Growing up in the 70s I remember hearing about conservation, using less, as a way to cut both the amount of energy used and the cost of energy. Conservation was just one of the words I had heard. Energy savings, better efficiency and the implementation of renewable energy sources, also known then as alternative energy sources, were being researched. Solar energy was the big one at the time. More efficient homes were also a big topic with many new designs like the envelope house, or homes partially submerged or well insulated with either a trombe wall or passive solar.
Through the later 70s and into the mid-80s we actually saw a drop in energy use, mostly by cutting wasted energy by building better homes , cars that got more out every gallon of gasoline and improved energy usage in appliances. Then Reagan got elected and he proceeded to undo all the success we had.
One of the first things he did was pull the solar panels off the roof of the White House. He then proceeded to undo all the energy savings we had gained in the previous decade and we saw cars go from being energy efficient to energy hogs in the form of SUV’s. Not only did they use more energy they got larger. Homes got larger too and less energy efficient. It was as if the energy shortages of the 70s never existed or the fact that the U.S. went from a major exporter of energy, oil first, natural gas second, to a major importer. We still have a supply of coal but oil and natural gas are running out and Reagan acted as if it didn’t matter.
In 1989 Amory Lovins of the Rocky Mountain Institute coined the term “negawatt” which meant the watt of energy not used or rather a savings in energy. The negawatt is the idea of reduced energy usage. Today it is seen more as a commodity that can be sold the same as a watt is sold. The idea is that energy that is not used represents not only a savings by someone but reduced pollution that industries finding is hard to become more efficient could use to claim a reduction in their own pollution, namely electric companies.
The true savings lies with someone implementing the energy savings where lasting savings continue after the initial costs have been paid for well into the future especially as the cost of energy goes every skyward.
Around the same time as the idea of the negawatt became known professors Bo Adamson of Lund University in Sweden and Wolfgang Feist from the Institut für Wohnen und Umwelt (Institute for Housing and the Environment) in Germany came up with the idea of the PassivHaus through some research projects starting in 1988. The first Passivhaus residences were built in Darmstadt, Germany in 1990.
The idea of a PassivHaus is very simple. First, you add another pane of window glass for a total of three panes. Then the design of the home or apartment is build in such a way as to reduce escape routes for heat are greatly reduced. The residence is also super-insulated to the point where it becomes sealed as best as it can be from the outside world. Fresh air is pumped into the home via a special duct where indoor air transfers up to 80% of its heat as it leaves to the incoming fresh air to reduce the need to heat the incoming air. The residence then gains most of its heating needs through passive solar, cooking (or appliances), people and pets.
A PassivHaus costs about 15% more and has been shown to be the most efficient home design currently available. In fact a PassivHaus can cut energy usage by 90% which represents a significant savings. The remaining amount can be made up by using Solar or Wind energy making the home no longer dependent on fossil fuels for its energy needs.
Other ideas have also come along that are very similar like the Zero-Energy Building. There is also the concept of home designs where the home itself actually over the course of a year produces more energy than it uses making the home-owner money rather than costing them money.
All these ideas are not new. Passive solar design was well know for thousands of years. Adding insulation to hold the heat in was the idea behind sealing the cracks to cut down on drafts of earlier home designs and later adding drapery to cut heat transfer to the outside was also used. It was the Romans who added pane glass to take advantage of solar gain during the daytime.
The idea of making a home more energy efficient has only grown but lags behind in the U.S. which continues to act as if there is nothing to worry about believing we still have huge quantities of energy at our disposal.
To tie this to the greenhouse, the old designs were all about glass virtually from ground to the roof-top. These were very inefficient and often only a single pane of glass. In the 1970s some of the first passive solar greenhouses were designed. They often only had glass on the south side, never on the north. Some were sucken into the ground while others were above ground. The angle of the south facing glass was also different as it made the best use of the winter angle of the sun, lower than in the summer months. Combined it made better use of capturing the available sunlight to warm the greenhouse when it was needed and used natural draft to remove excess heat in the summer. They also made use of heat storage in drums filled with water or in massive stone works. Some would even pump warm air underground into a bed of large stones to help hold the heat.
These designs have changed little, it has been namely technology has created better windows and materials for insulation, everything else is still the same. Also, the bed of rocks below ground have been replaced with a what is now called a heat battery where a series of pipes run underground transferring heat to the surrounding ground to help even out the temperature throughout the day time and night time.
Being more efficient in our energy use will go a long way to keeping us comfortable in the future.