Energy improvements on an older home: where to begin

             Energy improvements on an older home: where to begin

Before the fuel crisis of the 1970s most Americans never thought twice about their home’s energy consumption. Many lived in older homes that had been retrofitted with electricity, indoor plumbing and forced air heating and cooling, and how efficient these systems were was less important than the fact that were simply there. Efficient and installed were synonymous!

The air conditioner brought an explosion of growth to the southern half of the United States that had once been declared “too hot for civilized people” to live year round. These systems were installed in homes that were not designed for such modern equipment and the results were mixed. Basically as long as the system was blowing cool air the house was cool. These homes were just not good at holding the cool air. So let’s discuss a few ways to bring these homes up to reasonable energy consumption levels. 

Below is my priority list, but it is okay to skip around some if you can’t afford the next measure.

1.     Seal all balloon framed walls and attic penetrations (plumbing, wiring, HVAC).

2.     Seal and insulate attic hatch.

3.     Seal and insulate knee walls in attic area.

4.     Insulate attic to R-30.

5.     Seal and insulate all forced air duct work.

6.     Install vapor barrier in crawlspace.

7.     Seal all plumbing and wiring penetrations in crawl space area.

8.     Caulk and weather strip around doors and windows.

9.     Install bath fans and range hood.

I would consider this list of priorities as a baseline before I purchased any type of energy saving appliances. Of course if the appliances or HVAC system need replacing before you complete the list, do so with Energy Star models. 

I would also consider having a blower door test conducted by a qualified individual before attempting any work. By doing this problem areas can be identified and large amounts of air infiltration/exfiltration can be eliminated. It is a good idea to have the testing done by an impartial person and not a company that wants to sell you the improvements.

Kneewalls

Another topic that seems to make most homeowner’s eyes glaze over is kneewalls. Many may not be exactly sure what a knee wall is, or even if their house has any, so first let’s clear that up. Simply put a knee wall is any wall in your home that has living space on one side and attic on the other. It is considered an exterior wall, but really it is even more susceptible to energy loss than other walls. The reason that these walls are so problematic is that when it is 95 degrees outside the home, it is more like 140 degrees in the attic. So how would you like to try to cool your home in 140 degree weather? If your kneewalls are not sealed...you do!

The new energy codes have addressed how to handle kneewalls in new construction, but it is really not being enforced in most areas. It does add a few dollars of cost to a home, but the energy savings/payback is rather fast.  The following is how the new code handles knee walls:

 All attic kneewalls must be insulated and air-sealed. Attic kneewalls may be insulated using R-13+R-5 insulated sheathing, R-15+R-3 insulated sheathing, or R-19 compressed into a 2×6 cavity. The attic-side of the kneewall must have a rigid air barrier (with seams sealed)

The only real difference in how they were handled in the past (wall cavities stuffed with batts) is that they must now have an air barrier (insulation board) covering the batt insulation on the attic side. Think of it this way; what if your home had no siding and only exposed batt insulation on the exterior? Sure there is no wind and rain in the attic, but how much hot or cold air would leak in your home if that was all that was separating you from the outside. The answer is a lot and when you raise that outside temperature to 140 degrees it gets even worse.

The fix is easy and it is do it yourself friendly. The work can be ugly because no one will ever see it but you unless you invite friends to your attic. Simply nail the insulation board to the wall studs with roofing or plastic-cap nails a seal the joints with spray foam. Be sure you get all the way to the bottom because you need to cap off the floor system below.

Homework 2: Duct Sealing

                                        Homework 2: Duct sealing

Since we breezed right through the air sealing mentioned in the previous blog, let’s move on to duct sealing. One of the things that I neglected to mention in the previous post was that some of the processes I am describing for saving energy in your home are based on living in central Georgia. Climates with different humidity levels would certainly be handled somewhat differently, but for duct sealing it’s all one in the same. The more conditioned air you keep in your home and duct system the less your unit will run and the cost to heat and cool will go down.

If you’re anything like me the understanding of how exactly a heat pump air conditions your home is a big mystery. You turn it on, a miracle happens, and cool air comes out of the registers! Really I understand a little more than that, but for duct sealing you don’t need to understand how the magic happens, you simply need the will and a few materials.  A bucket of mastic, 24”zip ties (two for each connection), a razor knife, foil tape (not duct tape!), a bottle of rubbing alcohol and a box of disposable latex gloves. All of which can be purchased for less than $100 at Lowes or Home Depot, but I prefer my local hardware store.

I would be glad to go in great detail about how to seal each and every connection, but really you just remove each connection, clean with alcohol and coat with mastic. If you liked making mud pies as a kid you will have no problem duct sealing. There are some great videos on Youtube.com and wxtvonline.org that will lead you through the process step by step and it is a homeowner friendly job. By sealing your system you will prevent air leakage in to (and out of) your home even when the system is not running.

What you need to think about when doing this job is that the air moving through your duct system is inside the envelope of your home. When you have leaks you are mixing outside (unconditioned) air with the expensive air you have conditioned. When your duct system is in the crawl space you are mixing in damp, potentially moldy air. When it’s in the attic you are mixing in insulation particles and very hot air. And don’t for a minute think this applies only to older homes and systems. 10%-35% leakage in systems that were new or only a few years old is not uncommon; I’ve seen them first hand. To sum it up-If you don’t have mastic on all duct connections you are giving money away! Time to play in the mud!