Monthly Archives: May 2015

What is an Energy Audit Worth?

Hose and bucketSeveral years ago, I wrote a post about the value of an Energy Audit.

The story behind that audit was one side.  Improved Comfort. This time it is about the other side.  Decreased Cost of Operation.

An home energy audit reviews the ability of your home to retain the heated air from your HVAC System in the winter and the cooled air in the summer. The best metaphor I’ve seen is to compare the Thermal Enclosure to a Bucket of Water. The picture above is a good example.  The hose is like the HVAC System. It fills the house with hot air in the winter and cool air in the summer.  The Bucket allows the conditioned  to leave the home.

The result of the energy audit is to prioritize which holes to fix first, second and third. Some of this is about how big a thermal leak the hole is, and some of this is about cost.

Attics are less costly to insulate than walls.  There is room for more insulation, it is not a lengthy process, and there is nothing like patching holes after you have insulated.

This home had the improvements made as recommended by the audit, in February 2012.  The energy usage for 36 months prior to and now 36 months after the improvements is now available.

The 3 year average for annual energy use before the improvements is 34,972 KWH.

The 3 year average for annual energy use after the improvements is 18,940 KWH.

A decrease of 45% in energy used.  The bills are paid in dollars, so why refer to an energy measure.  Using energy measures means future increases in Utility Rates are not considered.  Will those increases happen?  Yes! Not counting on them is important. Did they happen during this 6 year period.  Yes, several times. So the results are about actual savings.

IMG_1272 copy

Here is Brian, blowing insulation into the walls. The walls before the work started were uninsulated. If this home had been stucco or brick, this step would not have been cost effective.  The material is cellulose, providing an R-13 in the wall. Cellulose is easy to install in this application. This crew had done this many times and the experience is worth a lot.

IMG_1340 copyThe image on the right is the attic. As you can see there is a little insulation in there before work started.  That meant the crew could do the air sealing first.  Fibrous insulation like the rock wool you see, or the cellulose that was added, does not stop air movement.  Warm air from inside easily goes up into the attic and outside. Good crews air seal before they insulate. They are already up there.  A caulking gun is not hard to carry along.  See those wires,  the electrician drilled a one inch hole to put the wire through.  Lots of air leakage.

Here is a picture I took last winter.  New snow the night before  on the roof of this house. Note the hole near the edge of the roof in the snow cover.  That hole in the snow is right over the outside wall and there is a light switch, or outlet on the wall below it.  Air Leak copy


This simple table will keep your home cool

Table 1 Jean-Sébastien Lagrange and Raphaël Ménard with their Zero Energy Furniture Climatic Table.

Consisting simply of a surface and legs, the table is one piece of furniture that has remained largely the same for thousands of years. But now, a French design duo has come up with a way to turn the humble table into a means of climate control that doesn’t use any electricity. Paris-based industrial designer Jean-Sébastien Lagrange teamed up with French engineer Raphaël Ménard to create the Zero Energy Furniture table, also known as the ZEF Climatic Table. The ZEF table looks like any other with a sleek design of a solid plank oak top and angled legs — but it could hold the secret to cutting energy costs by as much as 60%.


Table 2A close up of the ZEF table, which could cut energy needs by as much as 60%.


“We wanted to see if it was possible to address climate and energy issues on a furniture scale,” Lagrange told WIRED.

Beneath the oak table are a series of phase-changing materials (PCMs) placed between the wood and anodized aluminium bottom. The materials soften when the surrounding room reaches around 71 degrees, absorbing the excess heat, and then harden once the temperature dips back below 71 degrees, releasing the trapped heat with the help of the aluminium and causing a noticeable change in the room’s temperature.

Table SpongeThat means the table is essentially working like a “thermal sponge,” as Lagrange and Ménard put it, sucking up excess heat and then releasing it once the room becomes cool enough.

According to the inventors, the table has the potential to reduce heating needs by as much as 60% and cooling demands by as much as 30%, which could save a lot of money as well as energy.

It’s a feat of engineering that makes the most sense in homes that don’t have climate control.

In climates where the temperature can drastically swing from hot to cold in short spans of time, the ZEF Climatic Table is most useful. For example, if a room heats up on a sunny day and then the temperature drops at night, the ZEF table would make the climate in that room more consistent.

The ZEF table works best in rooms that undergo significant temperature changes frequently.

The Full Article on Business Insider Australia


This article is reprinted in part from the above digital source. It was originally from Wired and was brought to my attention by ASHRAE. Phase Change Materials have many applications in heating and cooling. One phase change material everyone uses is water.  At 32°F it changes from solid to liquid or liquid to solid. Of interest to energy efficiency are materials that act in this way around 70°F.