Power Use and Generation

BIM for Architecture, Engineering, and Construction Curriculum


Improving Power Efficiency

What strategies can be used to reduce the power density of a building?

A wide variety of high-efficiency and Energy Star products are now available that lower energy consumption and reduce the power density.  

For example, much of the power used in a building is consumed by lighting fixtures. Using compact fluorescent lights (CFL), LED lighting, and other high-efficiency fixtures can significantly reduce power use.

Most manufacturers of appliances (for example, washers, dryers, kitchen appliances, furnaces, and air-conditioning systems) as well as equipment (for example, computers, copiers, and media devices) also offer high-efficiency Energy Star versions that reduce consumption. 

Smart power strips are another innovative alternative for reducing energy consumption by cutting power to equipment that is not being actively and reducing parasitic loads.

How do lighting controls and sensors work to reduce energy demand?

Timers and sensors help reduce power consumption by automatically turning off lights when a room is not occupied.

Daylighting sensors can further enhance the savings by making sure that lights are not turned on when the daylighting available is sufficient to meet the needs of users.

How can you encourage a building\u2019s users to become active participants in reducing power demand?

A good first step is creating awareness of the amount of power being consumed and the associated monetary and environmental costs. This can range from simple approaches (for example, reporting monthly usage data) to more sophisticated systems that report real-time power usage (for example, on LCD panels in a lobby).

Once awareness is created, the next step is educating users about easy alternatives that allow them to be part of a savings strategy (for example, turning off lights as they leave a room or turning off computers and monitors when they are out of the office) and reminding them often.

Photovoltaic Generation

Why is payback used as a driving consideration in determining how much photovoltaic panel area to provide? Why not cover the entire available area with panels?

While more power is potentially available by covering the entire area, if the cost of installing those panels exceeds the value of the power generated, that approach would not make economic sense.

Additional panels could be provided to achieve other objectives (for example, lowering the carbon footprint of the building or earning additional LEED points), but doing so would be investing money to meet those goals.

What are the primary factors that determine the payback period for installing photovoltaic panels? How can changes in the values assumed affect the results of our payback analysis?

Two of the critical assumptions in the payback period analysis are the photovoltaic panel efficiency and the cost of electricity supplied by utilities. 

As technology improves and higher-efficiency panels become available at comparable costs, the area of panels required to produce the same amount of power will be reduced. This will lower the overall cost of the system and reduce the payback period.

If the effect of potential increases in the cost of electricity is also considered, the payback period is also likely to be reduced since the money saved through on-site power generation increases.