Energy efficiency in individual buildings is the foundation of any zero energy district.
Investing in building-level efficiency reduces the amount of renewables needed to achieve zero energy while saving building owners and tenants money on utility bills.
With clear, practical, high-performance building guidelines in place for existing building owners, as well as the developers of new buildings, the zero energy district can more accurately plan ahead for energy needs and opportunities, saving infrastructure costs.
Different building types—such as multifamily properties, commercial office spaces, and industrial facilities—typically use varying amounts of electricity and heat at times of the day and week. This allows for synergized resource sharing among the varied building types.
For example, district level heating, ventilating, and air conditioning systems can be smaller because different building types peak at different times of the day, week, or year.
Additionally, these diverse energy needs allow the district to harmonize its interaction with the larger grid so that the collective system is more beneficial than the sum of its parts.
Solar photovoltaics are a common way to provide energy for a zero energy district. In addition to rooftop solar, community solar can provide solar energy in a district.
Community solar allows buildings that would not be able to achieve zero energy on their own—such as high-rise multifamily structures—to harvest energy from a shared community resource. That way, the entire district can achieve zero energy as a whole. It can also use energy from another building that has an excess.
With the entire community sharing the photovoltaics, rooftops, parking canopies, and large solar fields, all buildings can contribute to the common goal of zero energy.
Having districtwide heating and cooling systems offers many opportunities for resource sharing and resiliency.
Some buildings may run air conditioners while others use heat. And some building types—such as data centers—produce excess heat constantly. Supermarkets are another good example, since refrigeration creates heat that can be captured. A district thermal system allows waste heat from cooling in one building to be used for space heating or water heating in another building, improving overall energy efficiency and cost-effectiveness.
Additionally, because different building types use heat at various times of the day and week (leveraging diverse energy needs), overall system sizes can be smaller when multiple building types use the same thermal energy system.
Zero energy districts present opportunities for shared storage of both electrical and thermal energy.
Electrical storage offers many benefits. It allows for optimal use of solar resources across the district. It can also help ensure that the district is providing energy to the larger grid when and how it’s needed, potentially generating cost savings for owners. Some electrical systems can continue to provide service while disconnected from the larger grid. This capability is called “islanding.”
District thermal storage has similar benefits, optimizing thermal energy use among buildings by ensuring that energy is available where and when it’s needed. It can also significantly reduce heating and cooling costs for building owners, who can take advantage of free or low-cost heat sources and heat sinks.
Both systems can save energy and utility costs while increasing the resilience to external events that impact the utility infrastructure.