Green Homes

Building for the future, today – combining the best of historical wisdom and modern technology.

Add to My MSN

Passive House vs. Passive Solar: A Continuing Discussion

4/15/2014 2:12:00 PM

Tags: ask our experts, green homes, passive house, passive solar, passivhaus

Passive House HomeIn our April/May 2014 issue, we ran Passive House: Beyond Passive Solar in Ask Our Experts, which discussed the differences between passive solar design and Passive House standards. In response, we received a letter from architect Richard Schmidt of San Luis Obispo, Calif., questioning a number of points in the article. We’ve posted his letter below, and we’d like to hear your thoughts as well.

“Your article ‘Passive House: Beyond Passive Solar,’ intended to clear up confusion between ‘Passive House’ and ‘passive solar,’ merely adds to the muddle. The only connection between the two is the word ‘passive.’ The building philosophies behind the two could hardly be more opposite, nor is there, as the title of the article implies, the slightest evolutionary relationship between the two. To state that Passive House is superior to passive solar is just plain nuts. That’s like saying apples are superior to tomatoes — a proposition few MOTHER EARTH NEWS readers would buy.

“One of the problems with current building codes and conventional thinking about what makes an energy-efficient building is the codes’ obsession with energy conservation at the cost of energy generation/collection/conversion. Passive House is code-type energy conservation on steroids — a super-airtight, super-insulated building envelope of industrial materials dominates the process. A Passive House, it is sometimes said, can be heated with a light bulb, which sounds fine until you think about how you get there: petrochemical insulation far beyond what’s probably needed; layer upon layer of petrochemical housewraps, vapor barriers and the like; a house that’s so tight you have to run mechanical ventilation 24/7 to control mold and condensation and keep it pollution-free; and paranoia about energy loss through windows so much that windows are often minimized, creating cave-like interior spaces more suited for spiders than human comfort.

“In fact, contrary to your article’s implication that Passive House is merely a souped-up version of passive solar, many Passive House designs exclude winter sun because the building would overheat if sun were allowed to pour into the interior. To top it off, there are the politics of Passive House: One has to follow a set of one-size-fits-all rules to get ‘certified,’ and the competing Passive House certifying groups can’t even agree on just what that entails. This is a very expensive and highly questionable way to build.

“Your writer dismisses passive solar as ‘popularized in the 1970s’ (1970s? Boo! Hiss! Orange bathroom tile! Old technology!). Actually, passive solar embodies timeless energy principles largely ignored by most building codes and not embodied in Passive House. Until the era of cheap fossil fuel, this was the common way of building in much of the world. Then we forgot it, and now, we’re told by MOTHER EARTH NEWS to do something called ‘Passive House’ instead. That is a mistake in clear thinking.

“All building sites have natural energy flows that can — and should — be captured for use by the buildings we put on them. Passive solar heating and cooling — letting in the sun’s winter warmth, storing some for later, keeping out the sun in summer when we don’t want heat — is one means of tapping these basic energy flows, which we can capitalize on free with good design. In places with sunny winters, why not make capturing this free heating energy — with its added bonus of brightly lit rooms that cheer us during winter’s short days — our top priority? If we ever hope to get off the fossil fuel treadmill, it will be through capturing passive energy flows — passive solar heating, passive ventilation, passive cooling and the like. All of these techniques require some thought about how to design a building — they’re not good add-ons, because buildings need to be sited and configured to make the most of nature’s passive energy flows. We also need to fight to get energy generation given coequal status with energy conservation in building codes to make designing for passive energy conversion routine.

“Passive solar design is timeless design — Passive House, not so much. This sort of super-insulated house may make sense in Arctic-like winter climates, but it makes little sense elsewhere — yet it’s being promoted everywhere. I recently read of an affordable-housing project in Santa Barbara, Calif., being built to Passive House specifications. At that point, it became obvious to me that this specialized building approach is being thoughtlessly applied where it makes no sense. Santa Barbara has perhaps the most benign climate on the face of the Earth — one can leave windows open year-round to enjoy the sunshine and ocean breezes. There’s no need for super-insulated, super-tight Passive House design in such a climate. That suggests this is merely a technology-based fad and not a movement greenies should be promoting.

“Unfortunately, in promoting it, your article leads us away from what we should be doing — the simple capture and use of sun, breezes, light and other natural energies we’ve evolved with to make our homes comfortable, energy-wise, simple and healthy places to live.”

A response from Paul Scheckel, the author of Passive House: Beyond Passive Solar:

"The reader brings up some great points about working with nature in building design. The history of intentional-use passive solar energy is older than the human species, and that story alone would make an excellent feature.

"To be clear, the Passivhaus standard was originally developed in Europe and offered an approach and a set of performance metrics for a relatively narrow range of European climates. As the concept was accepted by other parts of the world, those performance metrics required adjustments. As the reader points out, these adjustments were not easily accepted by the more rigorous defenders of the European Passivhaus standard, and that resulted in some fragmentation among followers. Today, we have the U.S. Passive House Institute (PHIUS) to help navigate the much broader US climate. The article does not specifically promote Passivhaus, PHIUS, or passive solar design, but rather sought to offer some level of understanding between these oft-confused phrases. Further, I didn’t write, reference, or imply anything disparaging about passive solar design or the 1970s.

"Properly adhered to, the PHIUS standard incorporates all the benefits of the best of passive solar design, plus additional science-based efficiency approaches using technology, products and processes to drive a building’s energy consumption to exceptionally low levels. PHIUS offers excellent training and resources to those working towards the PHIUS consultant certification. These resources include information on the environmental impacts of various building materials, such as the global warming potential of materials used in the manufacture and installation of insulation products. The reader is correct in pointing out that some efficient buildings can represent the incorporation of more carbon and chemicals than they may save over their lifetimes. Wise choices and solid information are required, and then further aligned with the local climate and tempered with common sense.

"Passive solar designers of the 1970s were on the cutting edge of building design at that time. Both Passivhaus and “Passive House” represent the equivalent in today’s high-tech, low-energy building design world. It’s not easy, though; we humans learn by experience and we don’t always get it right the first time. We may argue about the details along the way, but we keep trying. The Passive House standard represents a significant stepping stone to energy-neutral buildings that can (if desired) be completely energized by small, onsite renewable energy systems. It’s encouraging to see how the greater awareness of building efficiency has influenced innovation and the evolution of building products. In the long view, these “barn-storming” years of low-energy building design seem to be a required process for us to learn how to make practical, lasting buildings for a carbon-constrained world.

"On a final note, the article takes no jabs at the 1970s. This writer has fond memories of growing up in that decade. The article is merely stating a truth that passive solar design was popularized during that era of high energy prices and the reawakening to the many alternatives to energy gluttony. Gone are the days of throwing energy at a problem to fix it. The future requires creative thinking to bring us intelligent, resilient design on all fronts."

Photo by Rick Pharaoh Photography: A Passive House-certified home in Carmel-by-the-Sea, Calif.

Content Tools

Post a comment below.


10/16/2014 10:27:39 AM
Passive solar design from the 70's was an important evolutionary step and we learned many lessons (including the fact that most attached solar greenhouses, as designed then, were too hot in summer and too cold in winter). However, it is possible to design a passive solar home that is still inefficient, and in most parts of North America, passive solar design is NOT enough in an energy and carbon constrained world, as high cooling and/or heating loads will still lead to high carbon dioxide emissions from fossil fuel use. PassivHaus is a PERFORMANCE standard, not a prescriptive standard, and based on research, certified PassivHaus buildings meet their targets, including no more energy use than 15 kWh/m2=or 1.4 kWh/sf and year for heating and cooling (though with a fair amount of variation around the mean). Any good PassivHaus designer worth her (or his) salt, will use passive solar design as a starting point, as solar gain is part of the required energy modeling. So homes that are " creating cave-like interior spaces" are signs of poor design, not PassivHaus design. PassivHaus buildings have sophisticated systems for ventilating a house when the weather is mild (among PassivHaus experts it is referred to as an "openable window"). However, in climates that get hot or cold, it makes no sense to ventilate without heat recovery during weather extremes. This also ensures high indoor air quality and adequate supply of oxygen, unless many non-ventilated leaky homes that may get too much air when it is cold and windy (i.e. unpleasantly drafty), and not enough when there is no wind and not sufficient temperature differential between indoors and outdoors to ensure adequate air supply. By contrast, PassivHaus provides a constant gentle air-flow during the cooling and heating season.

6/15/2014 6:41:22 AM
I would like to thank Richard Schmidt for his response on the question on Passive Solar vs Passive House. My husband and I build a passive solar house using 'old technology' and couldn't be happier with the results. We looked at the passive haus standard and from our simplistic approach and looking at our budget we decided that simple, less gadgets approach was more in keeping with our life philosophy. The 'free with good design' was exactly what we went with. We hired an architect who went to our building site to pick the perfect elevation and orientation and that was the best money spent on our project. We didn't use infloor heating as that defeats the whole process of using the sun's energy to heat your floors. We also went with earth berming rather than using a mechanical geothermal system. When we have had students out to view our house they want to see the mechanicals and what we have is simply the least amount of expensive, need to repair/fix items in our house. If we could have, by law, gone with a passive ventilation system, we would have. In this case less is more. To view our house on youtube go to Thank you to Mother Earth to bringing the topic back to the surface from 1970's....on a side note I wrote a book from an 'owners' perspective and when it was delivered the library, the librarian said he was so pleased to have an 'updated' version since all his books on passive solar were from the 70's I didn't have the heart to tell him that was the version we were working from in building our house. Have a great day, Tracey Allen Author of Building a Passive Solar House: My Experience Shared

5/8/2014 12:16:05 AM
Richard Schmidt is right. Buildings need to 'breathe' the way human lungs do, to be fit for occupancy. 10 years in a 1980's 'energy tight' home with formaldehyde fake wood and other petrochemicals causes asthma, allergies, other major health issues. People are suffocating in these buildings. The hay bale method sounds really great.

Subscribe Today!

Pay Now & Save 67% Off the Cover Price

(* indicates a required item)
Canadian subs: 1 year, (includes postage & GST). Foreign subs: 1 year, . U.S. funds.
Canadian Subscribers - Click Here
Non US and Canadian Subscribers - Click Here