Upgrading an Existing House
If you are undertaking an upgrade or expansion of an existing house, you have many opportunities for improving its efficiency in the process. If you employ the services of an architect and/or a contractor, try to get people who have previous experience with efficient building design and construction. It will save time and frustration.
Another thing to consider is having an energy survey done. For a few hundred dollars the energy specialist will go through the place with a fine-toothed comb and identify those places where you can improve performance most cost effectively.
While your options will vary depending on the nature of the existing house and the upgrades you plan, the first thing to do is review the options listed under Improve Existing – many of those are also applicable as part of an upgrade project.
Additionally, the following are some ideas you might consider:
Heating and Cooling
In our area, heating is usually the biggest energy user in houses. If you are expanding the house (or even if not), you should consider upgrading to a mini-split heat pump. They require only about one-third as much energy as any of the non-heat-pump options for the same amount of heat. Local electric utilities may also have rebate programs to encourage their use.
Depending on the size and configuration of the upgraded house, you may be able to use a single-head ductless version, multiple indoor units, or one ducted unit with short ducts to distribute the air. Any of these options will provide air conditioning, as well as heating in one unit.
If the existing windows are single-pane, have aluminum frames, are sliding types, or are not well sealed to their openings, consider upgrading to at least double pane hinged windows with vinyl or fiberglass frames. The glass should be coated depending on their orientation in the house, and preferably Argon filled.
Double-pane windows have almost triple the heat flow resistance of single pane and triple-pane windows have about one and one-half times the resistance of double pane. Good quality hinged windows have much better air sealing than any of the sliding options.
If the new windows are properly air sealed and caulked at installation, the completed windows will greatly reduce drafts and condensation, as well as lowering the electricity bill.
If your project includes replacing the external wall sheathing, consider using new sheathing with integral foam insulation on the inside. This product, currently available from at least Zip-System®, is available with various thicknesses of foam insulation bonded to the inside. It is a direct replacement for existing shielding and, depending on the insulation thickness, will increase wall thermal resistance by up to R12.5. It has the second advantage of having an air and water barrier bonded to the outside, thereby eliminating the need for house wrap and improving the air sealing of the walls.
Better Air Sealing
New windows and Zip-System® sheathing will both reduce uncontrollable air leaks, but there is a lot more that can be done as part of an upgrade:
Replace the doors with ones that have gasketing on all edges. If that isn’t possible, make sure doors have fresh gasketing and sweeps and are hung straight and true.
Seal around all wall, ceiling, and floor penetrations, inside and out.
Inspect and seal all joints in any ducting that runs through the attic or under raised floors.
If existing exhaust fans are retained, make sure that the dampers above them shut tightly and stay tight when they are not in use.
Heat Recovery Ventilation
If possible, replace existing exhaust fans (except that over a cooktop) with a heat recovery ventilation (HRV) system. If you have an accessible attic, it is relatively simple to remove the existing individual fans and then use the existing grills to route stale air through a centrally-located HRV and out to a single roof jack exhaust vent. Then bring fresh air from outside through the other side of the HRV and supply the air to bedrooms and living spaces. All these ducts need to be well insulated after installation, of course.
The resultant system will significantly reduce the house heating load, and will be much quieter in operation.
If space permits on the south-most side of the house, consider adding a three-season sunroom. Although it will not be usable in the winter, it will provide free heat on sunny cool spring and fall days, and can be configured as a screen room during the warmer summer months.
Insulated Hot Water Pipes
If they aren’t already, add thick insulation around all hot water pipes. They will then lose less heat with the result that less hot water will be required for a shower or bath or a load of dishes.