Energy and Construction - Clima2007

Enrique Said:

Need some advice about brick wall construction and energy efficiency re: a 1910 home...?

We Answered:

With a house as old as the one you are saying, I doubt there is any wood framing in the walls. You should actually look at that as a good thing if you did buy, as it would take away one aspect of potential decay in the structure. It is possible that the exterior brick is only a veneer. This is the term used if a wall system is used to cover the structure and made to look like the actual wall. If the brick on the house is a veneer, there is likely a more strudy block underneath it that is actually bearing the house.

Now it is also completely possible, as you suggested, that the interior brick is the load bearing structure. Now you have to remember when this house was built. Synthetic materails were not a common back in the early 1900's. It is unlikley that the house has insulation in the walls. A common practice of that time was to actually build a double or even triple wythe wall system. A wythe is basically a line of bricks. In a multiple wythe system a wall of bricks is laid, an air space is left, and then another wall is constructed. This achieves a better system of insulation than just one brick wall. It is a similar idea to a double pane window. This form of insulation works pretty well. You will often get better and more consistent insulation from this version then you would from pourly placed synthetic insulation in a modern house.

There are companies you can hire to come out and assess the insulation properties of a building. I would imagine that any energy savings you might find by doing this would quickly be eaten by the costs. The other suggestion I would make is going to the local jurisdiction and obtaining a copy of the plans. I am not sure how large of a town you are in, but assuming the house was in some local jurisdiction when it was built, it probably needed a building permit. This means there should be plans on file (assuming they were not lost, stolen, distroyed, etc.). If there are plans it would show the structure of the walls, and should show the insulation as well. That is your best bet. Good luck.

George Said:

energy efficiency and economic efficiency?

We Answered:

a. no. Economic efficiency is value for money, where value includes not just gas mileage but car design, acceleration, safety, reliability, etc. Money include not just the price of car and gas, but also cost and frequency of maintenance and repairs, interest cost of the car loan, etc.

b. When energy efficient car is as good as conventional cars in all of the criteria described in (a), or at least not much worse.

c. B/c "benefit" is an economic concept, not an engineering one. If the goal is to maximize mpg, you would end up making everybody ride motocycles (unsafe and uncomfortable in rain). If your goal is to minimize gasoline use, then you should ban personal vehicles and replace them with public transport (Soviet Union almost did that)

Geraldine Said:

How would you increase building interior energy efficiency using the same heating and cooling systems?

We Answered:

In most homes, air infiltration is a common problem both in the winter and summer. In addition to the common places such as outside doors and windows, other culprits are chimneys and opening to attic spaces. Pull down stairs for attic spaces is a really big one. All you have to do is take a plastic trash bag and place it horizontally under a pull down stairs and see the result. Conventional doors that lead to stairs and attic spaces are typically no weather stripped and that is also a problem. Chimneys, even those with the dampers closed, are an avenue for a very large amount of heat to escape in the winter.

Large overhangs on exterior walls to keep direct sunlight from the side of buildings is also overlooked in most cases. If you look at many very old houses in the southern US, they have large overhangs or porches on the east and west sides to minimize direct sunlight hitting the walls.

Where buildings have an outside makeup air stream, heat exchangers can be installed to recover some of the interior heat (or cool) from the outside going air.

Lester Said:

What is energy efficiency in building?

We Answered:

Efficiency is basically the amount of useful energy that you get divided by the energy that was put into getting the desired response or output. In a building, it is heated or cooled by using electricity or kW-hr. The heat is also dissipated through heat loss by conduction through walls and mostly windows and doors. Windows and doors are always the biggest heat loss area and ceilings. Ceilings/roofs require the thickess amount of insulation. A typical house requires R-38 insulation in the attic and R-19 to R-21 in a 2x6 wall. The higher the R-value the better. Materials such as fiberglass and foam possess very low thermal conductivity values which mean that less energy will be conducted through an area over time as opposed to something like steel which changes temperatures very quickly. Steel and other metals are said to have higher thermal conductivities. All of these factors are taken into account when designing a bulding to be efficient.

Weather stripping around doors and windows make a larger difference, this allows warm air to escape quicker or warm air to come in from the summer. Warmer air always moves towards colder air, higher energy concentrations always moves towards lower energy concentrations, same thing with concentrations in chemistry and electrical potential in electricity. Current flows from areas of higher voltage to lower voltage. Windows have a u-value and solar transmittance value. This is where radiation comes into play from the sun. Solar radiation is a type of heat energy that is electromagnetic energy that can heat a solid or medium without air. Radiation can exist in a vacuum in other words, the absence of air. This is how the sun heats the earth through space to the earth which the existence of air.

Convection is another method of heat transfer, when the wind blows on a 15 deg. Fahrenheit day, it has a higher convection coefficient and removes more heat energy that has conducted through the walls of a building. These three types of heat energy all have to be taken into account in designing an energy efficient building in terms of heat. If you notice, baseboard heaters are always placed in front of windows because windows lose a lot of heat. Baseboard heaters are also placed along the ground since hot air rises and cooling vents are placed in the ceiling because it will sink down due to the higher density than the ambient warmer air and it will promote better circulation. Hope this helps.

Bobbie Said:

Which is more energy efficient, vents closer to outside walls or closer to the middle of house?

We Answered:

Depends on which vents you are talking about. Generally cold air returns are on interior walls while supply registers are on outside walls.

Marion Said:

What's the best power supply that has the best energy efficiency?

We Answered:

Well you will want a lot of power then. Check these out. 80+% efficiency.

Eduardo Said:

Is there a tax credit for insulating a business office (Energy Efficiency Credit)?

We Answered:

Yes.

Taxpayers may expense the cost of energy efficient commercial building property placed in service in calendar years 2006 or 2007. The deduction for any building for any tax year can't be more than the excess if any of
1. $1.80 x the square footage of the building and the
2. deductions allowed under sec. 179 depreciation deductions for earlier years.

Energy efficient commercial building property is property that
1. is depreciable or amortizable
2. installed on or in a building located in the US
3. certified as being installed as part of a plan that will meet a 50% energy use reduction test described in code sec. 179D(c). In some situations where the 50% test isn't satisfied, a partial deduction may be permitted.