What is Your Building’s Sun Number?

3661 Last modified by the author on 25/05/2022 - 12:25
What is Your Building’s Sun Number?


The sun is more than just a source of light during the day. It’s the first step in the chain of energy that drives life on planet Earth. Plants rely on the light and heat of the sun to create the nutrients they need to grow. Animals eat these plants, using the sun’s energy in a new form. Without the sun, life would be completely wiped out.

People have relied on the sun’s energy since the beginning of time. They’ve harnessed its heat to cultivate and preserve food and to stay warm throughout the year. In both literature and oral traditions, the sun represents constancy and hope – the promise of a new day and a fresh start. Removed from human influence, the sun will rise and set the way it always has.

For thousands of years, people have experimented with the sun’s energy to create light and heat. As early as the 7th century B.C., there are records of people using solar magnification to light fires. However, it wasn’t until the late 1800s that the scientist Charles Fritts created the first solar cell using selenium as a photovoltaic conductor. Further discoveries in the 1900s led to the silicon solar panels that are marketed to homeowners today.

Solar panels present an exciting alternative to a reliance on fossil fuels. Once installed on your home, they can eliminate your energy bills while reducing your home’s negative impact on the environment.

Today, you can use your building’s sun number to determine whether solar panels are a good solution for your energy needs.

How Sun Numbers Work

Architectural sun numbers are a scoring system created by an environmental company, Sun Number, and Zillow, an online real estate marketplace. These numbers help consumers understand a property’s potential for harnessing solar energy.

Buildings are scored from 1 to 100 with higher numbers representing a better fit for solar energy. According to Solar Reviews, a number of 70 or above means solar panels could be a good investment for your property. As of early 2022, over 84 million homes listed on Zillow have a published sun number.

Unfortunately, you can’t filter Zillow homes by their sun number. However, if a home has been given a sun number, you can find it by clicking on the “Facts and Features” tab under a listing. Click “see more” and then scroll down. If the home you’re viewing has been rated, its sun number will be posted under the Utilities/Green Energy Details section.

Sun number ratings are a combination of four different scoring categories.

The first category measures the logistical capacity of a building to harness solar energy. This includes details like roof size, shading, and orientation. The second category considers regional climate and the amount of sunshine a building may receive to power solar panels.

The third and fourth categories assess the cost of traditional electricity in an area and the initial price of installing solar. Although initial costs can be high, solar panels pay for themselves in energy savings in an average of eight years. Taken together, these four calculations are meant to help homeowners assess whether solar power is a good fit for a specific property.

How to Find Your Building’s Sun Number

If your home has already been given a sun number, you can find it by looking at the listing on Zillow. For homes that aren’t on the market, you’ll need to click on the tab for “Owner Tools.” Scroll down to the “Facts and Figures” section and look for information on utilities and green energy. If your home has a predetermined sun number, it will be listed there.

As of December 2021, Zillow had over 135 million properties in its marketplace. Of these homes, at least 51 million have not yet been assessed for their solar energy potential or been given official sun numbers. Unfortunately, this means there’s a good chance you won’t be able to find your building’s sun number on Zillow.

However, your options don’t end there. Next, try exploring your neighborhood on Zillow to see if other homes are rated. If they are, you can look for properties with similar roof sizes and sun exposure to your building. You may be able to make a good estimate based on the sun numbers of surrounding properties.

If nearby properties haven’t been given sun numbers either, you can always call a certified contractor to assess your property’s potential for harnessing solar energy. You should get several quotes and assessments from different contractors. Only work with reputable, well-established companies to ensure you get an honest appraisal.

Ultimately, sun numbers are only one of many tools you can use to assess whether solar panels are right for you. Installation costs will vary depending on which company you use and where you live. You also need to consider how long you’re planning to stay in one place and how many years it might take to reap the benefits of investing in solar.

Sun and Architecture

The sun has played an important role in architecture throughout human history. Before air conditioning and heating systems, people built homes strategically so they’d be cool in the summer and remain warm in the winter. In the Northern Hemisphere, south-facing homes soak up heat from the sun and naturally retain heat year-round. In contrast, north-facing homes tend to stay cool inside despite varying seasonal temperatures.

Of course, building materials, window placement, and the surrounding environment all affect your home’s internal temperature too. The modern movement for building passive homes uses specific materials, building placement, and the sun’s warmth to reduce the cost of heating and cooling your home throughout the year.

Solar panels represent another way in which human beings can rely on the sun’s energy to build a better life. If you’re interested in switching from traditional energy providers to solar, you should check out your building’s sun number first. This number evaluates different requirements to determine whether your property is a good fit for solar.

Check the listing on Zillow or contact a local contractor to find out your building’s sun number. Although solar panels are usually a good investment, the initial cost of installing them is high. Before you consider switching to solar energy, it’s wise to do thorough research on this technology’s return. Your building’s sun number is one of many resources that can help you make an informed decision about switching to solar.

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Emily Newton