You may have heard of the phrase “money is no object.” It is apparently a combination of words reserved for people who also own private islands and have buildings named after them. It is also occasionally thrown around by politicians when they want to protect democracy or get reelected. We have never actually heard it spoken in earnest, but imagine it must sound wonderful.
In our world (and probably in yours) money is often an object. This limitation creates hierarchies of priority in nearly everything we do. For instance, when I go clothing shopping my hierarchy might look like:
1. Will it protect me from the elements?
2. Will it protect others from the sight of my uncovered unmentionables?
3. Will it last more than two or three days out in the real world?
4. Does it appear to have been designed in this decade?
5. Will it make me appear 10 pounds lighter and bring out the blue in my eyes?
Chances are the interference of monetary concern will limit me to something that meets only the first three or four priorities on my hierarchy. The same is even more true when trying to build green homes that people can actually afford. With an unlimited budget we could simply put every single green feature into a home and suffer accusations only for those things we have literally forgotten, but that would require convincing someone at the Pentagon that our homes were integral to the defense of the nation (an unlikely prospect without incorporating a missile or two). With budget limitations we have to organize our green choices into a hierarchy of priorities and then be prepared to defend ourselves when we are accused of being “ungreen” for failing to use that $80k soy-based, energy-producing, polar-bear-coddling ceiling fan.
So, to that end, here is our working hierarchy of green home elements in order of importance with 1 being the most important and 10 being the least (but still pretty darn important):
The most sustainable decision we can make within the confines of our budget isn’t even a structural part of the home. The location in which we choose to build ranks higher than anything we can accomplish with structure or materials. A standard home built in a dense, walkable neighborhood with access to public transit and amenities is going to be inherently “greener” than even a highly rated green home without those locational benefits. If you are going to build green then “location, location, location” is a mantra with a deeper meaning.
For some reason people often seem to want to cut corners on design costs. This could be because it is hard to finance (it is) or because it seems like a lot of money up front (it is), but the benefits of good design will be around a lot longer than the pain one might incur paying for it. All of the details we are going to touch on after this rely on good design to get implemented. We may have high expectations for air sealing and the reduction of thermal bridging, but without proper documentation in the plans it is unlikely to happen. Good design work also saves money in the long term by creating detailed specs to eliminate mistakes and by reducing timely, costly change orders. This design priority includes everyone from architects to consultants.
3. Air Sealing
Insulation is important. We will get to that in a moment, but in energy efficiency terms the tougher job with an even better return is air sealing. If you can’t control the movement of air in and out of your home then all the insulation you can pack in isn’t going to solve your problems. Caulk, glue, tape, foam, air barriers of all shapes and sizes . . . these are your best friends in the fight for efficiency. Proper air sealing can also save you a world of headaches in dealing with moisture. Where there is air, there is water.
4. Insulation & Thermal Bridging
Once we have sealed up the house to prevent the infiltration of air we definitely want to concentrate on our thermal envelope. This means plenty of insulation and a careful eye to prevent thermal bridging. In the best case scenario, we want a continuous thermal barrier around the entire house. At no point should a piece of wood span the full distance between our sheetrock and our sheathing. Concrete should never be allowed to conduct from inside to out. Insulation and air sealing create an interior environment that is easier to condition and to keep that way. This means reduced HVAC and other savings along with that decrease in ongoing energy use.
All this work in creating a tight, well insulated house is for naught without a priority on ventilation. Good ventilation keeps the air fresh inside the home without losing the conditioning. It is important for both indoor air quality and the energy efficiency of the home. We use an ERV from Ultimate Air, but there are plenty of options out there that can mechanically ventilate a home. This ventilation should be as efficient as possible in exchanging the conditioning of your outgoing air with the unconditioned air coming in. It should also provide filtration to increase air quality and the best ones will help control moisture which reduces air conditioning costs.
6. Windows and Doors
We are still on the envelope here. Anyone sensing a theme? Windows and doors are the completion of the tight, insulated envelope that makes the most difference in efficiency for the least investment. Windows are particularly important because they can be designed to allow for additional solar heat gain even while they are keeping the cold out. The best windows offer great air tightness, high insulation values and good solar heat gain coefficients. Finding the balance between cost and performance is the tough part with windows and doors, but their overall importance is obvious.
7. Efficient Mechanicals
All of the priorities above make efficient mechanicals necessary and possible. The high performing envelope we have created in the above steps allows our HVAC system to be significantly smaller and more efficient when sized properly (finding someone to size it properly is a whole other issue). We have gotten to the point where we can provide most of our heating and all of our cooling from split ductless wall units. These are both inexpensive and incredibly efficient. With the reduction in HVAC energy use, hot water would show up as a major energy line item if not addressed. We reduce this energy beast through our solar thermal system which produces 90% of our domestic hot water with only the power of the sun, but there are other efficient options out there including high efficiency boilers and biomass systems. Overall, our mechanicals use far less energy than a standard house and provide a healthier and more comfortable indoor environment.
8. Water Conserving Fixtures and Appliances
The conservation of water is a key green element in a home and one that is fairly easy to address. Low flow fixtures and water conserving appliances can greatly reduce a homes water use as well as the energy bill for heating water for showers, laundry and dish washing. Providing exterior rain barrels can also reduce overall usage for landscape maintenance. Water is set to be a key resource in the future and building a sustainable home means taking that future into account.
9. Smaller, Energy Efficient Appliances
After HVAC and water heating costs have been reduced, the big hog of energy is going to be the appliances. Most appliances available on the market today are actually fairly comparable with appliances of a similar size (as long as they are Energy Star). This is why we try to reduce our appliance size. Smaller appliances, particularly refrigerators, are much more efficient than their larger relatives. This asks occupants to learn to shop for more fresh food and reduce the amount of overall storage they require, but the energy payoffs are actually pretty high.
10. Low VOC Paints and Finishes
Our focus is always on energy efficiency and health when designing green homes. The key health issue in most homes is indoor air quality. So, in addition to running our ERV, we try to be very conscious of the materials and finishes we use in the home. Whenever possible we use paints, finishes and materials that don’t off-gas harmful chemicals into the air of the home. This occasionally requires a little more investment, but we can’t think of a home as green that doesn’t take health into account.
Now, as I mentioned, our goals for our homes are too reach the highest levels of energy efficiency and health. Our priorities are set out to attain those goals. Some people might think of a green home in different terms and their priorities would be somewhat different. For instance, we don’t have recycled materials on this list. While we use such materials when economically possible and offer them as upgrades, we don’t prioritize them. This is because we would rather spend the extra money (often significant) to provide more insulation and better air sealing. We think the impact is higher in efficiency than it is in using a recycled paper counter top (for instance). There are some that might disagree.
There is also a noticeable lack of renewable energy on our list (other than the solar thermal). We think systems like solar PV are a great thing, but we don’t think it makes sense to implement it until you have addressed the other priorities on our list. Because of the reduction in energy use we get from those items on the priority list, a smaller more efficient system can have a bigger impact on the overall use. In other words, we think prioritizing solar PV would be putting the cart before the horse. Along the same lines, we also try to focus on things that would be difficult to retrofit later. It is relatively easy (if expensive) to add solar PV to one of our houses, but not nearly as easy to improve the air sealing or insulation.
As I said before, this is a working list. We are constantly reevaluating our priorities and some of these even shifted around today. Of course, whenever we evaluate anything we want your opinion. So, don’t be shy. Tell us what you think in the comments.