When Efficiency Isn’t Enough

We love efficient machines. The more work you can get from a unit of energy, the better. But at Harvest, the most efficient heat pump does not necessarily mean it’s best to heat or cool a home. This recent article from Wired, The Hunt for the Most Efficient Heat Pump in the World, reminds us how obsessing over energy efficiency misses other important things. 

The article takes a deep dive into how heating engineers work to make installing heat pumps more efficient. Self-proclaimed “SCOP chasers” (Seasonal Coefficient of Performance) try to eke out more heat from every kWh of electricity used over the course of a year. They tweak their machines in subtle and not-so-subtle ways in the race to see who can rank highest on the heatpumpmonitor.org leaderboard. Right now the highest SCOP score is 5 – delivering 5x more heat than energy used to run the heat pump.  

Nerding out on SCOP is like trying to break the sound barrier in the early days of aeronautics – it’s good fun, builds expertise, and drives some innovation – but it doesn’t get you to the moon and back.

Harvest was founded based on a core insight from our Head of Product (and co-founder) Pierre Delforge. At the Natural Resources Defense Council (NRDC), he realized we cannot dig our way out of the growing carbon bubble with energy efficiency alone. To truly decarbonize our stuff, he came up with a different formula: use the least amount of energy, from the cleanest source, at the right time. 

And thus the idea for Harvest’s Smart Thermal Battery™ for combined heating, cooling,  and hot water was born. 

The heat pump at the core of the Harvest system has a SCOP of 3.7. Pretty damn good, but not off-the-charts. Still, Harvest beats all other heat pumps on the thing that matters most: tons of carbon prevented from entering the atmosphere. It runs a high-efficiency heat pump during the day when electricity is clean and cheap, and relies on stored heat for when the grid is dirty and expensive. Compared to gas, Harvest cuts emissions around 90% and lowers monthly energy bills by up to 30%. Even compared to a standard heat pump system, we delete 40% more carbon.  

So if you’re looking for the best heat pump for your home’s heating and hot water, ask about SCOP for sure. But if the heat pump isn’t shifting the energy use to the cleanest times, you’re missing a big part of decarbonizing your home - and your life.