Keep your mid-century house cool with passive solar

40 min readPassive solar design has been around since forever. It just means that a builder makes siting and design choices that use the sun and shade to keep a building warm or cool.

Your mid-century house might be blessed with a great passive solar design or it might have a wall glass facing full west. If you know, you know!

For anyone in the later situation you may be looking for some mcm appropriate ways to shade your over-sunny living room in the evenings or to let a little more light into a shade-locked space! With a smart remodel, you can!

If you can set up your remodel plans to IMPROVE the passive solar potential of your home while also jazzing up it’s looks and streamlining the flow … you’ve got a win win win!

First …

What even is Passive Solar design?

The easiest way to think of it is using common sense to let sun into the house (when you want it to be warmer) and keep it out (when you want it to stay cooler). In the summer Passive Solar design is all about shade strategies. In the winter, it’s about good insulation and letting sun shine on surfaces with enough mass to heat up and then stay warm for a while.

With the right orientation and roof overhangs you can get sun in the winter (when you want it) and keep your living spaces shady all summer. This Indiana home came with a wonderfully shady breezeway (partly screened) between house and garage to make the most of summer shade.

Basic Passive Solar Design Principles

Good daylight design is about more than adding shade cloth and cutting holes for extra windows.  You’ll want to consider orientation of the building, wall-to-window ratio, window placement/shape, and exterior shading devices.  Think about how letting in light will affect the heating and cooling load and the insulation of the thermal envelope.

Light from the…

  • North is best for even, indirect light. It doesn’t create harsh glare or shadows and is preferred by artists. 
  • East is morning light, think sunrises (and moon rises). This light can warm a house after a cool night but poses no threat of overheating in the summer. 
  • South can run the risk of overheating and glare. However, it is relatively easy to control with well calculated shading devices like roof overhangs and awnings.
  • West is low slanting sunset light, especially in the late summer, can add unpleasant glare and a lot of heat. This is the most important light to control with shading from trees or adjacent structures.

Passive solar for different climate zones

For buildings in hot climate it’s most important to focus on indirect light sources (north and east) while keeping any heat gain out of the building.  Choosing the necessary windows to minimize solar heat gain can also help keep unwanted heat out of building.

Many California homes have deep and shady eaves which keep the sun off their exterior walls and protect their big windows from overheating. This client’s side yard was wonderfully shady from the start!

In a cool climate, however, direct light can be harnessed as a home heat source, through passive solar design.  Buildings with a south facing aspect can let winter sunshine shine in onto a thermal mass – a surface that will slowly absorb the heat of the sun and then release it slowly after the sunlight has gone – like a concrete floor or stone wall.  

A well insulated building (capable of holding onto that heat) with good ventilation (to let out extra heat if necessary) can offset some or even all of its heating needs on sunny days.

Passive solar is too unpredictable to be your sole heat source – it can’t replace your furnace entirely – but it can seriously offset artificial heat sources under the right conditions.

Taking advantage of stack ventilation will help your building cool itself; by making a pathway for hot air to escape from the top, cool air will be drawn in from lower windows and create a breeze.  

You can also plant trees – or take advantage of existing trees – for shade as well as working with existing buildings to block out that harshest, hottest, western light.  Deciduous trees to the south block heat in summer and let in winter light.

You may want to pair tree shade with a trellis structure to ‘define’ the space of your outdoor rooms.  

When all else fails, turn to window treatments. Judicious use of shades can block, or diffuse, natural light making it work for you not against you.

No time to wait for trees? Make your own shade with inexpensive shade sails that you can put up each summer and take down in the winter to control light and heat.

Who invented Passive Solar design?

Passive solar design REALLY has been around since forever.

(This is a place where I’m going to talk a little bit about vernacular architecture. Although the term “vernacular” itself is actually pretty snotty. It’s the kind of word that’s used by people who consider themselves to be experts when they refer to the good ideas of people they don’t consider to be expert as surprisingly smart, and then steal them.)

Google it and you’ll find something like:

a style designed based on local needs, availability of construction materials, and reflecting local traditions. A style not using formally schooled architects for design, but relying on the skills and tradition of local builders.

Basically, it just means the common sense choices that respond to environmental conditions of the people, wherever they are. 

Why don’t we still design with passive solar?

So if literally everybody used to know better, why don’t we design houses with passive solar now?

Well, this is just one more way that industrialization, capitalism, western society, generally has detached us from some of the practical solutions that were used in the past.   

As people and buildings were grouped together in larger clusters, and looked after my larger and larger, civic organizations move away from things like everyone getting to fight a house in a place that makes sense increasing and direction that makes sense. 

Instead, we start drawing lines on maps arranging streets of grids. The original concept of an urban plan being a grid goes back to the Romans. They liked the idea that their military and police force could stand at one corner and see a long way in multiple directions and run straight to a problem. 

Eventually, we just get into the habit of planning out a development on a map first. Dropping in a grid and directions seems useful. As did organizing our streets to be easily accessible by car.  And then popping houses along them one after another with the front door facing the street regardless of the direction. 

When you have a house with a really tricky solar site – harsh west facing sun heating up a space like this patio – overhead shade won’t cut it. You may need a combination of overhead shade and vertical shade curtains or sails to keep low angled evening light from overheating your space.

In Today’s Episode You’ll Hear:

  • Why we stopped using passive solar design. 
  • How to get big wins from small changes. 
  • Key principles you can use right now to cool your home with less energy. 

Listen Now On 

Apple | Spotify | YouTube

Quick design tip for…integrating passive solar design

Incorporating passive solar techniques isn’t an afterthought – it’s an integral part of your design thinking! Planning for passive solar techniques is part of the Master Plan process. Any change to your layout presents an opportunity to improve airflow, enhance privacy or connection within your family, and optimize your home’s relationship with the sun. Often, a single design move can yield multiple benefits.

Mid Mod House Feature of the Week

louvered windows (also sometimes called jalousie windows).

These windows, with their adjustable glass or wooden slats, offer a unique way to control airflow and light. You can angle the louvers to allow breezes in while still maintaining some privacy and even keeping out light rain.

The combination of a louver vent window with a fixed glass system, which seems to have been innovated by Keck and Keck, is a particularly brilliant design. It allows for both ventilation and an uninterrupted view.

Resources 

And you can always…

Read the Full Episode Transcript

Let’s talk about how to make your house look cool and also be cool, because summer is around the corner and you may have already had to dust off and turn on your AC. In my opinion, the nicest days are the ones where I can keep the house pleasantly cool and breezy without having to listen to a big fan and use up nonrenewable resources. I do this by opening and closing the windows at the right times, adjusting the curtains and shades, leaning into the shade provided by the trees around my house, and augmenting it with a shade cloth that also defines my patio. You can do the same.

All of these passive solar cooling techniques are available to you and can be paired with improvements to the way it feels to live in and around your house, and perhaps even upping your curb appeal potential. Hey there. Welcome back to mid mod remodel. This is a show about updating MCM homes, helping you match a mid-century home to your modern life. I’m your host, Della Hansmann, architect and mid-century ranch enthusiast. You’re listening to Episode 2108.

As we talk about passive solar heating and cooling, remember this is all part and parcel of your design thinking. Any change deer layout is an opportunity to get better flow through your house, better privacy or connection for your family and improve your home’s relationship with the sun. As with every design choice, you can get more than one benefit out of a single move adding a little trellis over your back patio can shade your west facing windows and help keep your house notably cooler in July and August.

But at the same time, it can also define and create the space of the patio and make it a more pleasant place to hang out any time of the day or year, and particularly in the case of a ranch With a walk out basement, which can have a really aggressive cliff wall effect along that two story portion in the back, a horizontal line created by a trellis can break up the cliff wall and make the house feel a little more grounded and smaller, reaching out to the side, to the side and connecting the house to nature.

That’s three stacked benefits for a very small and relatively inexpensive adjustment to your yard. You could make it even cheaper by making that shade out of some strung up triangular shade cloth, rather than even a wooden patio trellis. Stacked benefits like this are going to be common for passive cooling and passive stroller strategies. When you look for them, you’ll rarely take on a change that’s only for heating and cooling. In effect, you want to solve a cooling problem and also do it in a way that’s going to get you an esthetic win as well.

Today’s episode is all about those triple wins. I’m going to talk a little bit about some technological history. Get a little activist with you and then talk about how several of our founding mid-century designers, Eichler Cliff May and the earlier modernist Keck and Keck interfaced with passive cooling and passive solar ideas. And then we’ll do a breakdown of the different regions of the US and how you can best pair passive solar heating and cooling with mid-century design.

We’ll wrap up by some summary ideas of how you can apply passive solar cooling to your house, specifically as you think about a remodel. This is something I think about in every design that I take on for my clients, and it’s something that I encourage all of my ready to remodel students to think about extensively as they are going through the draft phase, once you’ve established what your house needs, what your family needs and the style of your goals, you can start to think about how to stack up Win, win situations that are not only going to improve the way you live in your house, but the way that it feels dim and moody and cozy or bright and light, and the way you use energy to lighten and to heat and cool your house.

One of the things I always do for myself and always guide my students through inside of ready to remodel is to diagram your house on a number of different levels. Not just thinking about the way you use a space, what a room is for, for watching TV, for hanging out, but think about the way that heat and light move through the house through the day.

Perhaps you’re hanging out in one room and not another, because it’s bright and comfortable at a certain time of day, or because it tends to overheat and become uncomfortable for similar or different reasons, starting to overlap the diagramming of how you want to use space, how spaces are adjacent to each other, the views you see out, the way that light and heat move through the house through the year and day, are all ways to start to make the most out of each individual design move.

Once you’ve done some basic diagramming exercises, which, by the way, you can certainly feel free to do just on the basis of this episode, you can also start to think about how you can layer multiple design solutions onto each other and get the best possible results out of planning your remodel. If you’re curious about this, you can learn more about how I stack up Win, win win design moves using the mid-century Master Plan method by heading over to check out my free master class, or also just to join us inside of ready to remodel and follow along the step by step guidance I take you through from asking yourself the right.

Questions about your home to getting the right answers. To personalize and tailor your house to fit your life specifically by checking out the course information at mid mod midwest.com/ready by tailoring the house to fit your life, I might very much be talking about tailoring your energy use to fit your ethical desires, taking advantage of some of the passive solar design principles I’m going to talk about today, and making some energy improvements to your house might be one way to make that house even more appropriately your home.

So I hope you enjoyed this episode. If you want to follow along, check out the show notes to see. I’m going to have some references I list. I’m going to point you to a couple of online resources and definitely have some sketches of the way I’ve used shading devices in and around mid-century homes and master plans that I’ve done for my clients. You’ll want to go to the show notes page at midmod-midwest.com/ 2108 see you there. So let’s begin with some history.

As always, the past is Prolog and the history of passive solar design has been around since forever. This is a place where I’m going to talk a little bit about vernacular architecture. And as I reflect on it, I don’t think I use the term vernacular very much in the mid mod remodel podcast context, which is silly, because I think about vernacular architecture all the time. It’s a huge part of my self-created design background and my interests.

Although the term itself is actually pretty snotty, it’s the kind of thing that’s used by people who consider themselves to be an expert when they refer to the good idea of people, they don’t consider to be expert as very surprising, and then they steal them. If you look it up, you’ll find a definition of vernacular architecture, something like a style designed based on local needs, availability of construction materials and reflecting local traditions, not using formally schooled architects for design, but relying on the skills and tradition of local builders.

This is, it’s, again, it’s a very snotty way to say common sense building, the way people have built, without having reference to design schools or official contractors, due to the planning and labor for them, and as mentioned in that definition, different from place to place, but really it just means common sense choices that respond to environmental conditions of the people, wherever they are.

So to respond to the conditions of your environment absolutely means you’re responding to the way the sun moves through your space, the way heat and cool cycles happen, and trying to use the power of the sun to warm up your house when you want it warmer and keep it cool when you want it cooler. If this has been around since the earliest human development, why isn’t it embedded in all of our design today? What happened if, literally, everybody used to know better, why don’t we design our houses with passive solar and passive cooling now?

Well, might you ask, this is just one more way in which industrialization, capitalism and Western society generally, has detached us from some of the practical solutions that have been common sense for people of the past. As people have gathered together into larger groupings, looked after by larger and larger civic organizations, we’ve often moved away from things like everyone getting to site their house in a place that makes sense for wind speed and direction and sun, and instead, we start drawing lines on maps and arranging streets in grids that, by the way, not part of today’s conversation.

But the original concept of an urban plan being a grid goes back to the Romans, who liked the idea that a military or police force could stand on a corner and see a long way in multiple directions and run straight to a problem if it came up eventually. As time went on, we just got out of the habit of planning for the experience of an individual building, and always planned a development out on a map, first dropping in a grid and directions seems useful, but sometimes they’re not even north, south, east, west, organizing our streets to be more accessible by car, or sometimes to be less accessible, as through streets by car, and then dropping the houses along a street one after another with a door facing east, west, north, or any direction whatsoever.

The other reason we lost sight of those highly efficient passive solar design principles that have been used in buildings since the dawn of time is that once we had more nonrenewable energy available, we started to just throw energy at the problem. And this probably really kicked into high gear with the ability to burn coal for heat. These days in America, we’re probably using natural gas or possibly even electricity.

But where is that electricity coming from? From power plants that might be nuclear or they might be coal or they might be hydropower, whatever that source is. We’re not thinking about sort of harvesting heat and cool from the local environment. We’re thinking about just throwing energy into the problem. I recently had a lovely chat with Adrian Kinney of Mid Mod Colorado, and that’s going to be on the podcast one of these weeks coming up soon. We will be talking about how this change from taking advantage of site principles and the passive solar and heat potential and cooling potential and went into using energy has really affected the Denver area, which, when it was originally built out in the mid-century era, used a lot of passive cooling strategies around houses.

But those have been abandoned for two reasons, and one is that the climate has changed, climate change, and yes, burning coal has contributed to that, meaning the winters are colder and the summers are hotter, and it’s just not possible to achieve human comfort with the old strategy of having good air venting so you could just flood the house with cool air at night and then button it up to keep relatively cool during the day.

But the other reason is that we have gotten used to throwing energy at the problem. In another way, we have now become more inured to the process of residential air conditioning. This really goes hand in hand with not just Denver, but how the West was settled in the late, mid-century era and beyond, places that were too hot to live in bulk during the summer, even back then, become accessible when we throw more power at the problem and run the air conditioning all summer long.

And this is why you see the population of a place like Phoenix boom from a little over 200,000 people in 1950 to 4.8 million. Today, the population of all of Arizona grew from less than 200,000 in 1900 to less than 750,000 in 1950 but then almost Dec doubled in a decade, and now it’s 10 times that much, over 7 million. The US population as a whole, by the way, has only doubled, a little more than doubled since 1950 so why is everyone just relocating to areas that are literal deserts, literally running out of water, as you keep reading articles about because it’s warm in the winter, which is pleasant, and in the summer, there’s air conditioning.

So we start to build houses that are even less considerate of their local environmental conditions when we have the ability to throw more power at the problem. And while insulation standards have improved a bit since the mid-century, era improved significantly. Really, we also just don’t plan our houses to be completely heatable or coolable by anything other than energy. Now, there have been moments in history since the mid-century when we have paid more attention to passive solar design and passive solar cooling, and those moments have a one to one correspondence with higher energy prices.

In the 1970s we had the oil crisis. Jimmy Carter put solar panels on the roof of the White House. My dad built a solar greenhouse on the back of his first home, a tricky old four square in the Camp Randall neighborhood of Madison, Wisconsin, and there’s a moment of enthusiastic young architects all over the country exploring Earth, sheltered design, passive solar and passive design houses built out of tires. There’s a there’s a big influx of people both, let’s say vernacular, people out of the design realm and people inside of design schools getting excited about alternatives to throwing energy at the problem.

But as oil prices came back down again, Crisis averted, suppressed, what have you, America gets just right back on her bullshit, and we get ever burgeoning house sizes going from the 70s straight on, through no attention paid to site design or passive solar or passive cooling at all, just running the HVAC system that’s heating, ventilating and air conditioning at all times of the day to create the human comfort that we want.

Now, there is a little bit of fun that we can have by reaching back before that time to mid-century history, there’s a bit of a crossover between mid-century era and passive solar design. And in this case, two things can be true. One, the mid-century era was not a time when we were thinking a lot about passive solar siting, that is putting a house in a place that responded specifically to the sun. We were building house after neighborhood after city totally based on grids, or later on, sort of cul de sac style neighborhoods, houses facing every direction.

And the siting of your house, the way that the House faces is one of the most baked in elements of your design. It’s the hardest thing to change. You are not going to lift up your ranch house built on a basement or set on a slab, rotate it until it has a better relationship with the sun, ignore the street, plop it back down again and go. You’re basically stuck with the way that your house is oriented from its original construction. So that is not the best. But at the same time, our mid-century forebears were practical minded people.

They did not like waste, and in building those houses, there were still a lot of craftsmen who cared about how they were doing their job. So an original, untouched mid-century house is at the very least, very airtight finishing drywall. Proto drywall with a half inch layer of plaster, and then sealing every corner there very thoroughly with, let’s say, possibly lead paint. Means that you’ve got a house that is snug, that holds its interior air, which means it might be better at temperature regulating than a newer house. Mine certainly is.

If you have ever had an energy audit done on your house, if you have a mid-century house that has not had any window replacements or window replacements done well, and that has not been significantly remodeled, added on to you’re going to find that it probably has a pretty good ability to retain its interior air and possibly to retain its interior temperature against swings outside. There’s a couple of other factors of mid-century houses that play to the advantage of passive solar and passive cooling.

Mid-century houses are often smaller and lower so they tend to hold their heat and cool through their compact design. They also have less big faces of wall two story or three story facades that the sun can beat down on and heat up really shine on a lot of bright summer heat, even in a modest mid-century house with relatively small or no roof overhangs, it’s pretty easy to keep the sun sign out on a hot day, and to our benefit today, even though most mid-century houses were dropped down into a blank, empty field in the 1950s and 60s when they were built.

Today, they’re often shaded with mature street trees, which is a huge boon in terms of local cooling effects. So we’re not starting from zero. We are so much better off than someone standing on the curb of their 90s McMansion trying to figure out how to make that more energy efficient. We also may benefit from the influence of certain designers from the mid-century era who were already interested in passive solar and passive cooling.

So the ideas of passive solar design had been picking up steam in Europe for a while in the early modern era, and here in the US, probably the designer most famously associated with passive solar is Keck and Keck, I should say this is a little bit more modern than mid-century modern. George and William Keck were brothers in born in Wisconsin and working largely in Illinois, who did modernist, international modernist homes that had a lot of glass walls, that used passive solar principles that had slat wall shade structures, overhangs meant to take advantage of passive solar principles.

There’s a great book about their history interests and some of their projects, Keck and Keck by Robert Boyce, which is published by Princeton Architectural Press. It’s either out of print or just wildly expensive, but you can actually read it in PDF form on the usmodernist.org website. I will put a link to it in the show notes so you can go and see some of their houses. They often they look pretty modest from the street. They often have kind of unassuming facades. They’re not very adventurous looking, but on the inside, they’re really reaching forward to what you would recognize as mid-century design, open plan areas, large expanses of glass wall.

In fact, they were the innovators of a thing that I noticed in the wild before I understood what it was, where there’s a large picture window of fixed glass, and then either below it or next to it, is what looks on the outside like a series of slats on the inside like a little door that flips open. And it’s a way to have a screened wall area that is operable separate from the glass. It separates your venting from your view, and it was sort of an early way to handle a screened wall system, and it can actually also be very effective, because you can have that screened wall happening in a shaded area where the roof overhangs totally protect the glass, so no light comes into the space, but a little bit of air from a sunny area can be circulated through.

Again, I will throw a couple of pictures of Keck and Keck houses into the show notes page, but they are absolutely starting to think about the exact kind of passive solar calculations that I learned at the desk of my first boss, where you’re looking at the angle of the sun in December and how far into a building it can penetrate the angle of the sun at the Spring and Fall equinoxes, and a sort of a mid-range, and then where the sun is going at the summer solstice. So you want to completely block out that high, hot summer sun and let the winter sun come in for passive solar heating and cooling.

This is, I think they’re probably doing this the most in the most formal and the most high end way of anything I’m aware of in the United States, like I said, Keck and Keck are modernists, not strictly Mid-century Modern designers. But if you’ve been kicking around the world of mid-century design at all, I can say the names Cliff May and Eichler to you, and you will feel like those are mid-century designers. They are, and they both pull. Lot of passive solar and passive cooling technology into their homes. Now Cliff may, in particular, I don’t know if they were reading about, if they were paying attention to the work that Keck and Keck were doing in the Midwest as they got started in California. Very likely they didn’t. But again, these are common sense ideas that have been around since forever.

So Cliff may certainly took his original designs for a California, a California Mid-century Modern ranch. The jumping off point was the design of vernacular ranch buildings that is common sense, built by regular people. Ranch buildings. They didn’t need to do a whole lot of passive solar heating in California, but they were great at blocking out the summer sun, so he protected his big glass windows of his open plan houses with deep roof overhangs, creating shady, cool veranda spaces running the length of the house.

And that’s a design he absolutely borrowed from the local design culture. Similarly, the designs that Joseph Eichler started turning out, and the people who copied him also picked up that feature, perhaps with a flat roof, but with a deep overhanging Eve to keep out unwanted added sunlight and other passive cooling features, like a backyard pool as an added source of evaporative cooling in a low humidity environment. I will very briefly touch on the tech of that later but just let’s note they’re already doing it.

This is a good idea. and it is not coming out of nowhere. It’s coming out of good design ideas of the past and paying attention to the local environment wherever you are. So when Cliff Mayes transferred his design ideas from California to Denver, he got interested in the idea of capturing prevailing winds, because there is a common direction of breeze in that area. It meant you could sight a house and put low windows on the breeze incoming side and high windows on the opposite, to encourage fresh air to blow right through, and to take any warm air that was inside the house and let it stack effect vent right through heat rises.

So as air movement is happening, you can kind of sweep in cool air and let it replace hot air, which goes out a high window at the back. Now, I’m not going to name check designs in other parts of the country, but as we look at the sort of geography of the US, we can see how different environmental conditions lead to different variations on the mid-century style, for example, in Florida, in the muggy climate, where there’s often higher humidity, you would not, for example, get any notable cooling effect from a pool next to the house.

You could feel cool when you jump into a pool, but having a pool next to a house at a humid environment isn’t going to help you create evaporative cooling. But we do see that they start to use a lot of concrete block and concrete floors throughout this area. The finished floor surface in a Florida House might be terrazzo, because any cool that could be captured during the evening could be stored up in a thermal mass of a heavier surface, rather than just lost in a simple stick framed structure.

Now a concrete block wall is never going to be a great insulator, but it is great thermal mass, meaning that if the house entirely cools off at night, and then you close it up, it’s going to hang onto that cool for a little bit longer. So the Florida house built with solid concrete floors, concrete walls, sometimes even a concrete roof, but very open to the inside, sometimes even open to the fresh air with Jazzy style windows that could be letting a breeze in through the course of the day or night. You’re flushing the house with cool when it’s available and then closing it up to seal in the cool when it’s not.

Here in the Midwest, where I’m based, we have and similarly, in the northeast, we have simply more complicated challenge, because we not only need to use passive cooling techniques, but we need to use passive solar heating techniques and possible in the winter. And this is the true magic of passive solar design. If we’re doing it right, we can lean into the calculation that ties to the natural movement of the Sun throughout the year, the movement of us around the sun to be clear, but due to the way that we are standing on our from our vantage point, it’s the way the sun is moving around us.

So from a person standing on the ground in the Midwest, it seems that the sun makes a higher path through the sky in the summer and a lower one in the winter, topping out at the summer solstice with the highest pass and the Winter Solstice with the lowest one. So you can calculate the angles of windows and roof overhang precisely and orient your house in a specific direction so that in winter, the sun will come into the house deeply, and you can plan for that sun to land on solid surfaces, like those concrete Florida houses.

You can have it hit a stone or brick or concrete wall or floor that will heat up during the day as the sun touches it, and then at night, slowly re radiate that heat back out. But the same windows and roof overhang can also, at the same time, completely block out the high summer sun, keeping the house shady and cooler in the summertime. So my background, my first job in architecture, was grounded in passive solar. I worked for a company called Whole trees, and we built timber frame homes that were straw bale insulated, sod roofed and always passive solar oriented.

One of the last projects of design that I worked on at that firm was my parents’ home, which they still live in, and it is a passive solar design. They have a large double height wall in the main living area of windows facing south, actually slightly southeast, and a very precisely calculated overhang, so that at the winter solstice, the sun comes all the way through the open dining room, warming up the concrete floor, all the way back through the door into the main floor bathroom, stopping just before it hits the cabinet of the vanity. And at the height of summer, the shade line is outside the house.

That house does not have a furnace. It doesn’t use forced air to heat it. It does have solar panels in the backyard that have the ability to collect heat and run it through pipes in the floor, but also the floor itself can be naturally warmed by the sunshine, so their best way to heat the house up is just the sun shining on the panels out behind the house and on the floor itself.

They also have a backup natural gas heat source for the floors, and they have a wood stove that they also use, but they often try to see how long I can push it before they have to kick in the gas or light a fire. And every year, it’s a reporting I get regularly when they say, Nope, haven’t needed a fire yet. Haven’t turned on the gas yet. Counter intuitively, some of the coldest days in Wisconsin are some of the days when they do not use any active heat source. That’s because here in Wisconsin, it’s a common weather pattern that the coldest days are also very clear, whereas mild days often pair with cloudy weather. So when it’s been cloudy for too many days in a row, they do have to hit light a fire or fire up their gas powered heat.

But as long as the sun is shining brightly, we might be in a polar vortex of subzero temperatures for days, and everyone inside their house is walking around in a T shirt using no other heat than the sun. I also designed their house without an air conditioning system, and they have lived in it mostly comfortably for the last six years, because it stays cool through most of the days, as long as it’s cool at night and it manages to hold its cool remarkably well. It’s just a very comfortable house, occasionally when it’s hot for a long time, or particularly when it’s muggy, and it’s not a good idea to let a lot of humidity in the house. By opening the windows at night, the heat starts to add up in the house, it starts to be a little less comfortable.

So just this spring, they have installed a mini split system, not necessarily even for cooling, but because the humidity does add up, and this is going to have a benefit to quietly and efficiently dehumidify the house as well as cooling it slightly, I think they could have probably continued living like this forever. They largely worry about cooling when they have guests over, and they’re scheduled to host a series of extended family and friends this summer, and that’s what ended up cracking them to add AC to the house in a mini split system.

So their house is not a mid-century house, but I bring it up just to let you know that I know whereof I speak. So when you are thinking about your home, having dug through all this historical context and done this roundup of early mid-century houses that had some passive solar cooling, because I’m into them. Let’s figure out what you can do for your home today in a remodel. Step one is assess the solar potential right now. So let’s talk about the commonsense background of passive solar heating and cooling.

To do this, imagine yourself at an outdoor event on a hot summer day, a music festival, a family picnic, where do you stand? Do you choose to have a conversation with someone standing in the middle of the grass or on a black top surface? Now, I know there are people out there who like sun much more than I do, but remember, this is super freaking hot in this example, maybe dangerously hot. So are you going to stand, for example, again, in the sun or under the shade of a tent or a tree? Do you want to stand in the middle of a densely packed crowd, hemmed in by other people, or a little apart where you can capture some fresh air? Do you want to stand in the middle of a field or next to a lake on the hottest days?

I’m guessing that even heat lovers would answer in the grass, in the shade, where I can feel a breeze, and sure, next to a lake sounds great. You might not know the why behind those preferences, or maybe you do, but it’s pretty easy to explain. So let me give you a quick round up. You want to stand in the shade because of solar radiation? When sunshine hits a surface, it warms it up. If you are that surface, you will feel warmer when the sun touches you than when it does not. On the hottest of days, standing in the shade or in direct sun can make a huge difference to your thermal comfort.

For solar radiation, the type of surface also makes a difference. Some surfaces Della. Black sunlight, they bounce it right back off like a light colored tent canopy. But others absorb that heat and store it, sometimes radiating it back a black top parking lot, for example, will gather heat until it is painfully hot to touch, and then it will also radiate that heat back out into its environment, making you feel warm, even if you only stand right next to it without touching it. The grass or tree you could stand underneath is also absorbing that sun energy. But instead of storing it and radiating it like the black top, it’s converting it into energy through photosynthesis to grow more plant.

This is an absolute Win win scenario in terms of passive solar. It’s keeping the heat off of you. It’s also making more shade for the future out of solar energy. This is why you’d rather stand in shady grass than on sunny blacktop to step away from our Summer Picnic example, that effect of heat baking into absorbent, dark surfaces and then radiating back can be really magnified the more of those surfaces are concentrated together.

This in an urban context, is known as a heat island effect, when the aggregate of all of the square footage of a city made up of paved road and dark rooftops, each of those surfaces contributes to the heat, and the result is summer temperatures that are two to five degrees warmer in the day and sometimes 20 degrees warmer at night, when you could be cooling off your living spaces with open windows, hypothetically, than adjacent, nearby spaces that don’t have the same concentration of dark absorbent surfaces.

Remember I said we are very lucky in most mid-century neighborhoods to have the benefit of well grown neighborhood and street trees anytime your concrete or asphalt or blacktop Street is shaded by trees, anytime the sun is not touching it, we’re doing better on that heat island effect than if we’re in a space where all of the streets are exposed to the sun all of the Time, having fewer paved areas using permeable or more reflective surfaces for our paved areas, planting and supporting more trees to shade the paved areas and rooftops, and using lighter colored reflective materials on rooftops and pavement, and adding in green rooftop systems are all methods that city environments try to use to mitigate a heat island effect.

As an individual homeowner, you can’t affect all of the surrounding area around you, but you can make your tiny island as green, as shaded as unblack, topped as UN hard absorbent, surfaced as possible for the best results. Okay, let’s come back to our Summer Picnic analogy. Now we know why we want to stand in the shade of a tree on lawn instead of in the middle of a blacktop surface with no tent. We also might want to stand away from other people, and if ideally possible, near a lake, because both of those things are going to allow a wind to move past us and hopefully for moisture to be evaporated. And this gets us to the principle of evaporative cooling.

This is going to be most effective in low humidity, high heat areas, California, Arizona, come to mind. Basically, evaporative cooling is when water is transformed into a vapor. It absorbs heat from the surrounding environment. In that process, this lowers the air temperature and can be used to feel cooler. This is what’s happening when you’re sweaty and you feel a breeze. This is why we sweat. Actually, we put moisture, we give up moisture from our bodies, put it onto our surfaces so that the potential for evaporative cooling, can cool us down, then, in theory, we just drink more water to get that moisture back again.

One more principle. I’m not sure how to make a picnic analogy out of this, but you want to think about stack effect cooling, the fact that heat rises can sometimes be used to create a breeze or air movement, which again, allows us to encourage evaporative cooling, and just to give us a sense of relief from still air, so you can create stack effect cooling by having an ability for warm air to be vented at the top of a contained area as cool area is then drawn in To refill that space from a shadier space. So particularly in your own home, you can potentially do this with no remodel whatsoever.

You just think about morning or evening, which side of the house is getting sun right now, and which side of this house is not getting sun right now. On the side of the house that’s not getting sun, you want to open low windows to allow cool air to move in. Then if you have a little bit of your window is getting sun heat right now, you probably want to draw curtains or pull blinds, but you might open it just a crack at the top to let hot air go out of the house on that side, and then cool air to be drawn in from the shady side to refill the house. With more pleasant air.

All of these principles, though standing in the shade, standing on grass, not being surrounded by asphalt, and allowing for evaporative cooling to take place, can be translated to your house. You want to keep your surfaces light and if possible, use literal greenery, plants to block to be between you and the sun in hot times, you want to let breezes flow through the house. This is definitely going to come up in the idea of an insulated attic, or a raised surface to allow hot air to go out. And you want to keep the sun off the house in as many ways as possible, shade from plants, shade from structure, shade from shades. You want to pay attention to the direction your sun is coming from. Let’s, let’s think about big picture for a moment.

Every floor plan change, every time you’re going to think about a small addition or a change to your layout, this is your opportunity to get multiple benefits from one small change. So you can think about this as an opportunity to improve tight corners, inadequate kitchen space, not enough privacy for your bedrooms. But you can also tune those specific layout improvements to also improve your relationship with the sun. Designing for Daylight is one area in which building new is always going to be a little bit easier to accomplish than a remodeling project. Like I said, we are stuck with the site choices, the directionality that our mid-century home builders chose for us.

When you start from scratch, you can choose your orientation to the sun and the wind. With an existing home, you get what the original builder gave you, but we can still make improvements. We just have to be creative to get those results. So begin by assessing your solar gain situation. What are the hot and cool times of the day and year? Where does the sun hit your house at those times? When does direct sunshine shine into or build out hit the outer walls of your house? So you can make improvements by allowing the sunlight to enter the house strategically and directing it to heat, absorb its surfaces, to create thermal mass, when you want to passive solar heat the house.

On the other hand, right now we’re in the summer. I’m talking to you. It’s currently May. It’ll be May when this episode drops, and you’re probably thinking about passive solar cooling technologies and techniques. So in this case, what you’re going to want to do is block the sunlight from entering the house and take advantage of stack effect air circulation. That means opening windows on the low side where it’s cool and the high side where it’s warm. In both cases, you will need adequate insulation on the whole house to extend the heating or cooling that you collect under the favorable conditions throughout a 24 hour period.

As you’re thinking about changes, as a rule of thumb, you’re looking to add more glass surface to your south side of the wall, maybe even to your east, and minimize the large windows that face west, because they will almost always be letting more heat in than you want. In the hottest part of the days and in the swing season, as you get into high summer and late fall, it can be particularly hard to deal with west facing windows.

Now you might have just mentally run through what I’ve asked you to do, assess your solar situation and say, Della I have a wall of glass that faces West. Well, heck, so in that situation, yes, your original designer has not made your life easy, but this is where you’re going to think about what you can do to create shade and block the sun from coming into your west facing windows.

This might be plantings, particularly if you want that Western sun in the winter. You might think about the kind of plantings that drop their leaves. This might be a slow growing problem. Oak trees are perfect for this. They’re going to grow very slowly, though, but you can think about something faster growing that’s going to give you pretty good greenery, shade, blockage in the summer, and then be mostly bare branches in the winter and let the sun shine in you can try to solve the problem of specifically too many west facing windows with extended roof overhangs, but the sun coming in your windows at its sunset hour is going to be really hard to black block with even the deepest of overhangs.

So you might need to think about actually a vertical shade element, curtains, perhaps, but also maybe a shade cloth that you string across a wall of the back of your patio between several elements, so that you can literally block out that horizontal, angled sun that’s getting into your house.

Any other surface that it touches before it gets into your house is going to be less adding heat to the house than once it’s come through the glass and touched a surface inside your house. Let’s think about general principles and best practices for designing with daylight, passive solar design is all about making the most of the daylight, letting it work where it wants, where you want it to, and not to come into the house and affect your life where you don’t. So you’re going to think about the orientation this I know, as I’ve just said can’t change.

But if you’re thinking about an addition, you’re pushing out a living room or an owner’s bedroom into the backyard, you might be able to put it on in such a way that you can gather more sunlight to add more passive solar heating, or that you can create a shady patch that maybe even blocks other windows. You can put less Windows towards the south or west if you’re trying to keep things cool, or Windows with a good overhang to the south and no windows to the west, more East facing windows.

Thinking about where is the best solar potential in your house may influence where you put a small addition, particularly where you put something like a screen porch or a sunroom that can help direct light into or away from the rest of the house. Calculating how to let light in to affect your heating and cooling load, and then how to insulate to take advantage of it is an integral part of designing a good addition.

For buildings in hot climates. It’s probably most important to focus on indirect light sources, letting light come into the house only through the north and east side, while keeping any heat gain out of the building.

In a cooler or a climate that’s warm and cool, like the Midwest, direct light can be harnessed as a home heat source through passive solar. So buildings with a south facing aspect can let the winter sunshine in onto ideally a thick thermal surface, concrete, brick, stone, something that can absorb the heat in the daytime and then release it slowly after the light has gone. Like a concrete floor or a stone fireplace.

A well-insulated building capable of holding edge that heat with good ventilation to let out extra heat, when necessary, can then offset some, or even all of its heating needs with sun on sunny days.

Passive solar, like I said about my parents’ house is too unpredictable to be your only heat source. It can’t replace your furnace entirely, but it can seriously offset your artificial heat sources. The kind of things we’ve been using throw a little energy at the problem since the early days of the Industrial Revolution.

You do want to pay attention to when you’re thinking about your house, where is the light coming from? And where would you like the light to be coming from? North Light is best used for art, for bringing in indirect light. It has no harsh glare. And it doesn’t create shadows. It just brings in daylight to the house. When it’s a bright day outside, it brings a little more brightness.

So a north facing window or a North oriented skylight can be really beautiful, even light. East facing windows gather at morning light, sunrises, even moonrises, and they can be great for warming up a house even after a cool night, but they never threaten you with overheating in the summer.

South facing windows can run the risk of overheating and glare. They can also create harsh shadows and fade out your furniture, but it’s relatively easy to control them with well calculated shade devices like roof overhangs, awnings or trellises.

West light is the most unruly. It can be beautiful, low slanting sunset light, particularly in the late summer, but it can also add unpleasant glare and a lot of heat. So this is the most important light to control with shade from trees, adjacent structures, or even at last resort, curtains.

This what I mentioned before, controlling light with trees is my best recommendation. Planting trees right away, or taking advantage of existing trees is one of the best passive solar techniques, because deciduous trees can block out the summer sun heat and let in the Winter Light heat into when you want it and when you don’t want it, or when you don’t want it and when you want it, when all else fails, though, you can turn to window treatments.

You can just use shades inside your glass, even if you can’t keep the sun from hitting the outside the glass. But I would also say, consider roof overhangs consider I mean, if you’re going with a vintage twee house, you’ll see on a lot of homes which are lined up along a street facing west, the front and side windows will have those big, deep metal awnings that reach out.

They look like just a cutesy old fashioned thing, but what they’re doing is they’re preventing a whole lot of heat gain from west facing light, sometimes south, but mostly you’ll see those on west facing windows.

You can also take advantage of stack ventilation by making a pathway for hot air to escape at the top of your house. This might be something you want to do manually, or it might be you install a couple of Velux brand skylights that are meant to open when your house hits a certain temperature. Just let hot air rise and go right out, which will then draw in cool air from lower windows and create a breeze, even in still climates, outside.

Anytime you’re not dealing with humidity, creating natural breezes within your house is a brilliant idea and a best way to cool.

There are a number of ways to keep air moving throughout your house without running your air conditioning unit. For one thing, you might have a setting on your HVAC system that just vents the house, that just has a fan running that circulates the air inside of the house. If you live in a Midwestern environment and you have a basement under your house, you might find that the basement is always a little cooler than the upstairs. That’s because it’s gotten it’s in contact with the natural cool of the ground. The temperature of the soil in most places, if you get down low enough, is about 55 degrees. So the temperature at the bottom of your basement is also about 55 degrees.

And you can borrow that heat and circulate it through the house without running your air conditioning unit, while just running the whole house fan. You can also use a whole house fan, marketed and installed separately from your HVAC system. You can also use ceiling fans, the larger and slower the better, to gently circulate the air in the house. This, by the way, the stack effect cooling is also a key feature of removing heat from the environment of your house with a vented attic.

Now, if you live in a flat roof house, I’ll talk to you in a moment, but if you live in a branch house with a triangular Gable attic, it should be designed to help you keep the house cooler in the summer, even if it has a dark asphalt tile, an asphalt shingle roof, what should be happening is that air should be drawn up from the vents at the soffits and then be released either at the ends through two end cable vents and or up along the ridge through a ridge vent.

And it should just naturally be circulating as heat in the attic builds up. It should be going up and out through the top vent and being drawn back in through the lower vents, that effect can actually create a movement of cool air that flows up from the ground along the outside walls of your house and into those solid vents, creating a cooler environment around your whole house, not just getting the heat out of your attic so it’s not slowly working its way down through the ceiling.

This is hugely important to make sure that your attic is venting properly, and it’s a good maintenance task, particularly if you live in kind of a time capsule house, to make sure that a, the under soffit vents for your attic are adequately sized, they often are not, and B, that they haven’t filled up with dust and schmutz and detritus. Over the years, when I move into my house, the soffit vents were a series of little, two inch diameter round plugs with little vents in them. They were completely filled with schmutz, and also, they were not sized correctly.

This is a place where you might want to just hit the internet and get a calculation for the appropriate area of roof vents. I went ahead and cut those all out, actually, let’s be clear, my father went ahead and cut those all out and replaced them with soffit vents properly sized for my bridge vents, because it was the most important thing to him about having his daughter buy a house. Bless his heart. Thanks, dad. I appreciate it. But thinking about ways that you can create, ways to let heat rise up and out of your house to get it out of the house, and also to create a breeze where there is one for no energy cost. Are two brilliant ways to use passive cooling techniques to keep your house cool.

Before we wrap up, I’m going to use one more keyword that you might want to lean into and or do a little more research on, which is the thermal flywheel effect I’d mentioned letting the sun hit a solid surface, like a concrete wall or floor, a brick or a stone fireplace. This thermal mass will slowly heat up being touched by the sun and then slowly re-release that heat over time. This is known as a flywheel effect, because it’s slowly it’s sort of slowing the natural fast process. It’s dragging on the system of thermal change throughout the course of the day and night.

So anything you can do to slow down the process, so you can borrow coolness in the night and let that coolness last as long as possible into the day, even if it just means you don’t need to run your AC until later in the day. Is a brilliant thing from a purely passive solar perspective, from a cultural, large scale energy use perspective, you might also be better served by running your AC for a brief amount of time in the morning and then closing down the house to know that it’s going to stay cool throughout the day, rather than letting yourself get to that last hottest moment of the day And then running your AC when everyone else is also running theirs and creating the largest load on your local power system.

All of our local power stations are sized for our maximum load, so anytime we can offset and use power when it’s less being used by other people, is good for our general power requirements and the number of new coal fired power plants that are being constructed across the US. Oh, okay, one more little band box to stand on that’s not strictly related to passive solar heating and cooling, which is to think about what means you’re using to heat and cool your house, and whenever possible, I recommend to my clients and students that you think about maybe converting from a fixed energy source, like if you heat and cool with gas, you can only heat and cool and gas if you heat and cool or maybe even cook on your stove with electricity.

We have the power in the future to vote or to influence our power companies to choose more sustainable sources of gathering that power. So. So it might allow us to do your heating and cooling with solar or with wind or with hydro in the future, if you’ve already got a system set up to use electric power to heat and cool your house, in addition to the passive solar heating and cooling techniques that we’ve just been talking about.

I’m going to put some sketches of particularly outdoor rooms into the show notes for this page, because that is going to be one of your best ways to control the thermal environment inside your house, unless you’re going to go ahead and do a big addition, as I say, pushing out a sunroom, a den, an owner suite into the backyard or a new entry into the front, you’re probably most easily going to be able to change The way the sun doesn’t get into your house by a shade cloth, a trellis plantings, something happening in an outdoor room.

So I’m going to have some examples of pretty shade structures that not only shade the house and keep sun out in the winter, but in the summer, but also create pleasant spaces to be in outside that define a private zone, a place to be at rest, and that can even improve the esthetic potential of your house. That is a three for one win. That is exactly the kind of thing we’re looking for when we plan and remodel for a mid-century house. To see a few of those sketched examples, pop over to the show notes page at mid mod midwest.com/ 2108

All right, let’s celebrate mid-century design. Our mid-century house feature of the week is going to be the Keck and Keck designed louver window separated from a picture window, and I will link to an Instagram story I put together a highlight that I’ve saved over, actually, several stories when I first started seeing this window design in the wild, I had noticed it on a couple of houses, and then I had a client’s house that had this design.

In each bedroom there was a fixed glass relatively tall vertical window, and then underneath it a little panel with a little wooden hatch that could flip down and open into the room, and beyond it was a bit of screen and louver vents going right to the outside of the house. Such an interesting way to do a screened window that didn’t have screen covering the glass. All year round, you could get all the fresh air you wanted. It was in a relatively controlled environment, and then you had this beautiful, inexpensive piece of fixed, insulated glass above it, and since that time, I’ve encountered this in homes in my own neighborhood, in houses I’ve read about, and in several other clients’ homes with several variations of the louver window design.

I think this is such a brilliant idea, and honestly, it’s the sort of thing that I wish I could design into every house I do a master plan for, except that I think that there’s no way to purchase and have installed one of these louver window vent areas. I think they were all custom built on site by the local contractors for those individual houses, by the way, if I’m wrong, if anyone is listening to this now, and you know of a company that makes little hatch vent louver areas that you can put next to a fixed glass window, and you can purchase that and have it installed.

That’s the sort of thing that a modern contractor is asking for. They do not want to site create all of the windows from scratch, but I would love to be able to specify this for my clients who don’t have it, because it is such a brilliant design. I would love to have it in my own home. I’ll put some pictures of how that’s cool onto the show notes page.

If you’ve heard of this, if you’ve been in a house that had designs like this, if you grew up in one, I’d love to hear your opinions about it. Reach out to me on Instagram. Send me some pictures. Send me your memories of what it was like, convenient, wonderful, awful got in the way of the furniture, made it hard to walk along the walls. Whatever your thoughts are, I would love to hear them.

So pop on over to mid mod Midwest on Instagram and tell me what you think. And go on over to the show notes page to see some examples of a louver vent window and fixed glass system that, as far as I can tell, was innovated by Keck and Keck as architects here in the United States, hopefully you’ve gotten some practical tips on how to think about adding a little passive solar, heating and cooling win to your house, no matter what you’re planning to do to it. Large plans, small plans, just getting a tree and planting it in the sunniest spot in your yard this summer, maybe to block light hitting a western wall.

And then next week, I will be back with some housing history and philosophy getting into the contrasting development of mid-century and British public and private housing projects in the mid-century era. So stick around for some more nerdery next week. And in the meantime, I don’t know, maybe go plant a tree and add a little passive cooling to your yard.

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