Urban Hot Spot? Here's a creative solution!

Tree

When Kassel University and Dr. Sanda Lenzholzer mapped the urban climate of Arnhem, Netherlands, they identified several 'hot spots'. The red splotches on the map indicate places where people would be overheated on summer days.

Hot spot in ArnhemArnhem Municipality, Netherlands

Sanda was not satisfied with simply identifying hot spots - she wanted to do something to make them cooler. An analysis of the microclimate of these locations identified some typical urban heat island (UHI) problems: too many hard surfaces and too few trees. The red area outlined with a pink ring is a densely populated area centred on the Graaf Ottoplein square that is almost devoid of trees. Sanda wondered how she could get more trees growing in that neighbourhood. She also wondered if there was some way to do it while educating the public as to the microclimatic value of trees in urban areas so that they might also take action around their own houses.

It is well known to landscape architects that trees have many microclimate-modifying characteristics. They intercept solar radiation before it reaches the ground which means cooler surface temperatures in the shade of trees and consequently less terrestrial radiation emitted by these surfaces. Evapotranspiration from their leaves humidifies and cools the air. The cumulative effect of many trees means that urban areas with a larger amount of tree cover are cooler and more thermally comfortable than areas with few trees and a large amount of hard surfaces. Furthermore trees can filter fine dust from the air and remove carbon dioxide from the air. Trees have many benefits for urban climate!

Sanda describes their thinking. "We wanted to raise more awareness of people for these benefits of trees on urban climate. We think that is important that people know the role that trees play in providing more pleasant microclimatic environments in cities. And because nobody in the Netherlands or elsewhere has raised awareness for the important role that trees play in urban climate before in a very explicit way, we wanted to be the first to do so."

So she collaborated with some creative friends and designers, and they came up with a unique idea.

Graaf ottoplein even larger imageGoogle Earth image of Graaf Ottoplein, Arnhem, Netherlands

"We inaugurated the world’s first ‘urban climate tree’. The ‘urban climate tree’ is a young Sophora japonica tree that was planted on Graaf Ottoplein square. This square lies in the middle of the neighbourhood that has heat problems and thus was an ideal location to demonstrate the positive effects of a tree. Apart from that, the square itself also has too many stony surfaces that add to the heat problems, and thus needs more trees. The ‘urban climate tree’ itself is surrounded by a ring shaped piece of art made from Cor Ten steel that explains the role of a tree on urban climate. Translated from Dutch it says: ‘tree=coolness= fresh air= wind protection=urban climate=’ The text on the ring can thus be read in a loop emphasizing that all these benefits are always connected with each other."

And they made it into a celebration. Dr. Lenzholzer continues "The inauguration ceremony was opened by the inventor of the ‘urban climate tree’ idea, Frans Tak, followed by a brief introduction that I gave on the role of trees on urban climate. Then the alderman Henk Kok unveiled the ring around the tree and highlighted the role of trees for urban climate in the neighbourhood where it is placed. And last but not least, he emphasized how proud he is of having the world’s first urban climate tree in the city of Arnhem."

UnveilingUnveiling the ring.  Photo Credit: Han Koppers

"After the inauguration ceremony we held a mini-symposium in the neighbourhood centre where local speakers gave presentations about the importance of trees and greenery on urban climate. They showed what can be done in such a densely built- up area as the neighbourhood that is now home to the world’s first urban climate tree. "

TreeDr. Sanda Lenzholzer (left) and the urban climate tree.  Photo credit: Han Koppers

It's very fitting that one of the common names for the Sophora japonica is Scholar tree. Clearly scholars are doing something very good for the urban microclimate of Arnhem and hopefully the initiative will spread into an urban climate forest around the world.

 

 

 

 

Inspirational!

 

 

 

 

 

 

 

 

Enjoying the fruits of my designs

  Cathy and Karen canoe drawingI’m taking a break from work and from blogging… in fact I’m taking a break from the digital universe. For the next few weeks I’m going to be at a rustic cottage in northern Saskatchewan where I’ll be enjoying the fruits of my microclimatic labour and I really, truly will be off-line! The cottage has no wifi, no cable tv, no cellphone coverage, and until a few years ago no land-line telephone.

The environment around our cottage has been designed so that every moment of the day there are microclimatically-appropriate places to accommodate our every whim. When we wake up in the morning we take our coffee down to the blazing sunshine on the dock. Cool Saskatchewan mornings are tempered by the solar radiation reflected off the pristine spring-fed lake. After breakfast we golf at a fun little course that has just the right amount of sun and shade for a morning game. Lunch is on the back deck in magnificent sunshine that beams onto the area from 11:30-1:30 and then agreeably passes behind some beautiful Betula papyrifera that we strategically planted twenty years ago. The early afternoon often brings a snooze on the now-shaded deck, before a swim in the sun-warmed waters. Dinner (‘supper’ in Saskatchewan) is held on the back deck where coals from a birchwood fire gently brown shishliki provided by neighbour Tom. Delicious! And after supper I paddle the canoe out onto the lake and pick up a few pickerel for tomorrow’s breakfast while I watch the northern sun angle slowly across the landscape, lingering while the sky turns crimson, fuschia, then peach, before finally gives way to magnificent aurora borealis. Our microclimatic day is complete and we sleep in a quiet so profound that I sometimes wake with my ears almost hurting from the lack of sound waves.

When I get back from this incredible gift of a break I have some big plans for posts to my blog. It’ll probably be hot, humid and hazy in early August so Dr. Drew Graham and I will be writing about his study that investigated the relationship between the amount of canopy cover in a neighbourhood in Toronto and the number of emergency response calls during heat waves. Could the number of trees in a neighbourhood actually affect the chances of people needing medical aid during hot weather? Stay tuned.

I’m also planning a collaborative post with Graham Slater who did a remarkable study of the temperature and humidity profile in neighbourhood parks in Toronto. This ground-breaking work won the top ASLA Student Research Award. They don’t often give out an Award of Excellence, but they did for Graham’s work. I think you’ll be fascinated to hear the results.

And I’m hoping that Dr. Sanda Lenzholzer of Wageningen University in the Netherlands will provide a post on urban climate myth-busting. You won’t want to miss that!

So I’m signing off for a few weeks. If you have any questions or issues that you’d like me to write about, please send me an email at rbrown@uoguelph.ca.

But I won’t see them until August. In the meantime I’ll be enjoying the benefits of years of designing with microclimate.

Enjoying the fruits of my designs

  Cathy and Karen canoe drawingI’m taking a break from work and from blogging… in fact I’m taking a break from the digital universe. For the next few weeks I’m going to be at a rustic cottage in northern Saskatchewan where I’ll be enjoying the fruits of my microclimatic labour and I really, truly will be off-line! The cottage has no wifi, no cable tv, no cellphone coverage, and until a few years ago no land-line telephone.

The environment around our cottage has been designed so that every moment of the day there are microclimatically-appropriate places to accommodate our every whim. When we wake up in the morning we take our coffee down to the blazing sunshine on the dock. Cool Saskatchewan mornings are tempered by the solar radiation reflected off the pristine spring-fed lake. After breakfast we golf at a fun little course that has just the right amount of sun and shade for a morning game. Lunch is on the back deck in magnificent sunshine that beams onto the area from 11:30-1:30 and then agreeably passes behind some beautiful Betula papyrifera that we strategically planted twenty years ago. The early afternoon often brings a snooze on the now-shaded deck, before a swim in the sun-warmed waters. Dinner (‘supper’ in Saskatchewan) is held on the back deck where coals from a birchwood fire gently brown shishliki provided by neighbour Tom. Delicious! And after supper I paddle the canoe out onto the lake and pick up a few pickerel for tomorrow’s breakfast while I watch the northern sun angle slowly across the landscape, lingering while the sky turns crimson, fuschia, then peach, before finally gives way to magnificent aurora borealis. Our microclimatic day is complete and we sleep in a quiet so profound that I sometimes wake with my ears almost hurting from the lack of sound waves.

When I get back from this incredible gift of a break I have some big plans for posts to my blog. It’ll probably be hot, humid and hazy in early August so Dr. Drew Graham and I will be writing about his study that investigated the relationship between the amount of canopy cover in a neighbourhood in Toronto and the number of emergency response calls during heat waves. Could the number of trees in a neighbourhood actually affect the chances of people needing medical aid during hot weather? Stay tuned.

I’m also planning a collaborative post with Graham Slater who did a remarkable study of the temperature and humidity profile in neighbourhood parks in Toronto. This ground-breaking work won the top ASLA Student Research Award. They don’t often give out an Award of Excellence, but they did for Graham’s work. I think you’ll be fascinated to hear the results.

And I’m hoping that Dr. Sanda Lenzholzer of Wageningen University in the Netherlands will provide a post on urban climate myth-busting. You won’t want to miss that!

So I’m signing off for a few weeks. If you have any questions or issues that you’d like me to write about, please send me an email at rbrown@uoguelph.ca.

But I won’t see them until August. In the meantime I’ll be enjoying the benefits of years of designing with microclimate.

Not all Shade Trees are Created Equal

  2 things to consider when selecting the most appropriate species

FLIR2100

When it comes to producing shade not all trees are created equal. But no single species is the best to use in all situations. You need to match the most appropriate species with the intended use of a place. A school playground, for example, is intensively used during spring and fall but is often underused during summer months. Trees that provide shade early in the spring and hold their leaves late into the fall will provide shade when school is in session and the kind of shade that they provide in the middle of summer is far less important. In contrast, many urban parks with playgrounds are used more in the summer when kids are on break from school. Trees that provide a heavy shade in mid-summer might be preferred in these locations, and whether or not they leaf early or late is not as important.

There are two main characteristics of trees that will have the greatest impact on your decision on how to provide the best shade for any given situation:

  • leafing period; and
  • density of the canopy.

There’s a table of this information that you can refer to in “Microclimatic Landscape Design”, a book that Terry Gillespie and I published with John Wiley & Sons, New York. Many trees are not particularly distinctive in either leafing period or density of shade, but a few are noteworthy.

Trees that tend to leaf later in the spring and drop their leaves earlier in the fall include:

  • Catalpa speciosa
  • Juglans nigra
  • Tilia cordata

Trees that leaf earlier in the spring and hold them later into the fall include:

  • Acer platanoides
  • Aesculus hippocastanum

Trees that produce particularly heavy shade in summer include:

  • Acer platanoides
  • Fagus sylvatica
  • Juglans nigra
  • Tilia cordata. 

Trees that have a particularly light shade in summer include:

  • Gleditsia triacanthos inermis
  • Carya ovata.

The list of trees in the book is far from complete. More studies need to be done to fill in the empty spaces in the existing list and test other trees. And of course there can be a lot of variation among individual trees of the same species depending on health and size. But by the very nature of evidence-based landscape architecture we have to use the best information available, even if it’s incomplete.

You'll notice that there are several non-native species on these lists.  I encourage people to use native or non-invasive species whenever possible, especially when planting in or near a natural area. Acer platanoides is known to be an invasive species in southern Ontario but has one of the densest canopies and provides heavy shade. I would encourage its use only in situations such as highly-urbanized locations where it can provide important cooling of the urban heat island.

Maple blue Birch greenI walked around my neighbourhood and took thermal images of the shade created by different species of trees growing side by side. In the image above the coolest temperatures (dark blue) were in the shade of an Acer platanoides while right beside it the temperature of the asphalt in the shade of a Betula papyrifera (yellow/green) was warmer. The warmest surface temperatures (red, orange and white) were of asphalt in the full sun.

Maple blue Honeylocust yellow

This image shows again the coolest surface temperatures (dark blue) in the shade of an Acer platanoides, warmer surfaces (green and yellow) in the shade of a Gleditisa triacanthos inermis in the foreground, and the warmest surface temperatures (red and white) were unshaded from the sun.

If you were designing an outdoor café that the owner wants to open early in the spring and stay open late into the fall you might want to select trees that leaf late and drop their leaves early so that the solar radiation can warm customers on cool days. Alternatively in designing a caféwhere the owner wants to focus on the summertime lunch crowd you might select trees that provide a heavy shade when in full leaf.

There are many things that need to be considered when selecting which tree to plant but make sure that you think about the leafing period and the density of the canopy, and how these characteristics will affect the long term use of the place.

 

References

Brown, Robert D. and Terry J. Gillespie. 1995. Microclimatic Landscape Design: Creating Thermal Comfort and Energy Efficiency. John Wiley & Sons, New York.

Brown, Robert D. 2010. Design with Microclimate: The Secret to Comfortable Outdoor Space. Island Press, Washington D.C.

 

 

 

 

Trees causing air pollution?! Say it ain’t so, Joe!

4 Species to Avoid and 3 Species to Plant It’s well known that trees remove pollutants while purifying and humidifying the air. While this is true in many cases, it turns out that there's another side to the story. And, like so many stories, this one came from Hollywood.

Starting in the early 1940s a foul smelling, throat-burning, plant-killing fog would roll into Los Angeles without warning and for no apparent reason. Residents were understandably upset. It ruined the magnificent Los Angeles weather. It took many years to solve the puzzle of why this apparent mixture of smoke and fog, which became known as smog, formed in this area. And when the mechanism was finally revealed it involved… believe it or not… trees!

Trees produce isoprene which seems to protect the leaves against damage at high temperatures. As the air temperature goes up, trees produce more isoprene and much of it escapes through the stomata on leaves and wafts into the atmosphere. During beautiful hot, sunny southern California weather large amounts of isoprene were being injected into the air by trees. Isoprene is totally natural and there is no environmental threat when trees emit it in natural settings. However, when isoprene is chemically altered through exposure to solar radiation it can then react with nitrogen oxides in vehicle exhaust to create smog. And in the 1940s with cars becoming more common, the Los Angeles basin with its low winds had all the essential ingredients for smog formation.

In suburban and rural areas the amount of nitrogen oxide is typically very small and the potential for smog production is also very small. So the species of trees growing in these locations do not need to be low isoprene producers. But in high-urban areas with large volumes of vehicular traffic and reduced wind speeds it might be wise to avoid trees that produce a lot of isoprene.

So how can we know which trees to plant and which to avoid? You can refer to a long list of trees and their ‘ozone-formation potential’ (OFP) in Landscape Architecture Graphic Standards, in an article written by Terry Gillespie and me. But here’s a shorthand version of the list:

  • Four genera with high potential to produce smog: Carya, Populus, Salix, and Quercus.
  • Three genera with low potential to produce smog: Acer, Fraxinus, and Tilia.

While it would be incorrect to say that trees actually cause smog, it certainly is correct to say that some trees contribute to the level of ozone smog in urban areas. We hope that trees will live for many decades, and while we don’t know what the level of nitrogen oxides will be in the future, it’s probably wise to use low OFP trees in high-urban areas.

Hopper, Leonard J. 2006. Landscape Architecture Graphic Standards. John Wiley & Sons, New York.

 

Driverless cars might be the answer to urban heat islands: Two lessons for landscape architects

It might seem like a futuristic idea, but it’s beginning to look like driverless cars are here to stay. Imagine having your driverless car take you downtown to shop. There’ll be no need to look for a parking spot. You can simply step out of the car and tell it to drive somewhere and wait for you to call it back. It could go home and wait in your garage, go to a designated parking area outside the urban core, or better yet, it could be a shared car and you could let it transport someone else around while you’re shopping. If cars no longer need to be parked near a destination it could mean the beginning of the end for those expanses of hot asphalt in the centres of our cities. There would be no need to park in the urban core. If this land was converted to almost any other use it would reduce the intensity of the urban heat island. But if the land was converted to well-watered, shady green space, urban heat islands might be converted to urban cool islands. An energy budget analysis helps to explain the reason for this transformation. Let’s first compare the effect of solar radiation falling on an asphalt parking lot and an expanse of grass. Solar radiation is either reflected or absorbed by a surface depending on its colour. Black asphalt absorbs a greater proportion of the solar radiation that it receives than does green grass. The energy absorbed by the surface is then converted into various streams of energy. If the surface is wet or transpiring, like the grass, then a lot of the energy will go into evaporation. But if the surface is dry like the asphalt then this stream is not available. All the energy absorbed by the asphalt goes into heating the asphalt and then either heats the air next to it through convection, or is emitted as terrestrial radiation. Both of these streams of energy help to create the urban heat island – warmer air and more terrestrial radiation. Meanwhile, the grass, having started with less energy, and then having lost some to evaporation, has much less energy available to heat itself or the air next to it, or to emit as terrestrial radiation. Cooler surfaces translate into less of an urban heat island.

Now let’s add trees to both landscapes and consider the effect. Instead of the solar radiation falling directly on the surfaces much of it would be intercepted by the leaves and branches of the trees. The radiation that makes its way through the canopy would then be transformed in the same way as the radiation in the previous example. The only difference would be that there would be a lot less energy to start, and the effect on the urban climate would consequently be much less. Even parking lots will stay reasonably cool if they are shaded by healthy trees.

Road, grass, trees June 19, 2014Here’s a thermal image of an asphalt surface beside a park with grass in the foreground and trees in the background. Using the scale along the right-hand side of the image you can ‘see’ the hot asphalt (pink and white), the cool grass (yellow), and the very cool shade of the trees (blue).  Some of the grass in this image is quite dry, so is not as cool as the well-watered grass and appears as a blotchy red/yellow pattern.

Sugar Maple shade thermalThe second image is of an asphalt surface that is partly in the full sun and partly in the shade of a tree. The shaded area (dark blue)  is much cooler than the area in the sun (pink and red).

Using this information there are two things you can do to help reduce the urban heat island in your city.

Lesson One: Plant trees that shade asphalt surfaces to reduce the effects of urban heat island intensification.

Lesson Two: Prepare for a future of driverless cars by starting to think about transforming parking lots into well-watered, shady green spaces.

Who knows… maybe we can unpave parking lots and put up a paradise.

 

Read more about energy budgets in Microclimatic Landscape Design by Robert D. Brown and Terry J. Gillespie, chapter 3, pages 45-63.

Driverless cars might be the answer to urban heat islands: Two lessons for landscape architects

It might seem like a futuristic idea, but it’s beginning to look like driverless cars are here to stay. Imagine having your driverless car take you downtown to shop. There’ll be no need to look for a parking spot. You can simply step out of the car and tell it to drive somewhere and wait for you to call it back. It could go home and wait in your garage, go to a designated parking area outside the urban core, or better yet, it could be a shared car and you could let it transport someone else around while you’re shopping. If cars no longer need to be parked near a destination it could mean the beginning of the end for those expanses of hot asphalt in the centres of our cities. There would be no need to park in the urban core. If this land was converted to almost any other use it would reduce the intensity of the urban heat island. But if the land was converted to well-watered, shady green space, urban heat islands might be converted to urban cool islands. An energy budget analysis helps to explain the reason for this transformation. Let’s first compare the effect of solar radiation falling on an asphalt parking lot and an expanse of grass. Solar radiation is either reflected or absorbed by a surface depending on its colour. Black asphalt absorbs a greater proportion of the solar radiation that it receives than does green grass. The energy absorbed by the surface is then converted into various streams of energy. If the surface is wet or transpiring, like the grass, then a lot of the energy will go into evaporation. But if the surface is dry like the asphalt then this stream is not available. All the energy absorbed by the asphalt goes into heating the asphalt and then either heats the air next to it through convection, or is emitted as terrestrial radiation. Both of these streams of energy help to create the urban heat island – warmer air and more terrestrial radiation. Meanwhile, the grass, having started with less energy, and then having lost some to evaporation, has much less energy available to heat itself or the air next to it, or to emit as terrestrial radiation. Cooler surfaces translate into less of an urban heat island.

Now let’s add trees to both landscapes and consider the effect. Instead of the solar radiation falling directly on the surfaces much of it would be intercepted by the leaves and branches of the trees. The radiation that makes its way through the canopy would then be transformed in the same way as the radiation in the previous example. The only difference would be that there would be a lot less energy to start, and the effect on the urban climate would consequently be much less. Even parking lots will stay reasonably cool if they are shaded by healthy trees.

Road, grass, trees June 19, 2014Here’s a thermal image of an asphalt surface beside a park with grass in the foreground and trees in the background. Using the scale along the right-hand side of the image you can ‘see’ the hot asphalt (pink and white), the cool grass (yellow), and the very cool shade of the trees (blue).  Some of the grass in this image is quite dry, so is not as cool as the well-watered grass and appears as a blotchy red/yellow pattern.

Sugar Maple shade thermalThe second image is of an asphalt surface that is partly in the full sun and partly in the shade of a tree. The shaded area (dark blue)  is much cooler than the area in the sun (pink and red).

Using this information there are two things you can do to help reduce the urban heat island in your city.

Lesson One: Plant trees that shade asphalt surfaces to reduce the effects of urban heat island intensification.

Lesson Two: Prepare for a future of driverless cars by starting to think about transforming parking lots into well-watered, shady green spaces.

Who knows… maybe we can unpave parking lots and put up a paradise.

 

Read more about energy budgets in Microclimatic Landscape Design by Robert D. Brown and Terry J. Gillespie, chapter 3, pages 45-63.

Artificial turf look cool? Think again!

Newly installed artificial turf looks magnificent - like a well maintained lawn.  But as is so often the case there's a big difference between form and function.  It might look like healthy grass, but it functions more like an asphalt parking lot when it comes to microclimate. Everything on earth emits terrestrial radiation based on its temperature.  The hotter an object is, the more energy it emits. A fireplace emits a lot of terrestrial radiation and will warm you on a cool day.  In contrast, a cold window will not be emitting nearly as much radiation and standing near it will chill you.

A thermal camera takes pictures of objects' temperatures.  In the thermal image below, the truck and the asphalt parking lot are about 46C (pink) while the trees in the background are closer to 25C (yellow and green).   A person standing in the parking lot would receive a large amount of terrestrial radiation from the asphalt and truck and would, over time, become overheated.  Someone standing on the grass near the trees would be receiving a lot less radiation and would feel much cooler.

Asphalt parking lot jpegNow let's look at a thermal image of an artificial turf playing field taken on the same day at almost exactly the same time.  The temperature of the artificial turf is even hotter than the asphalt parking lot.  It's almost 48C!  That's hot enough to cook an egg.  And look at the real grass in the foreground.  It's about 25C. A person standing on the playing field would be receiving a lot of terrestrial radiation, while a person standing or sitting on the sidelines would be receiving a lot less.

Artificial turf playing field jpegThink about the implications for people using the field.  There are times when the heat from the artificial turf would be welcome - say late in the fall when it's cool or cold outside.  But during mid-summer when the air temperature and humidity are high and the sun is shining, the last thing you want is to receive additional heat.  You certainly wouldn't choose to play sports on a black asphalt parking lot on a hot summer day.

Spectators standing or sitting on the sidelines on real grass and in the shade of a tree would likely feel quite comfortably cool, even on a hot day.  But the athletes playing on the artificial turf would be generating internal energy, and this in addition to the hot, humid, sunny conditions would be enough to make them feel very warm or even hot.  The additional heat they receive from the artificial turf could put them over the top.

Many of the components of microclimate are totally invisible to the human eye.  We can't see the air temperature, the humidity, or the wind.  Fortunately we now have cameras that make the invisible terrestrial radiation visible.  Now there's no excuse for designing playing fields that are as hot as asphalt parking lots.

 

Asphalt parking lot

Hot Weather Ahead: Learn how to design outdoor spaces to improve thermal comfort.

Bari street 3 We've had a long cold winter and and cool spring, but it's bound to be getting hot soon.  And when it does everyone will be looking for outdoor places that feel cool.  If you can spare 30 minutes I'd encourage you to watch the webinar that I gave for Health Canada last summer.  It'll give you ideas about how you can design outdoor places so that they'll feel cool on those hot, sunny summer days.

Listen to the webinar and watch the slides at the following link:

http://webinars.cullbridge.com/ccho.html

Scroll down to the August 20 entry, and select "webinar recording".  The first half was presented by a colleague.  My presentation is in the second half starting at 32:20.

Patio Season Starts Earlier in My Backyard

Spring 2013 216 After a long cold winter it can feel wonderful to get outside and enjoy some spring weather. Want spring to arrive a little earlier in your backyard? The secret is to think about how your yard affects heat flowing to and from your body. If you’re in a location where you’re losing more energy than you’re receiving you’ll feel cold. But there are ways to design your backyard so that it provides a balance of the incoming and outgoing energy.

There are three ways to add heat to your body when you’re outdoors – work harder to warm up from the inside, move into the sun, or move near a warm surface. There are also three ways to lose heat – move into the wind, wet your skin, or move near a cool surface.

In early spring you’ll want to maximize the additions and minimize the losses. There are many ways that this can be done but as an example think about a sunny but breezy spring day when the air temperature is hovering near freezing. It might look beautiful outside, but in reality it would feel very cold. But not if you have a sun-catch. It’s easy to design – start by selecting a place that is open to the south so the sun can stream in during the middle of the day. Next put a windbreak on the westerly side of the space. Your local conditions might vary somewhat, but across much of the USA and Canada the winds on sunny spring days blow from the westerly directions. Slow this wind and reduce the cooling. And finally, try to add a dark-colored south-facing wall on the north side of the space so that it can become heated by the sun. A bench set against this wall will be a wonderful warm place to sit on cool spring days.

All the details can be selected to match your design style as long as the basic pattern is met. I call this the critical component design approach in my book “Design with Microclimate”. For example, in a naturalistic garden you could use vegetation or your house as the windbreak and a wooden fence as the south-facing wall.Island Press Figure 1

And in a modern style garden the walls could be covered in vines.

Island Press Figure 2

The same principles can be applied to a larger area as well. The elegantly simple design of the outdoor café below creates a very pleasant sun catch in which to linger and sip a leisurely espresso.

Island Press Figure 3

You’ll enjoy the warmth of your sun-catch every spring and as a bonus it’ll also provide a warm retreat on cool fall days.

 

This blog was originally published by Island Press at: http://ipfieldnotes.org/patio-season-starts-earlier-in-my-yard/