HEAT RISK

The last five years have been the warmest on record globally.

Both the annual average temperature and extreme temperatures have been increasing over the last several decades. By the 2070s, the average summer temperature is projected to increase by 6 to 10 degrees Fahrenheit, and there could be more than 60 days per year with maximum temperatures over 90 degrees. As heat waves become longer and hotter, heat will persist into the evening, with buildings retaining heat overnight and occupants suffering more from extreme heat exposure.

Extreme heat affects our health and our ability to function. Heat stress causes more deaths in the United States than any other climate-related event, including storms and hurricanes.

Heat stress occurs when environmental conditions overwhelm the body’s cooling mechanisms, and a healthy energy balance cannot be maintained.

Heat index is an index that combines air temperature and relative humidity to determine the “feels like” temperature that people experience. A sustained increase of internal body temperatures reaching 104 degrees can lead to heat stroke and death as identified in orange below in the NOAA heat index table.

Members of our community most at risk are elderly, very young, homeless, outdoor workers, people on certain medications, and people with medical conditions such as asthma or cardiovascular disease. 

Our neighborhoods have a relatively high proportion of older housing stock that may be poorly adapted to hot weather and lack air conditioning, making people at risk more vulnerable.

Rising temperatures will increase the need for cooling systems. By 2030, building cooling loads could double, and by 2070, cooling loads could be twice that of heating loads.

Cities are usually warmer than suburban and rural areas. This is a phenomenon known as the urban heat island (UHI). This effect makes hot days worse in cities and adds to the effect of climate change.

Cambridge has seen an increase in impervious, or impenetrable, surfaces and loss of tree canopy in the recent past that has increased the City’s UHI.

An interactive map of the City allows users to assess how much roof surfaces absorb heat from sunlight as measured by albedo, which is the proportion of the solar radiation that is reflected by a surface. Dark rooftops that have a low albedo absorb and give off more heat.

To find out how your building is performing, click below.

Maintaining a livable indoor air temperature and healthy buildings are essential to public health, therefore a building’s resiliency to extreme heat is a critical component of Resilient Cambridge.

Currently, the State requires landlords to maintain a livable temperature between 68 degrees and 78 degrees between September 15th and June 15th (heating season). There is no similar requirement for cooling. 

But as average temperatures become higher, the demand for cooling rises. Heatwaves are becoming more frequent and intense, increasing peak energy demand and risk for brownouts. Buildings will need to adapt to increased temperatures in several ways. Currently, there is no similar requirement for cooling.

Extreme heat can impact everyone.

The City of Cambridge developed resilience flyers to help you assess your risk. These flyers also provide steps for you, your home, or your business to prepare within 24 hours or less of an extreme heat event.

Planning for this "new normal" requires imaginative and responsive changes by the City and the community. Resilient Cambridge is substantive and optimistic and provides a comprehensive set of actions and strategies.

Click the button below to find out about the City’s Heat Strategies.