

It should go without saying that since most buildings take elements from more than one of the basic types, design solutions should not be applied without considering the myriad of factors that will affect the outcome. In short, designers should never impose the burden of one building type on another by using a system that doesn't take their essential differences into account.

Source: How Buildings Behave, Part 1 – Buildings as Species
Jason F. McLennan
Environmental Design & Construction, Jan. 26, 2002
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