The “path to ZNE” approach is a set of steps developed by PIET to address zero net energy projects for buildings and communities. This methodology was developed for projects aiming at significantly reducing the total energy consumed from the grid, with the ultimate goal of achieving energy neutrality.
The first step is to determine the energy baseline, the amount and type of energy required for the services or end uses that occupants need, such as lighting, space conditioning, hot water, etc. Only once the baseline is established, efficiency strategies can be evaluated by their relative contribution to the total energy use.
Efficiency strategies refer to building interventions that reduce the energy consumption but keep the same level of service, as opposed to conservation strategies that reduce energy by reducing the service. For the path, these efficiency strategies are grouped under envelope strategies, those related with passive measures on the building, and energy efficiency strategies, involving actions and components operating within the building.
Renewable energy, or on-site generation alternatives, would only be considered after economically viable efficiency strategies have been exhausted. This follows the premise that it is usually cheaper and easier to reduce energy use than to generate energy.
The final step of the path is to follow up on all the above activities. This means, determining the actual impact that all the implemented measures had on total energy consumption. Answering the questions: Has ZNE been achieved? How close is this building from being ZNE? Typically, this is a process that occurs throughout the project and involves the installation of a monitoring system that allows for energy data to be collected and analyzed.