Intro
Hello, ladies and gentlemen, welcome to another episode of the ARE Study Guide Podcast. Today we are going to talk about Passive Design Strategies! These first few episodes are all about the Programming and Analysis test, so this is going to be about the initial analysis of passive design strategies. This isn't going to be the nitty gritty on sustainable design, but just the initial site planning stage of things.
Climate Zones
So, to talk about passive design strategies, we need to talk about climate. The US Department of Energy has a very detailed map of climate regions that's used in the International Energy Conservation Code (IECC). [See: https://www.energy.gov/eere/buildings/maps/building-america-climate-specific-guidance-image-map]
We’re not going to get that specific because for the initial site planning, you don't really need to be that specific. So for this, we're going to look at four climate regions for America. They are: Cool, Temperate, Hot-Arid, and Hot-Humid.
Design Strategies By Climate Zone
Cool Climate: all of Canada, Alaska and the Northern middle part of America, Wyoming, Colorado, and Maine.
Cool Climate Design Strategies: compact building forms with minimal exposed surface area. This is going to help the building retain heat, minimize the surface area of the building with a cubicle shape or partially underground. Use materials with high thermal mass. Have the exterior of the building be dark or medium-dark colored so that it'll absorb heat. Maximize the solar radiation by having large windows on the south facade for the windows on the south facade. Make sure to provide shading during the summer, but allow the sun to enter in winter so you can do this with overhangs that stick out just enough to block the higher angle of the sun in the summer. Use deciduous trees because the trees will be full of leaves in the summer to block the sun and they will lose their leaves in the winter to allow the sun in. On the East and West facades you're going to want to have smaller windows. You're going to want to minimize the amount of surface area or opening on the Northern facade. You're also going to want to look at the wind patterns and make sure that you are minimizing the exposure on when word facts, especially if that wind direction is prevalent in the winter. Ideally, you would place the building entrance on the south facade where the snow can melt the fastest.
Temperate Climates: the vast majority of America, running like a band across the central part of America from Northern California to the Northeast Coast.
Temperate Climates Design Strategies: You're going to want to maximize solar exposure during the winter and maximize shade in the summer. Keep the Northern exposure minimal as the heat lost during winter and temperate climates can still be significant. Have medium colored buildings so they absorb some heat but not too much in the summer. Maximize the Southern exposure to collect heat in the winter. Provide shading in the summer. For the Southern facade, deciduous trees and overhangs again will be a great way to allow the sun to enter in winter and block the sun in the summer. Reduce the impact of the wind in the winter, but in summer you're going to want to allow for air circulation, especially at night.
Hot-Arid Climates: the southwestern States extending from Southern California to southwest Texas
Hot-Arid Climate Design Strategies: maximize shade and minimize hot dust-laden wind. So, you do want ventilation, but you have to be aware that in these hot, dry climates, wind often is carrying a lot of dust. So if that's the case, you want to minimize the exposure. You want to have small shaded openings. Compact building forms with minimal surface area. Cross ventilation is going to be very desirable at night to help remove the heat that's built up in the building during the day. Have light colors for your building’s exterior. Because hot air climates are so dry, any evaporative cooling methods will be great, so roof ponds are a great strategy for one or two story buildings because roof ponds will provide evaporative cooling and they also have a high thermal mass, you can also use mechanical evaporative coolers. Evaporative coolers can increase the humidity and decrease the air temperature. Hot-arid climates typically have large diurnal temperature swings, making thermal mass a great passive solution. Materials with high thermal mass will store heat during the day, keeping the building cooler and then at night, when it cools down, the thermal mass will release the heat to warm the building.
Hot-Humid Climates: Hawaii and the southeastern United States, up through Virginia.
Hot-Humid Climate Design Strategies: Your number one priority is going to be wind. Cross ventilation is always going to be desirable. Cross ventilation is going to remove the heat and increase the rate of evaporation, increasing the thermal comfort. To promote natural ventilation design open building forms that are narrow with high ceilings and large windows. Porches and breezeways can also promote airflow. The second priority is going to be shading. All openings should be shaded to have protection against solar heat gain. The high levels of humidity will minimize the daily temperature swings, making thermal mass and ineffective solution for hot-humid climates. Hot-humid climates are very hard to cool without using mechanical systems. Building should be light colored to reflect the sun. If possible, avoid water features or lots of vegetated areas as these will increase the humidity of the site.
Building Orientation
Now we're going to talk about building orientation. Generally speaking, a building should be oriented with its length running along the site’s East-West axis.
If the building site is located on a hill or mountainous region, that will also affect where you should place the building. In Hot-Arid climates, you're going to want to place the building at the bottom of the Hill to receive the cold air flow at night, and preferably on the Eastern face of the slope so that it can avoid solar exposure in the afternoon.
In Cool climates, you're going to want to place the building low, but not so low because you don't want it to catch that cold air that's in the Valley at night. But you also don't want it to be up higher where it's going to receive more wind. Ideally in a cool climate, you would place the building on the south facing slope to collect solar radiation.
In Temperate climates, buildings should be placed in the middle-upper part of a hill, so it has access to wind and solar radiation, but still protected from the very high winds that are usually at the top of the hill.
In Hot-Humid climates buildings should be placed at the top of a hill to have exposure to wind and ideally placed on the Eastern slope to decrease the amount of solar exposure it receives in the afternoon.
Conclusion
So for Programming and Analysis, that's pretty good rundown of the passive design strategies that will be tested. I hope this has been helpful. I am brand new to doing this, so I'm sorry if I stumble. If you have any feedback or any advice for me, I would love to hear it. Visit my website AREStudyGuidePodcast.com and you can reach out to me there. If you're interested in getting more information for the Programming and Analysis test, I wrote a study guide. That's where I'm getting this information from. There's a lot more information in my study guide. If you want to purchase it, you can check out my website. Again, I hope it was helpful. I hope you enjoy the rest of your day and happy studying!