Answers to frequently asked questions regarding a property’s Heat Factor, the cost of heat, and health risks associated with increasing temperatures. 

Heat Factor is a free online tool created by First Street that makes it easy for Americans to find their property’s exposure to extreme heat events and understand how heat effects will change over time due to changes in the environment. As global temperatures rise at the fastest rates ever recorded, it's important to understand what factors contribute to heat risk. Use Risk Factor to find property-specific heat risk assessments determined by our heat methodology for any U.S. address.

What is Heat Factor?

A property's Heat Factor is an indicator of its risk of extreme heat exposure over the next thirty years.  The model assigns each property a Heat Factor, ranging from 1 (minimal risk) to 10 (extreme risk). Heat Factors are based on the current average daily high temperature and humidity of a property’s specific location, and how much the average daily high temperature and humidity in that location is expected to grow over the next 30 years. The expected change in average high temperature is influenced by the changing environment. A changing environment means higher average temperatures and increased humidity, which has a compounding effect on heat indexes that make risky health impacts more likely. As the global temperature rises at a faster rate than at any point in the planet’s geological record, it is important to understand what factors contribute to heat risk. Learn more about the environmental factors increasing heat risk.

How accurate is Heat Factor?

The peer-reviewed First Street Heat Model is a first-of-its-kind, nationwide, spatial temperature model that shows the exposure of a specific location to extreme heat events based on the temperature, topography, land cover, and humidity in the surrounding area. The development of the model required an unprecedented partnership with top climate scientists and modelers from leading organizations along with top data scientists and technologists to ensure the data is accessible, accurate, and actionable. 

Where possible, data has been validated against historic temperature records and government records. All methods used by the First Street Extreme Heat Model have been submitted to scientific peer-review journals.

How can I remove a property from Heat Factor?

Heat Factor is a product of the First Street Foundation, a non-profit committed to making climate risk information free and accessible to all.  We are committed to the accuracy of our data and we’re continuously working to refine our Extreme Heat Model methodology and incorporate new information into Heat Factor. When additional information is submitted, it is reviewed, and if appropriate, incorporated into the model, and shown on Heat Factor during a scheduled update. 

However, Heat Factors are not assigned on a one-off basis, rather they’re derived from the inputs that go into our Extreme Heat Model. These inputs come from publicly available data, therefore, properties cannot be removed directly through Heat Factor. Therefore, the only way a property’s Heat Factor can change is if new information is submitted that changes the underlying inputs used in our Extreme Heat Model. We encourage you to share information that may impact the inputs used in our heat by submitting an email.

How often is Heat Factor updated?

The Risk Factor team is continuously working to refine the Extreme Heat Model methodology and incorporate new information into Heat Factor. While the Heat Factor experience is updated regularly, a full Extreme Heat Model refresh occurs annually. Sign up for our newsletter to learn about updates as they become available.

What are heat islands? 

Heat islands are urban or metropolitan areas that are much warmer than the surrounding area due to human activities. The temperature difference is usually larger at night than during the day, greatly increasing the cost of cooling for homes and businesses located in a heat island. Nevertheless, daytime temperatures within a heat island can vary by as much as 7 degrees from the surrounding neighborhood or area. Common causes of the heat island effect include; neighborhood construction materials, city planning, and layout, distance to water bodies and vegetation, and human activities. Learn more.

How can I reduce my risk? 

Heat-related illnesses are caused by water loss,  excess physical activity, and reduced nutrients which causes your core temperature to rise. Being prepared will allow you and your loved ones to remain safe during extreme heat events. Before an extreme heat event, learn how to recognize and prevent heat-related illness.

To mitigate the negative effects associated with exposure to extreme heat, explore heat solutions such as energy-efficient ways to prepare your home for the next heat wave. Making the right investments to protect your home can protect you from dangerous heat illness on extremely hot days.

How much can heat cost? 

The amount of energy required to cool a home depends on the number of cooling days estimated for a property and the degrees of cooling required to maintain a consistent indoor temperature. The number of cooling days refers to the number of days when the temperature is warmer than 70°F and therefore requires the use of air conditioning to maintain a comfortable indoor temperature. The warmer the temperature outside the greater degrees of cooling required. 

The cost to cool a home depends on the temperature outdoors and specific property characteristics such as the number of bedrooms, age of the home, and square footage. The price each household will pay for electricity varies depending on where the local grid is supplied, the companies that supply an area, and the number of homes. Using data on energy rates from Energy Information Administration (EIA), a property’s yearly energy consumption is translated into cost based on energy rates in that area. Learn more.

Please note, cooling days on Risk Factor only consider air conditioning, not other cooling devices such as fans

How can heat affect health?

Extreme heat can lead to dehydration, fatigue, heat stroke, heat exhaustion, and heat cramps, which occur as a result of the body’s inability to cool itself relative to the surrounding environment when heat indexes exceed certain physical thresholds. Heat Index Values are a measure of how hot it feels outside when incorporating relative humidity. 

Heat Index temperatures around 80 degrees are associated with relatively minor consequences, such as fatigue. Once the heat index exceeds 90 degrees, heat-related illnesses such as cramps, heat exhaustion, and heat stroke become possible. At a heat index of 100 degrees, early-stage heat-related illnesses such as cramps and heat exhaustion go from being possible to being likely for anyone who is exposed to heat for a prolonged period of time.  While heat-related illnesses can cause death at any heat index, a heat index above 125 degrees is particularly risky. At these temperatures, heat stroke is likely to occur for any individual exposed to these temperatures for a prolonged period of time. Learn more.

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