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Energy Metrics on historic preservation v. saving energy on Scientific American blog.

Energy Metrics on conservation v. efficiency at Mapawatt

Pingswept writes about an Energy Metrics blower door test.

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Energy Monitoring: An Unexpected Benefit
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Frequently Asked Questions

What is an energy audit?
What is a blower door test?
What is thermal imaging used for?
What is the stack effect?
What are watts abd BTUs?

What is an energy audit?

An energy audit is like a physical for your home or business. Before you can take steps to save energy and make your building more energy efficient, you first need to know where your building currently stands. To diagnose the state of your building's energy usage, we do a variety of tests and cover all the systems that are involved. The end product of an energy audit is a detailed report highlighting the areas of your energy systems that need improvement and cost benefit analysis of each item.

What is a blower door test?

A blower door test is a test that measures the leakiness or air infiltration of your building.  Air infiltration is one of the leading causes of heat loss and also one of the easiest fixes.  The blower door is essentially a fan in one exterior doorway that blows air out of the building.  As the air is sucked out of the building new air is sucked in through all the cracks in the house.  This makes it much easier to identify the leaky areas, while giving you a benchmark of the overall leakiness of the building.

What is thermal imaging used for?

A thermal imaging camera or IR camera is used to show where a building is loosing heat (or gaining heat in the summer).   The camera shows an image of the target with color differences based on the temperature of the surfaces.  If there is air infiltrating an exterior wall or if a wall is lacking insulation, the camera will be able to detect it, since those areas are cold spots.  In the picture to the right, the red line to the left of the window indicates that heat is being lost in this area.  This is a very useful test because it finds areas of infiltration or areas lacking insulation that you would not see with the naked eye.

What is the stack effect?

The stack effect is simply the upward movement of air in your building due to the fact that hot air rises. Hot air is less dense than cool air which means it weighs less and isn't pulled down as much by gravity. This means that hot air will rise to the highest point in your building. As it rises a negative pressure is created in the void where the hot air used to be, and cold air from the outside is then sucked in to fill the void. To minimize the effects of the stack effect you should air seal the basement and attic as much as possible.

What are Watts and BTUs?

Watts and BTUs are measures of power and energy respectively. Power is simply the rate at which energy is expended. For example, a 100 watt lightbulb used for 1 hour has used 1 watt-hour of energy. This can be converted to BTUs by multiplying by 3.41, so that same light bulb has used 341 BTUs.