Why Your San Francisco Home Still Struggles on the Few Hot Days We Get

San Francisco does not get many 85-degree days, which is exactly why so many homes handle them badly. Most Victorians and Edwardians here were built with steam or gravity heat and zero provision for cooling, so when a rare heat spike rolls in off the valley, homes with a single window unit or no cooling at all overheat fast, especially on upper floors and in rooms facing west.

Understanding why San Francisco's housing stock was built this way starts with the city's natural climate, which Wikipedia describes as one of the most temperate in North America thanks to cold Pacific Ocean upwelling and near-constant marine layer influence. For most of the 20th century, the city simply did not need air conditioning, so builders did not include it.

The most common fix we install today is not central air. It is a ductless mini-split heat pump. It requires no ductwork, handles both the occasional heat spike and the far more common damp, chilly evenings, and fits the electrical service most older SF homes already have.

If your home turns into a greenhouse on the handful of warm days each year, or one room is always ten degrees off from the rest of the house, the current setup was likely never sized for the microclimate you are in. That is a fixable problem with the right equipment and proper sizing. Learn more about our San Francisco HVAC services or read our short history of air conditioning in San Francisco to understand why this situation is so common here.