When it comes to discussing and defining sustainability, there are many points of view. The term "Green" has been so over used by the design profession and the construction industry that it has lost much of its meaning.
The term "Green" is used synonymously with sustainable. There are many published Green rating systems (LEED, Green Globes, National Green Building Standard, Energy Star, Build it Green, and others) used to measure how Green a structure is. They all assign point values to the various areas they feel are important. Based on the points attained, the structure gets a grade, which represents how Green or sustainable the structure is, according to that system. However, there is no rating prerequisite for sustainable design and construction.
My kids have been taught in school to reuse, reduce, and recycle . This is a great start to discussing sustainability. It seems that recycle and reuse get more attention than reduce. This maybe because recycle and reuse are more tangible than reduce.
Reduce. In other words, use only what we need. While reuse and recycle are important, reduce is the most significant and impactful aspect to building sustainably.
While reducing begins physically at the construction site and continues into the operation of the home, its planning begins in design. To really be successful in building a sustainable home, you need to begin planning for it well before construction.
This, however, is where the shades of Green come in. This is not a black and white issue, as many would lead you to believe. Sure, the more Green you can be, the better the earth will likely be for it. But if you can be better educated about the subject, ask questions during design, and choose the Green areas you would like to focus on in your project, it will matter and it will make the earth a better place than if you had simply done nothing at all.
So, what to do.
This is a complex and very technical subject. Many universities offer a doctorate degree in environmental sciences. I would like to keep this discussion straightforward and meaningful; give you some things to think about that will enable you, if you wish to pursue this subject further, to ask meaningful questions of your architect and builder.
If you are building from the ground up and have some flexibility on the orientation and location of the house on the lot, the siting will have a major impact on the energy utilization of the home. The location of the windows and how much sun enters the house will greatly effect the heating/cooling requirements of the house.
The footprint of the house (how much of the house actually touches the ground) will also alter the natural flow of water as well as affect the soil's ability to absorb water. Reducing the footprint promotes water retention on site. There are many things we can live without. Water is not one of them. It is irreplaceable and the most valuable resource on earth.
During construction, while you want to minimize waste, you should also consider material choices that are easy to maintain, durable, and locally sourced. You may want a material or product that is manufactured in Italy, for example, but it is far more efficient choosing a similar material that is manufactured locally. Compare the amount of energy used to transport the same product from Italy versus from your local geographic area.
Consider flexible floor plans. As we age, our needs change. People usually want to stay in their home as they age. Plan for it to happen and you can avoid revisiting these issues later in life.
This philosophy also makes the house more marketable to future buyers. A flexible house will likely appeal to many more buyers. And the new buyers will be less likely to significantly remodel the house as well.
As for heating and cooling (HVAC), have the system properly designed and select the highest efficiency you can afford. While you will never see the heating and cooling system (it is very unlikely that anyone will compliment you on how nice your HVAC systems is), paying for a higher efficiency HVAC system up front will save you much more money in the long run (and it will use much less energy).
Insulate your house better than is required by code. This includes selecting windows with the best insulating values for your given budget. The building codes are simply a minimum level. Achieving the local or state building code is only a "C" grade-passing. Better insulation levels will make the house more comfortable and, again, use less energy (saving you money).
Take care during construction to seal the house. The house should be tight. It should not leak air. If air is freely moving between the inside and outside, you are not only conditioning the outside air, but wasting a lot of energy in doing so. The movement of air, in both directions, also can carry large quantities of water. This water can end up in places that should be kept dry, resulting in rotting materials and possibly affecting the air quality of the home.
Speaking of air quality, this is a relatively new, but significant, issue in construction. Older homes leak great quantities of air. And, thus, they have relatively good air quality because the air is being replaced regularly. In newer, tighter homes, steps must be taken to allow for fresh air to controllably enter the house.
There is an assumption here that I will note, but not dwell on. Your house needs to be designed for the climate where it is located. A house designed for Arizona will be different than Minnesota. There are some construction methodologies that must be followed, based on climatic differences.
The electrical system should use dimmers, occupant sensors, and LED lighting. The house should also be pre-wired for solar power and an electric charging station (for an electric vehicle), as well as pre-plumbed for solar thermal water heating.
Although not discussed nearly as often as they should be, grey water systems, critical in areas that receive low rain fall, are one of the most valuable and impactful water conservation methods. Incorporating a grey water system (or at least pre-plumb) into your project is a great way to conserve this very precious resource.
After you select the systems you wish to employ to reduce, you can then focus on reusing and recycling. Many of the materials that go into construction can either be wholly reused or have a percentage of recycled content. Where possible and when available, it is great to make use of these materials.
To reiterate, however, the building systems (HVAC, plumbing, electrical, insulation) that are not typically seen and contribute no aesthetic value will have the greatest impact and contribute the most to saving energy and water over the life of the house. Most people would rather spend money on quartz counter tops or walnut cabinets than on systems that cannot be seen. It is simply a matter of priorities (unless you have an unlimited budget, you will find that, ultimately, the design and construction of a house is simply a matter of setting priorities).
Many home owners may feel that all of this is beyond their level of expertise. You do not need to fully understand all the technicalities of the issues being presented here. But knowing that these issues exist and should be considered, puts you in the position of asking pertinent questions. It really comes down to how strongly you feel about these issues and how you prioritize them into your project.
Once you decide on their priority, they can then be addressed in more detail. Remember, there are shades of Green. You do not have to employ all of the above strategies. While many would argue that you are not doing enough, a more optimistic view is that you are informed and aware of the issues and that you are, in fact, doing something.
Green building is really just the application of good building principles. You can call it whatever you like. But utilizing strategies that conserve energy and water and result in a more comfortable and healthy indoor environment is just common sense.
Also understand that using a photo-voltaic system (solar power) to lower the cost of electricity does not make the home more energy efficient. You are still using the same amount of energy. It is merely offset by the power generated by the PV system. Solar energy is a great renewable energy source and we should make use of if when possible. But we should focus first on making the house efficient.
Lastly, be aware of Greenwashing.
Anything and everything that goes into the construction of a house is now sold with a tag line that it's sustainable. Can everything be Green? Unfortunately, a plausible argument can usually be made for either side of the Green line.
It is important to keep an open mind and always consider both sides of an argument. Get informed, weigh the consequences, and justify to yourself whether or not you think the viewpoint expressed is logical. While there is definitely a science behind sustainable design and construction, confusion about products or processes can often be resolved by simply applying common sense. Discuss these issues and any questions you may have with your architect.
Ultimately, this is a personal choice that you will make during the planning and design of your home. How sustainable your project is will be based on priorities. Just keep in mind that there are shades of Green.