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Passive Solar Design | Green Building Pros and Cons

Green building options

How to Evaluate Green Building Options


There are many options available in the building industry. Green building and upgraded finishes are the current trends. Every decade has had it’s standard finishes from Formica in the 60’s to granite in the 90’s. The trend is that it keeps getting more expensive. Green building is a trend that will continue although I recommend some value analysis when going this route. Other trends include stainless steel appliances, granite counters, steam showers and hard floor surfaces (no carpet). Building has evolved from the cave in incremental steps. 

Why Passive Solar Design

The single best design choice that you can make is a passive solar design. Passive solar means that there are no working parts to provide the benefits. The added comfort and utility savings come from the design of the project. This is an area where an architect experienced in passive solar design can be a real benefit. Passive solar design orients the entire project, if possible, or windows and eaves as a minimum. The greatest benefits from passive solar design come from window placement, eave size, natural ventilation and thermal mass.

Window placement and the size of eaves (building overhangs) can have a huge impact on comfort and efficiency. West facing window with a 1’ eave will have a major effect on the heat gain in a home during the summer and not allow much light in the winter. South facing windows will catch winter light and be shielded during the summer when the sun sets more towards the west. Bigger eaves will not only protect the face of the home from the elements but also block the higher angles of the sun in the summer yet allow the lower angle   from the winter sun in.

Ventilation is achieved by using windows and skylights to create a convection that will pull the cooler air from the windows into the house and let out the warmer air that has risen inside the house. This can be achieved with a skylight or high windows. I witnessed this first hand when repairing a stuck skylight. As soon as I cracked the skylight open the blast of hot air leaving the house was noticeable.

Thermal mass are hard surfaces, usually masonry and concrete that will retain either heat or cold for a long period of time. A tile floor exposed to winter sun will retain the heat late into the day. Conversely, the same floor kept out of the sun in the summer will stay cooler. These surfaces will maintain their heat and affect the house like radiant heat.

Don’t be a leader – Be a follower

Being on the forefront of new trends can be expensive and problematic. I would recommend that you stay in the “proven” section and let others experiment with new products. Over the years I have built with many new technologies from insulated concrete forms to SIPS (structural insulated panels). I have used bamboo flooring and cabinets, LED lighting and more. Some of it is good and some is not. Bamboo floors were all the rage several years ago until two things were discovered. The new growth (sustainable) bamboo was not stable enough for flooring. It was not hard and tended to absorb moisture. Old growth bamboo is the correct product but is not as sustainable and is more expensive. Other improvements like LED lighting are expensive options that will take years to pay back the initial cost. LED lights are so efficient they are difficult to dim.

Lawsuits are common where builders tried the newest, greatest and often less expensive choice. The only test for building products is building with them and seeing the results in 10 or 15 years. I would not use a technology less than 10 years old. There are too many variables in construction including material handling, material storage, installation methods and weather. Many have unintended consequences on the products success or failure. EFIS, an exterior stucco system is a classic example of this, having failed in most installations causing multiple lawsuits.

Green building is a misunderstood term. Creating a philosophy for your project and it’s impact on nature is essential for successfully building green. A mission statement is needed to guide decision making. A friend of mine who is a local green builder has a saying that building really green means not building at all. That is one extreme. Decide upfront what your goals are. If economy in operation of the home: efficient HVAC, water heating, solar electric is your goal you will make decisions based on this criteria. If you are interested in sustainability: using materials with less environmental impact produced close to the site, your decisions will  reflect that. Define your goals.

How to decide

Green products can be broken into two categories. Materials or products that are in themselves sustainable in nature, healthy for workers and gentle on the environment.  Examples of this are the aforementioned bamboo flooring, cotton insulation, low VOC products (paint), straw bales, mud plasters, etc.  These products can, but often do not save money in operation costs of the project rather they are greener materials and products. In many cases these products are more expensive and when factoring in the fuel costs to produce and ship they are not green after all. There is also not the experience base available in local installers. There are tricks to every trade and using these products requires experience. New technologies have steep learning curves. I recommend that you use products or materials where the curve has leveled out and there are many examples of the installation already in the field. In many cases the cost of the product decreases as the popularity increases.

The second category are products that save money over time.  Additional insulation, higher efficiency HVAC, high efficiency light bulbs and triple pane windows are examples of this category.  These items may not be green in themselves but they make the end product more efficient and save energy and cost in the long run. The same principles apply to these products. Take low flow toilets for example. When building codes mandated to toilets to 1.6 gpf (gallon per flush) the initial products were inefficient.  They needed to be flushed 2 or 3 times to function properly. Over time the product has become more efficient and actually works.

A cost / benefit analysis needs to be done before choosing some of these products. They will be more expensive to purchase and possibly install. Costs of traditional products need to be compared to the proposed upgrades. The difference in efficiency or savings is then diveded by the products usefull life. There are many misnomers about energy saving products. Equipment such as solar panels or HVAC equipment do not last forever and decline slightly in efficiency every year. There are also maintenance costs that need to be factored in. Solar systems claim a 25 year life. This is for the panels, and the efficiency declines yearly. The inverter which makes the system work has a much shorter life span.


Additional insulation may cost 2,000- more and give an expected savings of 20- per month.  This translates into 240- per year and the cost would be paid back in 8 years and 3 months. This is projected without a rise in utility costs so the savings could be more. Utility prices do rise over time but you cannot factor this in as it is an unknown and in many cases government regulated. Added insulation is not going to get you a better sales price when you sell, although it may make the house appear more attractive. If you plan on moving in 3-5 years you may loose money by adding insulation. Most building codes currently have efficiency requirements. Meeting the requirements of the code will provide you with an adequate product that is superior to what was being built 10 years ago.

Warranties are important with new technology materials and products. Since many are untested it is important to be secure in your purchase. There are salesman and representatives available for most high end products that you can get involved in your project. They have the knowledge that will help you make your installation a success.