A lot of people (including the authors of this website) are getting really tired of the word “green”. It’s been applied to EVERYTHING from disposable diapers to SUVs and it seems like half the time it has nothing to do with how the thing being described affects the environment. And let’s face it…minimizing environmental impact is what “green” is supposed to be about. But, when it comes to homes, the first thing that a lot of people think of when they think “green” is sexy stuff like solar panels, or ground source heat pumps, or kitchen cabinets made out of sunflower seeds. And, while these things definitely have a place in building responsibly, the essence of a “real” green home is in the unglamorous things like really good air sealing and insulation, making it as small as possible, and heat recovery ventilation. The kind of things that, if done correctly, nobody will ever notice, yet these are the things that make a home truly green.
Minimizing environmental impact
A REAL “green” home is one that does the least harm to the environment THROUGHOUT ITS LIFE. This is key because by far the biggest impact of a building on the environment comes from the energy that is used to heat, cool, and operate it for its entire life. It follows that the most important thing to do to make a home environmentally friendly is to reduce the amount of energy that it consumes. This is variously known as energy conservation, energy efficient building, or high-performance building and is one of the cornerstones of a REAL green home. So you will find that all of the projects described in this website have a strong emphasis on energy conservation. However it is not the only concern as you will see below.
Responsible Building
Another, perhaps better, term than ‘green’ building might be to call it Responsible Building. In other words, creating buildings that respond appropriately to the requirements of the occupants, the site, the community, and the planet. While energy efficiency is a key part of this, it is certainly not the only thing that needs to be considered. Other important considerations that have to be balanced in every decision that is made include:
- Location (minimizing urban sprawl and car driving)
- Keeping things small and simple
- Health and safety
- Durability and moisture management
- Comfort, function, and aesthetics
- Minimizing other environmental impacts
- Value for money
Location
The location of any project can have just as much impact on the environment as its energy efficiency. If you were to build the most sustainable, net-zero energy house ever designed but place it out in the forest somewhere away from essential services, jobs, schools, grocery stores, etc., the people living in it would be forced to drive their cars all the time. The energy that this would consume would totally negate the energy saved in the house itself. Plus you would be negatively impacting the natural habitat (or perhaps it was productive agricultural land) that was there before the house was built.
So for the REAL green home it is highly preferable to choose either an existing house or an infill lot in a well-established neighborhood within walking or biking distance of all the essentials. This reduces urban sprawl, reduces the need to drive, protects natural habitats and agricultural land, and limits the need to build new roads, sewers, power-lines, etc.
K.I.S.S.
For a REAL green home this stands for Keep It Small and Simple. Once you have your home in the right location, the easiest way to reduce its environmental impact is to make it as small and simple as possible. A small, simple building, by its very nature will require less resources, less energy, less money, less of everything, and create less waste, fewer greenhouse gases, and fewer problems for the environment. But that’s not to say that it doesn’t need to be carefully designed and built to meet all the other goals of a REAL green home. One of the big benefits of building small and simple is that it costs less which, hopefully, means that there will be enough money available to pay for essential items (at least in a very cold climate like Montana’s) like high-performance windows, great insulation and air-sealing, super efficient space and water heating equipment, and a small renewable energy system to meet the limited demands of the home.
Health and Safety
The health and safety of the occupants is obviously of prime concern in the design and construction of any home. And today’s building codes do a pretty good job of ensuring that buildings are safe, but they miss out on a couple of key points. They tend to be decades behind when it comes to energy efficiency, they do almost nothing to ensure good indoor air quality in homes, they don’t fully address the issue of combustion appliance safety, and they are pretty weak when it comes to managing the moisture and humidity that can lead to mold and rot in homes. In a REAL green home these things are considered at every stage of the design and construction and the whole house is considered as a system.
A good example is Heat Recovery Ventilation. It is not possible to make an energy efficient home in a climate like Montana’s without making it tightly air-sealed. However, by making a house as air-tight as possible it is quite easy to create serious indoor air-quality and humidity problems. This is sometimes called “Sick Building Syndrome” which is the result of chemicals gases reaching dangerous levels inside buildings due to a lack of ventilation. This could be alleviated by opening windows but in the middle of a Montana winter this is not going to help with either comfort or energy efficiency. So a Heat Recovery Ventilator (or HRV) becomes essential. Put simply, an HRV removes stale, humid air from the home and brings in a constant supply of fresh air. In the process the two air paths cross but don’t mix, so the heat is captured from the outgoing stale air and used to preheat the incoming fresh air. The end result is fresh air and humidity control without heat loss, which means good indoor air quality AND energy efficiency.
Durability and moisture management
Durability is also a key concern in a REAL green home. A building that doesn’t last long or requires a lot of maintenance is going to use a lot more of the planet’s resources in the long run than one that is well made and durable. Apart from the obvious things like floods, earthquakes, and tornadoes, the main thing that causes buildings to fail and fall apart is moisture. This can either be in the form of rain, hail, and snow or in the less obvious form of moisture vapor. And this is where Building Science comes into the picture. Building Science is the study of how heat, air, and water behave in buildings and how to control the behavior of each of these to ensure that buildings are safe, healthy, durable, comfortable, and energy efficient. For example, a building scientist might look at a proposed wall assembly to determine whether or not there is any possibility of water vapor from inside the building reaching a dew point inside the wall and condensing into liquid water. This is extremely important because condensation inside building assemblies can lead to rot, mold, unhealthy air, and buildings that fall apart.
Comfort, function, and aesthetics
While these are typically considered in any building project they are certainly not forgotten in a REAL green home. The difference is that a REAL green home should be comfortable, functional, and beautiful AND energy efficient, healthy, and environmentally friendly. This can be a complex and difficult juggling act and often times it’s best achieved by using what’s called an Integrated Design Process. This type of design involves not only the architect and the owner but also the contractor and any other key people who’s input might be relevant to the outcome. Often this includes an energy efficiency consultant, a structural engineer, a mechanical engineer, a landscape designer, an interior designer, and possibly a plumber, an electrician, a heating contractor, etc, etc. Regardless of who is involved in a particular project, the important thing is that they all work together from the very beginning to ensure that nothing gets overlooked and that the client gets the maximum possible benefit in return for the money they spend. You might also say that the planet gets the least possible harm in return for the resources used.
Minimizing other environmental impacts
This involves considering the resource, air, water, and energy implications of every decision that is made during the design and building of a home. And it often requires complicated value judgements on the part of the decision making team. Is it better to use bamboo flooring that comes from a rapidly renewable resource but has to be transported thousands of miles, or a locally available fir that comes from an old growth forest? Probably neither, so what are the alternatives and which one is best for the planet? There are often thousands of options available for any particular situation and choosing the right one can be a daunting task. But if we consider that all of us are responsible for helping to take care of this planet that we call home then we have to be ready to make these kind of decisions to the best of our knowledge and ability. We will seldom do things perfectly but we will usually do things a lot better than if we were to just carry on with “business as usual”.
A good place to start when looking for guidance is the simple phrase “Reduce, Reuse, Recycle” (and let’s add “Renew“). The thing to remember is that these terms are in order for a reason. REDUCE comes first and, in terms of a REAL green home, this starts with reducing the size and complexity, because this tends to reduce everything else. Then is carries through every decision that has to be made. Can we get the job done by using less? Less materials, less water, less energy, less resources, less waste, and less environmental impact. REUSE comes next because it is the next most important. Can we reuse something that is already available. In the case of a home this can mean anything from choosing to remodel (and thereby reuse) an entire building, to simply picking up and reusing the nails that fall on the floor. RECYCLE is further down the list because every product that gets recycled into another product requires a certain amount of energy, water, transportation, time, and resources to make the transformation and to get it to where you can use it. Recycling is still important but, if you can meet the same objective by reducing or reusing something then it’s probably better. And RENEW can mean a lot of things from using rapidly renewable, natural materials like bamboo, wool, straw, etc. to renewing or restoring natural habitats or water resources around your home.
Value for money
Incorporating all of these things into a home building project is not necessarily cheap but, when looking at the cost of any building system or product it is important to think past the up-front cost and consider both the long-term costs and the value for money. For example: really good, high-performance windows are expensive. There’s no getting around that fact, however, if you look at the long-term costs, you quickly realize that high-performance windows will actually save the home-owner money in the form of reduced utility bills over the long run. And the higher energy prices go in the future, the more money they will save. Then, if you consider the comfort and health benefits of high-performance windows (the temperature of the surface of the glass stays much warmer in the winter so the occupants are much more comfortable and there is much less potential for condensation which can lead to mold in the home) you quickly realize that they are well worth the additional expense. In fact they’re great value for money!
Which brings me back to the K.I.S.S. point. If you keep the building small and simple you can afford to spend the extra for things that help to make a home truly ‘green’.