Heating (and Cooling) Passively When It’s Too Late to Design Your Home for It

One of the more difficult things about taking on a permaculture lifestyle when we already have an established residence is that, because the practice is based on efficient design, many times we having seemingly come to the game too late. Once a brick-and-mortar house is built and our savings are invested, it’s no small task to start renovating it to have a built in grey water system or south-facing aspect. But, that’s not to say nothing can be done.

With December rapidly approaching and temperatures falling here in the States, passive heating is more and more on my mind. I’m acutely aware of how poorly thought through, in terms of energy efficiency, many homes are. Having only recently returned, experiencing my first winter in a while, it’s painfully obvious, in fact, that rarely has any thought at all gone into passive heating. With power—natural gas, coal, oil, nuclear—readily available and reasonably affordable, houses simply haven’t been designed with this kind of efficient in mind for a long time. Economics has played a larger role than practicality.

That said, there are now a growing number of people wanting to live both more cost efficiently and more sustainably, but they are invested in homes not designed for that. For them, it’s important to find their own ways to contribute to and participate in positive lifestyle changes without immediately giving up everything they’ve worked for. They need to retrofit and make the most of what is already in place. Luckily, passive heating, to some degree, is still an option.

Sun-Facing Windows (Courtesy of Lee Bonnifield)

The Sun & Thermal Mass

In terms of passive heat gain, the sun is our most readily available (free and non-pollutant) source, and sun-facing windows are the easiest way to get it. In efficient, permaculture designs, this is accounted for prior to building a home: there are window-to-wall ratios based on latitude for what amount of the sun-facing wall should be window. For homes in which this hasn’t been considered, the next best option is to be aware of which windows are south-facing. In the winter, make sure they aren’t blocked and can let the sun in, and in the summer, shade them so that they keep the heat out.

Dense materials, such as stone, brick, and tile, have good thermal mass. When these materials are exposed to the sun for an extended time, they heat up so that, when the sun isn’t there, they slowly release the heat they’ve absorbed. In permaculture designs for the temperate climate, sun-facing walls are often built with thermal mass in mind. The walls are exposed to heat in the winter and shaded in the summer. To retrofit this into less efficient homes, be aware of tile and concrete floors or brick walls that may already incidentally exist. Otherwise, consider doing a decorative but functional stone covering over an existing internal wall.

Water also has good thermal mass, and many efficient designs include indoor water tanks to provide heat in the winter. Dark, decorative tanks filled with water could definitely be an option for retrofitting, and in the summer time, the water can be removed. Another clever way to get a bit more out of hot water is to delay draining bathtubs, after baths or showers, until the water has cooled. The warm water will heat the air. Lastly, hot water bottles in beds or under blankets can provide nighttime warmth without turning on the heater.

Big Pot of Soup (Courtesy of Cody and Maureen)

Thinking Reduction & Stacking Function

A major efficiency problem with many US homes is that they are massive, and massive spaces take much more energy to heat and cool. For those already in these types of homes, it becomes important to reduce the amount of space that needs to be completely temperature controlled. Close doors to rooms that are seldom use and try relocate most activities to the sun-facing side of the house, which will be passively heated with the sun, as well as from the body heat created by the people in it. Winter is a time to cuddle up. In the summer, open the doors and windows to create cross breezes and cool things down.

We also have to change some old habits to be both comfortable and efficient, and in terms of staying warm, dressing appropriately inside and out is a good step. There’s nothing wrong with wearing a sweater indoors, and a set of flannel pajamas with some slippers is just downright luxurious. T-shirts inside year-round doesn’t have to be a given. What’s more, it’s better to use an extra blanket on the bed at night rather than keep the entire house at the ideal temperature. These are ways we can change our mindset to reduce the amount of energy we consume.

Finally, like with the thermal mass bathwater, there are ways we can stack functions within our homes so that they are providing heat while accomplishing other tasks. For the most part, this involves using our kitchens, namely the stove and, even more so, the oven. Cooking creates a lot of heat, and something like a big pot of soup is good for that, good for the nutrition, and good for warming you from the inside out as well. Firing up the oven on to bake fresh bread, pies, and cookies also radiates extra heat, and after the oven is off, leaving the door open will allow whatever residual heat is left to escape into the living space.

Dodgy Doors (Courtesy of Julian Burgess)

Protection & Addition

Once our heat is coming from passive sources, it’s more immediately important to protect our homes from the outer cold getting in, and proper insulation is a key puzzle piece in this. Ideally, pole-facing walls will have extra insulation. While this might seem a lost cause, putting outside storage on those walls could help (or stacks of straw bales for next year’s garden), as could shade-tolerant, evergreen hedges. The windows (other than sun-facing) should remain covered, either via drawn curtains and/or cardboard boxes taped over them to prevent cold air from outside passing through to the inside. The attic needs adequate insulation, so check out some ecological versions, such as wool, upcycled denim, and recycled paper.

Another principal part of keeping cold air outside and warm air in is addressing any areas that allow in drafts. It’s important to take time to seal any windows that are letting air in, and ideally, an upcoming investment might be adding storm windows or getting double-pane windows, if they aren’t already in play. Doors are a separate issue here, and they can be aided by checking the weather stripping. If drafts seem to enter from the bottom of the door, a bead pillow or rolled up towel can block that. Then, to be really keen, check all HVAC vents and receptacle boxes for cold air leaks. Get the house sealed as much as possible.

Finally, double-entry doorways work wonders for keeping the cold outside and the warm inside. In the case of sun-facing doors, this might come in the form of adding a small attached glasshouse—or sunroom if you like—about this entrance. The glasshouse will help to insulate the actual house from the cold, still allowing the sun in, and it will provide an intermediary between outside and inside. For other entryways, it’s worth considering not using them in the winter, but if necessary, there is the option of adding a small and enclosed coat and shoes passageway on the outside of the door. It’ll help keep snow and mud from tracking in, and again, this area will prevent cold gusts from an unwelcome visit.

My Lovely Wife (Courtesy of My Mama)

Keeping Warm & Staying Cool

While some aspects of these inefficient development designs frustrate me to no end, I also enjoy the thought of somehow finding ways to make them function a little better. They’ll likely never work as well as a design that considered the passive solar heating in the first place, but that doesn’t mean we can’t improve what has already been done. I like to think that, in some way, this kind of rationale provides great opportunity for people to begin their path towards sustainability. Once on that path, I believe most people will discover how rewarding and easy it is to be better to the planet and, ultimately, the people who live on it.

Feature Header: The Sun (Courtesy of MR photography.)

Jonathon Engels

The financially unfortunate combination of travel enthusiast, freelance writer, and vegan gardener, Jonathon Engels whittled and whistled himself into a life that gives him cause to continually scribble about it. He has lived as an expat for over a decade, worked in nearly a dozen countries, and visited dozens of others in the meantime, subjecting the planet to a fiery mix of permaculture, music, and plant-based cooking. More of his work can be found at Jonathon Engels: A Life About.


  1. Hi… Heating/cooling isn’t really any problem here … We live on The Whangaparaoa in NZ.
    I’m interested in finding a way to utilise our waste water. Could you suggest any directions…?




  2. Living in a condo with no sun facing windows, I can still warm my home in the winter by letting in the afternoon sun and keep it cool in the summer with vines and shades. But even more important is tuning to these subtle effects connects me to the world in simple yet powerful ways.

  3. In my home I have a few sun facing windows, too few to warm the rooms they are in. But, I make them work better with two sets of blinds. My summer blinds are white to reflect the light and heat. My winter blinds are dark brown to absorb the heat. It’s not heating the house. But, it helps a little especially when the sun is shining on snow covered ground.

  4. The old farm house with 2×4 walls had no insulation so we piled manure on the outside 3 – 4 feet high. We also did this to chicken coop and barn. If lots of snow came early we would use it too. 5-6 feet covering on the outside sure made it cozier inside. As soon as the Canadian Winter was over and the manure completely thaws out, the manure would have to be removed to the field to prevent rotting.

  5. The windows on the south side of our home are rather small so we have added solar hot air boxes and pipe in warm air – aided by computer fans that draw very little energy. My husband has also tapped into warm attic air through a vent in our kitchen, with a bigger fan drawing the air down. This has helped us stay much warmer on those cold but sunny days.

  6. We added hay bales underneath our porch which extends under our living room floor (part of the house is elevated on piers). This has definitely helped with retaining heat, as our hard wood floor is warmer and the ambient temp is warmer. We are in western NY state where the winters are rough!

  7. “The windows (other than sun-facing) should remain covered, either via drawn curtains and/or cardboard boxes taped over them to prevent cold air from outside passing through to the inside.”

    On one of our windows I’ve copied some friends who have a beautiful window insulation trick for many of their windows. Use a piece of 2 inch thick insulation board; cut it so it nearly fits into a window space, then add a layer of bubble wrap and an outer layer of fabric to make it fit snugly in the window frame. Use aluminum tape to secure the bubble wrap and fabric to the insulation board.

    If you pick the right color and pattern for the fabric, these window blocks will not only add lots of insulation value, they could look like works of art in your windows. And it becomes a daily ritual to take them out of the windows when the sun is shining and to put them back in place as the day draws to a close.

    Warm wishes to all!

  8. We don’t get much sun in the wintertime (Spokane WA USA). However, if there is sun we can actually increase the temperature in our home during a 32F day without any heat except passive solar. The key is a small house with the longer side of the house facing south — and, of course, lots of windows. I’m always amazed at how many in the city keep all south facing windows covered in the wintertime. I suppose that they are concerned that someone will spot all their stuff and steal it. : )

  9. Coming late to comment on this very relevant article.
    I just wanted to add that it took us a while to make expensive investments to insulate, change boilers etc in our home. To begin with, we just insulated the old inefficiant boiler, the doors and windows, with whatever we could get our hands on, changed lighbulbs and so on. We took readings of our gas and electricity consumption every month (we still do). In our second year, we reduced our bills by 1/3, just with these measures ! The third year we made those investements and chopped off another third, and we’ve kept on going ever since. Every bit helps.
    Love all these ideas, and things like the solar hot air boxes (for which efficient designs can be found on the Net) can add home-made efficiency even without south facing windows. If windows are small, solar reflectors are an interesting option, too. But with global warming, passive cooling is becoming just as importnt to us as passive heating !

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