Integrative Design Process
The integrative design process understands that buildings, their components, and their context are interrelated. Whole-building systems observe this principle by involving all stakeholders from project conception through delivery and beyond. Including all stakeholders allows for the identification of synergies that otherwise would go unnoticed, and as a result, reduces initial and operating costs, and reduces energy consumption while providing conditions to promote health and comfort. The mutually agreed-upon Owner’s Project Requirement (OPR) for HVAC could include targeted energy ratings; climate impacts on natural ventilation and mechanical system sizing; and indoor environmental quality aspirations such as thermal comfort for occupants and sufficient ventilation for indoor air quality.
Example requirements include a 15% reduction in total building consumption or a 50% improvement in occupant thermal comfort through implementation of an occupant survey. An HVAC-specific integrative team could involve the mechanical engineer, lighting engineer, architect, interior designer, facilities manager, maintenance department occupant and owner as representative of the broader whole-building picture.
The facility manager collaborates with the building owner to reduce operating costs and works with the occupant to provide a comfortable space. The facility manager should inform the mechanical engineer about maintenance challenges before the design is completed so that the system has adequate access to equipment. Consumables, such as filtration media, pose a real expense. The facilities manager should work with engineers to see that equipment will receive standard-sized and sustainably manufactured materials.
The mechanical engineer is responsible for sizing the heating and cooling equipment based on both internal heat loads and heat loss through the building envelope. The mechanical engineer works with other disciplines to ensure that both HVAC needs are met and that system choices allow for ease of maintenance.
The lighting engineer ultimately determines the power used by the lighting system. The engineer’s equipment selection also affects how much of this power is wasted as heat. Electrical rooms may also require increased cooling as lighting power increases. Daylighting systems can save on lighting energy costs, but the HVAC impact of larger windows should be considered as well to optimize overall savings.
The occupant has a great impact on HVAC-related energy use. Individual controls help ensure comfort for those in the building. Occupants without thermal controls often resort to inefficient (and often unsafe) practices like operating space heaters under desks. Where individual controls are not practical, ensure an easy method of communication between occupants and the facility manager for adjustments to temperature and humidity settings.
The interior designer has an impact on HVAC systems in several ways. Interior partitions and furniture placement affect air flows. Certain space functions, like kitchens or restrooms, can be placed next to noisy mechanical rooms to act as a sound buffer for offices and conference rooms.
The owner must be on board with HVAC design and operation choices, as these will have an impact on first costs. Lower operating costs, however, result in greater operating income. That increase in income also increases the value of the building as an investment , as the worth of a building is often determined by the net present value of future cash flows.
The architect has as much or more impact on the HVAC system than any other member of the integrative team. An architect’s decisions - the building layout and orientation, roof and wall materials, amount and type of window glazing, and surface reflectance values – decide the building’s heating and cooling needs. The architect, in collaboration with the integrative team, should determine the project goals at project conception. Working with an energy modeler, the architect can provide drawings and building specifications early in the design process to help predict the future energy use of several alternatives. The building layout, floor-to-floor height, and position of mechanical rooms affect HVAC efficiency as well.