Determine the energy model’s scope. In general, to simulate the performance of building systems an energy model has to include all spaces served by a common HVAC system. However, central HVAC systems often extend beyond the scope of CI projects. For example, if the project scope is a single floor fit-out in a four story building, it’s likely that the building HVAC systems will serve all four floors.
Give your energy modeler all relevant, energy-related information on the project, including glazing specifications, wall insulation, roof specifications, building uses on other floors, approximate lighting power use, site plan, and the operating schedule of base-building mechanical systems. Collecting this information will involve the owner, who can connect the energy modeler with the base-building engineer. You can use past energy bills to approximate the energy performance that needs to be input by the energy modeler.
Engage an energy modeler to review the preliminary designs and make recommendations on programming and integration with existing systems. If you still have any options relating to orientation and shading, look at those as well.
If your project is installing a Building Management System (BMS), consider scheduling or occupancy sensors that reduce air flow and setback the air-conditioning temperature in unoccupied spaces.
Consider space programming in collaboration with mechanical system zoning. You may want to link similar functions together for mechanical zoning reasons. A floor with an open-plan office space that will only be occupied in the daytime can be controlled by one zone that allows for a reasonable degree of efficiency. On the other hand, if that open-plan office floor also has enclosed conference rooms and private offices, a single zone won’t allow users to adjust temperature and airflow to the enclosed rooms when they are unoccupied, so energy will be wasted.
If they haven’t done so already, have your design engineer develop a cost estimate for the additional zoning and controls required to meet the requirements. Consider whether the benefits in terms of energy savings and improved indoor air quality of the additional controls are worth the cost of installation.
Review zoning and controls compliance. Make sure that under the proposed mechanical design each interior space with a different exposure is a separate control zone, all appropriate interior spaces have been zoned separately, and that the required demand responsive controls are included.
The majority of space uses can benefit from variable air volume (VAV) distribution. Some projects, like warehouses and data centers, may not include variable load parameters and so would not save energy with VAVs.
In typical air-conditioned spaces, 20%–30% of energy used is for delivering the conditioned air to the space through ducts and fans. The volume of air depends on the load requirement, which varies with occupancy, latent heat load, and outside weather.
