Here’s the thing: unchecked climate change will wipe out human civilization through food chain collapse, mass migrations, sea level rise, and lots of other bad stuff. But you already knew that. And you know that the warming comes from our emissions of CO2, which means we must stop burning the gas and oil we use to heat our homes and convert to electricity from carbon-free sources. You also probably know that New York City has officially decided to reduce greenhouse gas (GHG) emissions 80 percent by 2050.
But how do we do this? Up until now, electric heating consisted almost entirely of resistance heat (think an electric space heater or a toaster). But switching buildings to resistance heating would call for a huge increase in generating capacity, in addition to the in-building technology shift. But wait! Resistance heat is not needed! Heat pumps can provide the same amount of heat for one-third the electric energy because they move heat from a cold place (outdoors) to a warm place (indoors), rather than just converting electric energy to heat. Heat pumps also provide summer air conditioning.
Critics complain: We can’t replace boilers with heat pumps all over New York! Heat pumps are complicated machines, they make noise, they take up space, they cost money, and worst of all, they’re different from what we do now. It just won’t work.
Well, actually, yes it will—and it’s already happening. It's Electrifying: Converting Heating Systems, Urban Green’s second panel on how New York City could electrify its buildings, featured three top practitioners of efficient, affordable building improvements. Moderator Mike Brusic of Bright Power opened the evening by presenting the enormity of the task: according to NYC studies, we must lower GHG emissions from buildings by 46 percent from 2005 levels to reach 80x50. Space heating uses 36 percent of source energy in NYC buildings, and with over three million housing units in NYC—and “only” about 20,000 new units being built per year—we must attack existing space heating systems, especially steam, head-on. But how?
Ian Shapiro, founder of Taitem Engineering in Ithaca, presented “Heat Pumps 101,” starting with a brief history of the growth of heat pump installations in his home county, Tompkins, over the past decade. From 2005 to 2009, only 21 units were installed. From 2010 to 2014, 138. And from 2015 through September 2017, 859! The county has just shy of 40,000 housing units, so as of now, something like 2.5 percent of the heating systems are heat pumps. This came out of nowhere, in just ten years.
Shapiro then explained which types of heat pumps are useful in which applications (plus scads of other useful information). I’ll hit three highlights here: First, the new generation of heat pumps will work effectively anywhere in New York State without backup resistance heat. Second, he found that heat pumps use 36 percent less energy than steam heat (which, in addition to burning fossil fuels, is inefficient). Third, for at least the next decade, meeting space heat loads with heat pumps will fill a wintertime “valley” in state-wide electric power demand, which is now characterized by a summer air-conditioning peak. He added that we’ll have a winter nighttime peak load issue by 2050.
The presentation then switched to a panel discussion, with Brusic posing questions to Shapiro, Joe Novella (Green Star Energy Solutions) and architect Mark Ginsberg. The real takeaway is that the discussions reported below follow from actual practice: heat pumps are being installed and retrofitted today, and these projects will serve as the examples used to convince doubters tomorrow.
Of course, the gorilla in the room was that while heat pumps may work well on low-rise buildings, they have not been extensively proven in large buildings in NYC, which have many stories and complex heating and cooling loads. Shapiro reassured us that heat pumps could meet the challenge through the careful selection of equipment types, chaining multiple units, and locating equipment on roofs. Ginsberg discussed problems that have arisen in installations in a city where buildings are designed to within an inch of the property line, leaving no room for external wall-mounted compressor units or, in some cases, even tubes. Novella cited examples of retrofits to large mixed-use buildings, but he has not seen any pure large residential installations. He wants to gather more examples of different types of systems, the better to convince doubters.
Brusic raised the heat pump/envelope issue: better envelopes lower heating and cooling loads, which permit smaller and less expensive heating and air conditioning systems, whether those are heat pumps or standard types. Ginsberg pressed for wrapping buildings like NYCHA’s towers to provide insulation and air sealing; Novella spoke out for heat recovery ventilation. Shapiro praised envelope work but argued that, in most cases, one can simply install heat pumps and still meet current heating loads.
One reason current loads can be met with refrigerant-to-air units in the living space is that the available indoor units are oversized for heating or cooling a single room. But as soon as a panelist shared that the smallest unit available was 3000 Btu/hr, a manufacturer’s rep in the back of the room yelled “2000!” We just hope they keep scaling down, even though current units have good modulating capacity.
Aren’t heat pumps more expensive to operate? No, and yes. Upstate, 10¢/kWh electricity gives plausible payback periods based on operating cost savings. In NYC, 20¢/kWh electricity does not. Someone complained about the low price of fracked gas. Ian Shapiro called for a carbon tax. No one disagreed, but no one expects carbon pricing anytime soon. In the meantime, upstate will most likely lead the way on heat pump conversions.
So, heat pumps are the path to an electrified future for space heat. But even in that future, we’ll need to keep clean and wash dishes—where will the hot water come from? Our next presentation, The Future of Domestic Hot Water in NYC, on February 6th, will explore the options for efficient production of domestic hot water with electricity and will find us, once again, discussing heat pumps.