New hospital buildings can be designed to be Scope 1 carbon free by following these strategies:

1. Do not use any fossil fuels on site. You can't build a business-as-usual hospital and expect to get to zero carbon. Installing gas-fired boilers today locks in carbon emissions for the next 30+ years. Make the commitment up front to eliminate the use of fossil fuels - go all-electric and ride the curve of the power grid as it improves. This Guidebook offers a variety of strategies to help you meet this commitment.
2. Minimize loads. Building low-carbon systems is less expensive if you build less capacity. Focus on reducing cooling and heating loads. This Guidebook begins with load reduction strategies to reduce your investment.
3. Use Dedicated Outdoor Air Systems (DOAS) with energy recovery. In warm and humid climates, cooling energy associated with dehumidifying outside air can be 25% or more of the total cooling load of your chilled water system. Clinical space in hospitals is usually air-change driven, which means we're delivering more air than we need to cool the space - even a VAV system can only go as low as code allows. In humid climates, this drives us to overcool, then reheat to keep the space comfortable. Outdoor air for ventilation is the primary source of moisture that an HVAC system must manage, so handling ventilation separately from cooling can reduce both cooling load and the energy needed for reheat. Even in cold or dry climates, Dedicated Outdoor Air Systems (DOAS) that incorporate energy recovery are effective in reducing cooling and heating loads. Look to the Guidebook chapter on dehumidification.
4. Use an all-electric heating plant with heat pumps and heat recovery chillers. The benefit of electrification comes through the use of heat pumps, which use electricity to move existing heat rather than make new heat. An all-electric heating plant recovers heat from the building chilled water system. Heat pumps supplement heat recovery by pulling heat from other sources, such as thermal storage, wastewater, ventilation exhaust, and other energy flows that we normally think of as waste. Heat pumps and heat recovery chillers are essentially the same thing - they move heat from where we don't need it to where we do need it, by raising it to a useful temperature. Because they are transferring heat rather than creating it, they are 2.5 to 5 times as "efficient" as electric heat.
5. Use heat pumps to replace gas-fired boilers for domestic hot water. Heat pumps can also be used to heat water for domestic use - either as part of a heating hot water system, or as a dedicated water heating system.
6. Use single temperature hand washing to reduce first cost and energy use on DHW system. This means that all faucets in the building should dispense water at the same temperature, which can help to reduce the amount of energy needed to heat water.
7. Use thermal energy storage with renewable solar thermal energy and heat recovery for load shifting and handling nighttime heating challenges. When it gets cold enough outside (below 30 degF for most hospitals), there won't be enough heat in the building to overcome the losses of the building envelope and ventilation losses. You'll need to supplement heat recovery with another source. Thermal storage is one way to manage that load, and there are numerous options for thermal energy storage, including stratified tanks, phase change systems that make ice or that use a custom-blended material, and using the earth itself as a storage medium through ground-source heat pump or borehole thermal energy storage systems.
8. Use electric or adiabatic humidification. Except in the most humid climates, hospitals will sometimes need humidification is needed - typically in the winter. In the absence of a steam boiler, electric steam generators can provide a relatively economical source for humidification, but ASHRAE 170 recently approved the use of adiabatic humidifiers, which do not require a heating source, other than the air itself.
9. Use electric steam generation for sterilization. While electric generation is not necessarily lower carbon than gas-fired boilers, they make sense if your only steam load is sterilization. They have the added benefit of reduced maintenance and will ride the curve of the grid as it decarbonizes.
10. Consider solar thermal steam generators. Solar thermal steam generators can use solar energy to store heat in a thermal fluid, which is then used to create steam. While obviously a zero-carbon heating source, these systems can be costly to design and install.
11. Use low-carbon electrical energy sources, including on-site solar and wind, power purchase agreements with third-party renewable energy providers, or a microgrid that can use a variety of sources, providing the freedom to shift sources as costs change and new sources come available.