Air conditioning

A month into summer 2024, the vast majority of the U.S. population had already experienced at least one extreme heat wave, and millions of people were under heat alerts, with forecasts warning of more ahead. Death Valley hit 125 degrees Fahrenheit (51.7 Celsius) or higher for nine consecutive days in early July. Las Vegas broke its all-time heat record at 120 F (48.9 C). Days of 100-degree heat dried out the California landscapes, fueling wildfires there and in the Northwest. Oregon reported several suspected heat deaths. Globally, the planet had its hottest day in at least eight decades of recordkeeping on July 21 – and then broke the record again on July 22, according to the European Union’s Copernicus Climate Change Service. The extreme heat is part of a longer trend: Each of the past 13 months has been the hottest on record for that month globally, including the hottest June, the EU service reported in early July. It also found that the average temperature for t...

The heat wave that left more than 100 million people sweating across the eastern U.S. in June 2024 hit so fast and was so extreme that forecasters warned a flash drought could follow across wide parts of the region. Prolonged high temperatures can quickly dry soils, triggering a rapid onset drought that can affect agriculture, water resources and energy supplies. Many regions under the June heat dome quickly developed abnormally dry conditions. The National Oceanic and Atmospheric Administration’s hazard outlook map shows flash drought warnings in yellow and areas forecast to have a high risk of excessive heat in early July in red. NOAA Climate Prediction Center The human impacts of the heat wave have also been widespread. In Ohio and Pennsylvania, emergency room visits for heat-related illnesses surged. Several Massachusetts schools without air conditioning closed to protect kids and teachers...

A deadly heat wave gripped Asia for weeks in spring 2024, sending temperatures in India’s capital region over 120 degrees Fahrenheit (49 Celsius) in May. Campaigning politicians, news announcers and Indian voters waiting in long lines passed out in the oppressive heat. In June, hundreds of people on the Hajj, a Muslim pilgrimage to Mecca, Saudi Arabia, died in searing heat that reached 120 F (49 C) with high humidity. Most of the planet has suffered the dire effects of extreme heat in recent years. Phoenix hit 110 F (43.3 C) or higher for 31 straight days in summer 2023, and Europe saw unprecedented heat that killed hundreds and contributed to devastating wildfires in Greece. Mexico and neighboring regions were sweltering through a dangerous and long-running heat wave in 2024. Regardless of where or when a heat wave strikes, one pattern has been a constant: Older adults are the most likely to die from extreme heat, and the crisis is worsening....

Heat pumps can be used to both cool and heat homes. The 2022 federal Inflation Reduction Act provides financial incentives for installing one. SciLine interviewed Theresa Pistochini of the Energy Efficiency Institute and Western Cooling Efficiency Center at the University of California, Davis. She describes how home heat pumps work; how switching to a heat pump reduces your home’s environmental impact; and when to upgrade your heating, ventilation and air conditioning systems. Theresa Pistochini discusses how home heat pumps affect indoor air quality. Below are some highlights from the discussion. Answers have been edited for brevity and clarity. What is a home heat pump, and how does it work? Theresa Pistochini: This decades-old technology is similar to an air conditioner, but a home heat pump also contains a reversing valve that switches the direction the refrigerant flows when you want heating instead of air conditioning. In hea...

Picture two homes on the same street: one constructed in the 1950s and the other in the 1990s. There are no trees or other shade. The air conditioning units are identical, recently replaced, and operating perfectly. Identical thermostats are set at 82 degrees Fahrenheit (27.8 Celsius). When it’s 110 F (43.3 C) outside, the 1950s house will likely feel at least 10 F (5.6 C) warmer inside, even with the same air temperature. Why? The answer has to do with radiant heat. Radiant heat is what keeps you toasty warm at a campfire on a cold winter night. The fire doesn’t warm the air much; rather, like the Sun, most of the fire’s heat moves through invisible waves directly from the campfire to your body. In the radiant heat of the Arizona sun, the surface temperature of the uninsulated post-and-beam ceilings in my house, one of 41,000 built in Tucson during the post-World War II era, can reach over 100 F (37.8 C). The single-glazed steel windows register 122 F (50 C...