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Integrative Design Process

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The integrative design process understands that buildings, their components, their use and their place and surroundings are interrelated. Whole-building systems observe this principle by involving all stakeholders from project conception through delivery and beyond. Engaging all stakeholders in the design process to create a cross-disciplinary team and using a systems thinking approach helps to identify synergies and benefits that might otherwise go unnoticed, resulting in reduced initial and operating costs and optimizing performance. HVAC considerations include targeted energy ratings; the feasibility of natural ventilation; appropriate system sizing and controls; and indoor environmental quality goals such as thermal comfort and sufficient ventilation. HVAC performance is optimized when coordinated with other building systems, including Lighting, Water, IEQ, Solid Waste, Planted Roof and Submetering. Lighting technologies can impact the HVAC system, contributing to the building’s heat load, and HVAC systems can consume significant quantities of water. A planted roof has insulating benefits that may reduce the building’s heating and cooling loads. Collection areas for solid waste and recycling may require additional ventilation and exhaust to maintain adequate IEQ. Filtration, ventilation, temperature, and relative humidity all contribute to occupant comfort and submetering can inform water and energy efficiency measures based on usage.

The integrative design process brings key players to the table to consider and integrate HVAC with the operations and other systems of the building. Roles and responsibilities should be clearly defined and based on the common objective to balance high performance with low operating costs and achieve a high level of occupant satisfaction.

Facility Manager

The facility manager can dramatically impact the performance of HVAC systems and improve overall efficiency by measuring and monitoring energy use, evaluating thermal comfort and ventilation levels, and implementing simple automation, control and energy saving measures. The facility manager should coordinate with the mechanical engineer and operations and maintenance personnel to ensure that equipment will receive standard-sized and environmentally preferable filtration media.

Mechanical Engineer

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, which may be facilitated by energy modeling. Optimization of the HVAC system is critical in maintaining a high-quality indoor environment, including adequate levels of ventilation and filtration, which circulate air from within and outside the facility, as well as proper humidity and temperature levels during all seasons and times of day. The HVAC design benefits from the mechanical engineer’s close coordination with the architect and interior designer on appropriate thermal zones, the acoustical consultant on sound and vibration control, and the electrical engineer on the heat load of electrical systems and adequate cooling of electrical rooms. Commissioning ensures the HVAC system is installed, inspected, tested, and operated as designed.

Lighting Engineer

The lighting designer’s technology and fixture selections determine the power used by the lighting system and affect how much of this power is wasted as heat. 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 sets expectations for functionality and performance and, through their engagement and behavior, affects HVAC-related energy use and efficiency. Engaging occupants for their input on and contribution to building performance goals, including energy efficiency, and providing education about occupant control features can yield significant benefits. 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.

Interior Designer

The interior designer's placement of interior partitions and furniture affects air flow. Certain spaces, like break rooms or restrooms, can be placed next to noisy mechanical rooms to act as a sound buffer for offices and conference rooms.


The Owner’s Project Requirements (OPR) establish prioritization of critical design and operational criteria. The owner determines the project scope and budget, takes over on-going maintenance at project completion, and wants to maximize the project’s return on investment as well as the building’s market value. HVAC design and operation choices can contribute to a high-quality indoor environment and energy efficiency measures result in low operating costs and 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’s decisions - the building layout and orientation, floor-to-floor height, roof and wall materials, amount and type of window glazing, location of mechanical equipment and surface reflectance values – impact the building’s heating and cooling needs. Working with an energy modeler, the architect can provide plans and building specifications early in the design process to help predict future energy use.

Electrical Engineer

The electrical engineer is responsible for the overall design of the electrical system, including power, data, communications, security, fire protection and lighting. The electrical engineer coordinates closely with the mechanical engineer to ensure that the electrical system provides the appropriate power to HVAC equipment and controls and that the HVAC system is designed to accommodate the heat load of electrical systems and to adequately cool electrical rooms. As more building systems are electrified and as energy generation and storage systems, as well as new demand loads such as electric vehicle charging, are added at the building level, the electrical engineer’s role in ensuring the adequacy of electrical systems and developing load balancing and energy reduction strategies becomes even more critical.

Acoustical Consultant

The acoustical consultant is tasked with creating a productive acoustic environment through a combination of sound absorption technologies, blocking designs, and masking strategies. The acoustical consultant coordinates closely with the architect, interior designer and mechanical engineer to design room layouts that limit sound transfer and to identify opportunities to limit distractions, such as creating acoustical zones or providing steady background noise from HVAC equipment.

Operations and Maintenance Personnel

Operations and maintenance personnel provide important input on the operation and maintenance of HVAC equipment, including how to best optimize HVAC performance and the commissioning of the HVAC system to ensure requirements and goals are met far beyond initial installation.

Facility Manager Mechanical Engineer Lighting Engineer Occupant Interior Designer Owner Architect Electrical Engineer Acoustical Consultant Operations and Maintenance Personnel


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