At YR Architecture + Design we’re a big proponent of taking advantage of the earth’s natural resources to help improve and regulate the spaces we inhabit. Taking advantage of these free resources in designing homes and buildings brings numerous benefits from cost-savings to improved comfort to health benefits, not to mention it’s a sustainable strategy.

As a precursor to sharing key strategies to help you design your house to respond to the sun, it’s important to understand the fundamental building blocks of passive solar design.

This post is an introduction to those fundamentals and is the first in our series: Designing Your House to Respond to the Sun.

Today’s post covers:

  • Solar orientation
  • Sun angles and sun paths
  • (How-to) Determine sun angles for your location
  • An intro to passive solar design

In later posts, we’ll build on these concepts as we discuss the ways to incorporate passive design into your project. But for now, let’s learn the basics.

 

An Intro to Solar Orientation

Solar orientation is the positioning of a site, building, or space in relation to cardinal directions and, more importantly, the sun’s path. Whether it’s your site, your home, or even a specific room in your home, everything has a specific orientation and relationship to the sun’s movement across the sky.

Solar orientation: The sun

The azimuth angle is the horizontal angle measured from due south. The greatest angle would be on the horizon at sunrise/sunset. 

The altitude is the vertical angle above the horizon. The highest angle would be due south at midday. 

Solar Orientation: Azimuth angle & Altitude angle

 

 

(How-To) Determine the Sun Path and Sun Angles for Your Location

Every geographic location has a slightly different sun path. Once you know how the sun moves across the sky, you can plan and design your house to respond to that movement any day of the year and any time of the day.

So to start, I encourage you to learn the sun path and sun angles for your city as you embark on your own design process. This will help you later as you incorporate various passive solar strategies into your home design.

For a quick and easy way to find the altitude of the sun at its highest point on the solstices where you live, do this quick calculation:

  1. Look up your city’s latitude
  2. Subtract your latitude from 90° to get your Equinox
  3. Sun angle at summer solstice = Equinox + 23.5°
  4. Sun angle at winter solstice = Equinox — 23.5°

How to determine the altitude angles for your location

Here are a few of our favorite resources for sun path data:

1. Andrew Marsh’s Sun Path Application

This is our favorite way of getting sun path information including sun angles, azimuth, sunset and sunrise times and a whole bunch of other information for any geographic location. Plus, it’s super easy: Just enter your geographic location and select what data to display.

Sun path diagram

 

2. Sun Angles Tool by Sustainable by Design

This resource is slightly more involved but the data is more exact:

Here are the steps:

  1. Enter your zip code (then click lookup)
  2. Enter the date and time (You’ll do this 4 times – noon and sunrise on June 21 & Dec 21)
  3. Hit calculate.
  4. Under the outputs, find the following sun angles:
    A. Altitude angle at noon
    B. Azimuth angle at sunrise/sunset

Sustainable by design: Sun Angles Calculator

Note: There is a difference between true (solar) south and magnatic south of approximately 23.5 degrees (equal to the Earth’s tilt on its axis). This is due to the molten core of the Earth moving around, along with ore deposits in the Earth’s crust, and is referred to as solar declination. You want your home to follow the true directions, not the magnetic directions.

 

3. Sun Seeker App for mobile devices

Available for android and IOS for a small fee, this augmented reality app shows the sun’s path throughout the year for any location and is in real time. It’s a really cool app that let’s you see the Earth’s location by holding it up in the air and aiming it in different directions.

Sun Seeker App screenshots

 

 

Sun Angles for Columbus, OH

With your sun angles, you can start to visualize what the sun path looks like for your location. Here’s what the sun path and angles look like for Columbus, OH.

Sun Angles for Columbus, OH

In the winter, notice that the sun does not rise due east but rather south of east at 58 degrees from due south. This is the azimuth angle. As it moves across the sky throughout the day it forms a low arc. At its highest point at noon, it only gets to 26 degrees above the horizon. This is the altitude angle. Like at sunrise, the sun does not set due west but rather south of west again at 58 degrees from due south.

In the summer, the sun rises 121 degrees from due south, moves across a higher arc at a max angle of 73 degrees above the horizon at midday, then sets again 121 degrees from due south.

Once you determine your azimuth and altitude angles, you’ll use this information to start to design your home to respond to the climate and movement of the sun, ultimately helping you take big strides to create a more sustainable home (and one with smaller utility bills!).

 

What is Passive Solar Design?

You know the orientation of your site and where the sun will be at any given time. Now, you can design a home that will let the sun in when you want it to come in (in the winter) and keep it out when you want to keep it out (in the summer). What you’re trying to do is regulate the temperature inside and out of your home naturally so that you can become less reliant on mechanical and electrical systems.

This is what passive solar design is all about: Designing your house to do as much as it can to heat and cool your house on its own.

It’s a passive approach, meaning it’s low-tech and does not rely on mechanical devices or operations to function, unlike active HVAC systems that use fans, pumps, and electrical components.

Passive solar design is about collecting, storing, distributing, and/or controlling solar energy (both heat and light) so that you can reduce your demand on fossil fuels. This passive approach means that through the basic elements of the house–its walls, windows, floors, and roof–and through its relationship with the surrounding site, the house is able to inherently respond and optimize solar energy, whereby increasing the energy efficiency of your home, making it more comfortable to live in, and being cheaper to run.

 

Passive solar design works in three ways:

1. Direct gain systems: heat spaces via direct solar gain through glass

Solar orientation: Direct gain

2.  Indirect gain systems: heat a part of a building like a thick wall or concrete floor then rely on conduction to slowly transfer heat to space over time, aka thermal mass

Solar orientation: Indirect gain

3. Isolated indirect gain systems: heat an adjacent space then rely on convection to transfer heat to other spaces, aka sunrooms

Solar orientation: Isolated indirect gain

To further demonstrate how various building components contribute to passive solar design, here are a few quick examples.

Collect: A space collects heat/light when solar energy passes through window glazing.
Store: A thermal mass absorbs, stores, and distributes heat at a delayed rate to help regulate and control room temperature.
Distribute: Through radiation, convection, and conduction heat is distributed through the house.
Control: Light shelves, insulation, overhangs, and vegetation all help control by bouncing, blocking, filtering, and regulating the amount of heat and light that enter a space.

 

Passive Solar Design Is a Holistic Approach

So how do you use orientation in the design of your home? 

Designing a house to respond to the sun requires mindfulness and intentionality from beginning to end. It requires a whole system approach and starts with good project goals and a cohesive design concept. You can not simply focus on one aspect of your design (like sunshading) and think you’ve nailed it. You have to think holistically about the entire design. It involves all aspects of building design from site design to building design to building construction.

Starting early and being intentional in the big overall design moves (such as how you locate, size, and orient your spaces) will go a long way in making it easier to design a house to respond to the sun.

Once you get the big design moves figured out, the smaller essential considerations become a little easier to manage and account for. The building shape and room configurations affect how much light and heat can penetrate the house as well as which rooms will receive the most sunlight and heat gain. Locating certain less frequent rooms on the north face can open up views and sunlight to the south; great for passive solar design if shaded properly.

Every design decision has ripple effects and lasting impacts.

Conclusion

There’s a lot to think about when it comes to designing a house to respond to the sun. This is where architects and designers can add a lot of value to your project. We have experience in creating homes that not only respond to the sun but that look elegant and timeless–where the passive design strategies often go unnoticed. We’ve learned to take a whole system’s approach to design so that the final result is cohesive, functional, and beautiful.

If you’d like help in incorporating passive design strategies on your project or want us to review your current project, please contact us. We’d love to help you!

 

But if you’re doing this on your own, here’s the advice we would give you:

To effectively design a house to respond to the sun, start with the big overall passive design strategies first and then work your way down to the smaller ones.

If you’re asking ‘what are these passive design strategies’, ‘which ones are the big ones’, and ‘how do you effectively design a house to respond to the sun’? Stay tuned to our next post!