Shades of Green: the 1970s vs. the Millennial Generation

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Shades of Green: the 1970s vs. the Millennial Generation

The Millennial generation approaches design from the presumption that central air conditioning is normal and necessary

Posted on Nov 13 2012 by Vera Novak

Recently a friend asked for help in designing an off-grid house. Interestingly, I pulled out the old books from the '70s to show as examples and inspiration. We tagged a combination of ideas: an earth berm house, a passive solar house, an attached greenhouse buffer space, a solar thermal system, and a stack effectAlso referred to as the chimney effect, this is one of three primary forces that drives air leakage in buildings. When warm air is in a column (such as a building), its buoyancy pulls colder air in low in buildings as the buoyant air exerts pressure to escape out the top. The pressure of stack effect is proportional to the height of the column of air and the temperature difference between the air in the column and ambient air. Stack effect is much stronger in cold climates during the heating season than in hot climates during the cooling season. heating/cooling system incorporating a heat sinkWhere heat is dumped by an air conditioner or by a heat pump used in cooling mode; usually the outdoor air or ground. See air-source heat pump and ground-source heat pump. (southern rock exposure) and a cool northern forest glen.

It all seemed so — natural …

Apparently this approach differs greatly from the current focus on technology: low-eLow-emissivity coating. Very thin metallic coating on glass or plastic window glazing that permits most of the sun’s short-wave (light) radiation to enter, while blocking up to 90% of the long-wave (heat) radiation. Low-e coatings boost a window’s R-value and reduce its U-factor. windows, photovoltaic(PV) Generation of electricity directly from sunlight. A photovoltaic cell has no moving parts; electrons are energized by sunlight and result in current flow. panels, energy-saving bulbs, energy-efficient HVAC(Heating, ventilation, and air conditioning). Collectively, the mechanical systems that heat, ventilate, and cool a building..

In the 1970s, many homes lacked central air conditioning

Why the difference? I’m going to give away my age here, but I think there might be a clue in the conditions experienced during our “growing up” years.

The energy-efficiency pioneers of the '70s were raised in a world which was just starting to incorporate central forced air heating and central air conditioning in commercial buildings, but mostly without that buffer of mechanical temperature controls in their homes. They knew summers to be hot and winters to be bone-chilling cold. They experienced humidity, and knew the cooling effects of a light breeze.


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So the “problem” they were solving was the core issue of achieving a more even temperature and humidity to increase the comfort level.

The catalyst which sparked the flurry of home innovation in the 1970s was the OPEC oil crisis, but the '60s generation set the stage, with the interest to go “organic,” to embrace nature, and to do your own thing.

So the '70s energy-efficient designs are innovative and organic; they leverage opportunities offered by natural elements. They are based on building physics, harnessing solar heat, moving air through buffering plenums, shading designs for cooling.

Mechanical heating and cooling systems were then positioned as supplemental, providing the final bit of temperature moderation. And “mechanical” solutions were equally creative in those days, including whole-house fans, solar thermal radiant heat, Trombe walls with fans…

These days, central air conditioning is considered a necessity

But forced air mechanical units essentially trumped all those approaches, and this Millennial Generation approaches design from a different reference point. They start with the presumption that central air HVAC is normal and necessary.

So then the question becomes: how should we produce the electricity to feed this mechanical creature which has a permanent spot in your basement or attic? So we put our efforts into solar panels, windmills, or hydroelectric systems.

And the HVAC monster is not the only electricity-gobbling resident in the household. There are water heaters, refrigerators, coffee makers, microwaves, TVs, radios, hair dryers, hair curlers, hair straighteners ... and a gazillion more gadgets.

In systems-thinking jargon, we would call this an electricity addiction. And the interesting part is that if electricity prices are kept low (either through subsidized coal or subsidized PVPhotovoltaics. Generation of electricity directly from sunlight. A photovoltaic (PV) cell has no moving parts; electrons are energized by sunlight and result in current flow. panels), then it triggers an even greater addiction to electricity.

While I’m not necessarily advocating a return to the cave, this addiction (and new norm) distances the HVAC “solution” even further from the core issue, which is rooted in building physics.

From solar to Architecture 2030

So call me an old geezer looking for some recognition for my craft, or a die-hard granola, but I prefer to bill myself as a systems analyst and root-cause problem solver who thinks we could learn a lot by cruising the second-hand bookstores and picking up the old '70s energy-efficiency solutions.

If the black and white photos make you uncomfortable, you can certainly Photoshop in some color — but I think there is some fundamental knowledge to be gained. And if you prefer to learn online, there is no finer collection of these experienced builders than here at These guys have been experimenting, building, and testing building systems for years. (For example, click here to read an excellent synopsis of the solar-versus-superinsulation lessons from the last 30 years).

Which brings me to Ed Mazria, who I first knew as the author of the landmark book on passive solar building. Now he is best known and the catalyst for the Architecture 2030 movement, bringing together good science, analysis, and problem solving to boldly set the energy bar at the level we need to see to address our climate issues.

Minimizing the need for space conditioning

So what if we were to design with the starting premise of no mechanical assist in dwellings? Afer we've refined the design as best possible, only then would we identify the need for supplemental space conditioning. The energy for this smaller and more targetted heating and cooling equipment can come from the grid, but ultimately, we would “pay” this forward by creating excess energy, cleaning more air than we pollute, harvesting and placing more water than we use.

This goal of becoming energy-neutral might help reassess the need for all the electrical gadgets as well. Combining the knowledge gained through the experimentation of the '70s and '80s, the growing knowledge of building science, and the technology of the Millennium, there is no reason we couldn’t achieve Mazria’s goals and leave our own legacy for our children to build upon.

Vera Novak writes the Eco Build Trends blog and is currently earning her PhD in Construction from Virginia Tech.

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Image Credits:

  1. Spector Associates