Passive Design

BIM for Architecture, Engineering, and Construction Curriculum


Building Orientation

What measures does Ecotect Analysis evaluate to determine the optimum building orientation?

Ecotect Analysis helps evaluate the effects of solar radiation passing through the building envelope (walls, windows, and roof). During colder months, this solar radiation has a positive effect by heating the building and helping maintain a comfortable temperature inside. During warmer months, this solar radiation can have negative effects by adding to the loads on the cooling system. Ecotect Analysis tries to find the optimum balance between these two effects.

Does Green Building Studio consider the same measures?

Green Building Studio uses a similar analysis, but reports the results in a different way. It factors in the local cost of fuel and electricity for the project location and reports the total energy use (and the breakdown of fuel versus electricity used) as well as the costs to supply that energy. Rather than recommending a single optimum building orientation, Green Building Studio enables you to compare many design alternatives to help you choose a preferred alternative.

Why does the optimum building orientation change based on the project location and local climate conditions?

Changing the project location can have a big impact on the position of the sun in the sky, the outdoor temperature profiles that apply throughout the year, and the local cost of fuel and electricity. All of these factors are inputs to the analysis, so the optimum building orientation and estimated energy use can vary greatly based on location.

Building Mass and Shape

How does changing the building shape and massing affect the estimate of total energy used and the distribution between fuel and electricity consumed?

Changing the building shape typically affects the estimate of the total energy used, but the changes can be subtle and require careful analysis. As the overall building shape changes, the areas of wall surface, roof surface, and window surface are also changing. Thus, differences in the thermal properties of these surfaces often confound the comparisons. 

Long, linear buildings with lots of surface area are typically more costly to heat and cool, but also provide more opportunities for natural daylighting that can reduce electricity use. Conversely, compact, multistory buildings have less surface area so they are typically less expensive to heat and cool but consume more electricity for lighting the interior spaces.

Does changing the project location affect the best building shape?

Comparisons between building shapes can be greatly affected by the local climate conditions and energy costs for different project locations. In extreme climates (either very hot or very cold), the effect of the amount of surface area on energy consumed for heating and cooling is amplified.

Window Placement, Roof Overhangs, and Shading Features<\/h3>\n

How would your strategy for placing windows and designing shading features change based on local climate conditions?

While adding windows can greatly improve the daylighting available, they must be placed carefully to maximize (or minimize) the effects of the sun, depending on the local climate conditions.

In colder climates, windows are often placed on the south side of a building to capture solar energy during colder times of the year, and then shading features are added to the windows or roof to block that solar energy when it is not needed or will add to the cooling load.

In warmer climates, it may be desirable to place windows on the east or north sides of a building to provide daylight while avoiding direct solar energy gains during the warmest times of the day. 

The design of shading features is also dependent on latitude of the project location as this determines the position of the sun in the sky at different times of the year.

What types of architectural shading features can be used to control sunlight?

Many types of shading features can be used to effectively control sunlight, and they appear in most every architectural style. Some common types include:

  • Arcades
  • Shade structures, awnings, and canopies
  • Brises soleils
  • Trees and natural vegetation