New York City is aiming for an 80% reduction in greenhouse gas emissions by 2050, taking the levels measured in 2005 as reference. Considering that most city emissions come from buildings, the 80x50 goal is only reachable with the collaboration of property owners. Space heating and domestic hot water (DHW) tend to have the highest carbon footprint among building systems, since they rely on fossil fuel combustion in most cases.
As long as heating systems use combustion, they will produce emissions no matter how efficient they become. Phasing out heavy heating oils is also a step in the right direction, and by 2030 only No. 2 will be allowed. No. 4 is already banned in new constructions and allowed in existing properties until 2030, while No. 6 is banned completely - an upgrade is legally required for buildings that still use it.
There are two main ways in which a building can get heat without emissions: using solar collectors, or using electric heaters that run on clean power.
- The issue with solar collectors is that they need rooftop area, which is limited in NYC compared with total indoor floor space. Also consider that their output is determined by sunshine, a variable input.
- Electric resistance heaters have a prohibitive operating cost, considering the high electricity prices in NYC. However, heat pumps deliver the same output for just a fraction of the electricity input, compensating the high price of electricity with efficacy.
Considering these factors, a viable strategy to reduce the carbon footprint of NYC is:
- Transitioning to heat pumps to reduce emissions at the building level.
- Deploying renewable generation to reduce emissions at the power grid level.
Air-Source Heat Pumps
The main problem with electric heating is cost: electricity tariffs in NYC exceed 20 cents/kWh, surpassing the US average (12.5 cents/kWh) by 60% or more. Conventional electric resistance heaters have a very high demand for power, which results in a prohibitive operating cost. However, heat pumps are a newer and more efficient technology, and they can be described in layman terms as air conditioners operating in reverse. For a given heating output, a heat pump consumes 2 to 4 times less power than a resistance heater.
An additional advantage of heat pumps is that they can be designed with a dual function, operating like a normal air conditioner during the summer. This way, you can consolidate heating and cooling into a single system.
A resistance heater converts electric power directly into heat, which means you need to consume one watt of electricity per watt of heating provided. On the other hand, a heat pump uses electricity to run an inverse refrigeration cycle - electricity is still converted to heat, but most of the heat delivered is drawn from outdoors.
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Air-source heat pumps (ASHP) are a specific type of heat pump that gets its name because it can extract heat from outdoor air, even when it is cooler than indoor air. There are also water-source and geothermal heat pumps, which extract heat from a body of water or from underground, respectively. However, you require very specific site conditions to use water-source or geothermal systems, so ASHPs are the most promising option for NYC buildings.
The New York State Energy Research and Development Authority (NYSERDA) has created an incentive program for ASHPs, where participating installers get an incentive of $500 per system. The total program funding is $10.95 million, with up to $500,000 per contractor.
Solar Power and Other Renewable Sources
Transitioning to electric heat pumps reduces emissions at the building, but there are still indirect emissions if the electricity comes from power plants fired by fossil fuels. However, if the electric supply is also decarbonized, space heating and domestic hot water can be free from both direct and indirect emissions.
The state of New York is not particularly sunny, but there are three factors that make solar power an attractive investment for property owners:
- Electricity is expensive, which drives up the value of each kilowatt-hour generated on site. Solar panels are viable for most buildings, unless the property is covered by shadows or the roof structure is inadequate for photovoltaic modules.
- The NY-Sun program offers excellent rebates for solar power, making them more affordable. In addition, households below the median income may be eligible for a double rebate.
- Four separate tax benefits: Solar photovoltaic systems are exempt from the property tax and the sales tax, while granting both federal and state tax credits. Getting four separate tax benefits for a single photovoltaic array is a very attractive incentive to deploy the technology.
In short, solar power systems are cheaper to own thanks to the rebates and tax benefits, while their output becomes very valuable due to the high electricity tariffs. New York is currently among the best states for the solar industry, even though sunshine is moderate.
Wind turbines are more demanding in terms of site conditions, but you can get incentives for them as well, assuming your property has suitable wind conditions. Keep in mind that wind turbines to not have the scale flexibility of photovoltaic panels; solar power is viable at both small and large scales, but the business case for wind power is significantly better for a single large turbine, compared with multiple smaller ones.
Since both solar power and wind power have a variable energy output, NY has established an energy storage target, as an initial step for increased renewable energy integration. Energy storage can balance variability, absorbing surplus production and covering gaps in demand.
To reduce the carbon footprint of NYC buildings, it is important to consider the energy supply chain, not just the building in isolation. Minimizing local use of fossil fuels is important, converting from combustion-based heating to electricity-based heating. However, if the power network continues to depend on fossil fuels, the emissions are just being moved elsewhere. To achieve zero emissions throughout the entire value chain, power sources must also become clean.
The state of New York has a Renewable Portfolio Standard requiring 50% of all electricity to be generated from clean sources by 2030. In turn, the 80x50 emissions reduction plan is an initiative specific to New York City.