Top 10 “Must-haves” in HVAC Design
In the post-COVID construction environment, accelerated project design schedules are becoming the norm. Pressure to meet budget and timing deadlines is heavier than ever before. As an experienced HVAC designer and a MEP project manager, there is temptation (and even push from some arenas) to eliminate some portions of the design process to meet this new normal. However, there are several areas of HVAC design that require careful and thoughtful consideration or there will be major issues. Here is my Top 10 list of “must-have” Items in HVAC design:
HVAC Load Calculations
Over-sizing or under-sizing HVAC equipment can lead to inefficient energy consumption, inability to control humidity and/or temperature, and occupant discomfort. Proper load calculations are essential to determine the proper size of HVAC equipment. This is elementary, but in the age of truncated design schedules it is tempting to use simple rules-of-thumb or past projects to determine HVAC loads. This is a mistake and very risky.
Internal Heat Gains
Internal heat gains from occupants, equipment, and lighting can significantly affect cooling loads. Accurately estimating these gains is necessary to insure proper system sizing and performance. This requires obtaining information regarding these items from building owners early in the design process. Building owners and architects are more concerned about the site plan, the floor plan, and the programming requirements during these early stages of design, and in the late stages of the design process everyone is just trying to finish their documents. This can mean that internal heat gains are forgotten until the building is built and there are issues controlling temperature or humidity in the building.
Ductwork Design
It is my opinion that not enough time is being put in these days to consider duct sizing and layout. The result is airflow issues, increased energy consumption, air noise, and system imbalances. Ductwork design must be carefully and meticulously considered and coordinated so that air can be distributed properly and so that ductwork is not installed in undesirable locations. Ductwork is like a major league umpire; it should never be noticed. If it is an eyesore, if the air noise is a nuisance, or if the air distributed from the duct is not properly conditioning the space, it will be noticed, and that is not good.
Zoning
Inadequate zoning control for the different areas in a building will result in uneven heating and cooling, higher energy consumption, and occupant discomfort. Targeted temperature control in different areas, or zoning, is critical to the function of any building and requires a clear understanding of the needs and requirements of the building users. Implementing proper zoning in HVAC design requires time to discuss, consider, and coordinate. Skipping this step may not result in the HVAC systems not working properly, but you can be assured that it will result in a large portion of the building users being unsatisfied with the HVAC systems in the building and therefore unsatisfied with the building.
Thermostat Locations
Placing thermostats in areas with fluctuating temperatures such as near windows, near equipment that produces intermittent heat, or in direct sunlight will lead to inaccurate temperature readings and occupant discomfort. Thermostats should be thoughtfully located in areas representative of the average conditions for that zone. With little time, it is enticing to speed through this simple and easy part of the design process, but if care is not taken it will most assuredly result in occupant discomfort.
Maintenance Accessibility
Designing systems without considering accessibility for maintenance and repairs can lead to increased downtime and higher maintenance costs. Adequate space should be provided for accessing and servicing equipment. With tighter construction budgets and less design time to coordinate with architects, it has become a lost art to “fight” for this space. But put yourself in the shoes of the building owner and ask, “Could I easily service and maintain this equipment in the space that I am providing?” Then fight for the space. The building owner will thank you, and in turn so will the architect.
Noise
HVAC systems can generate a lot of noise. Failing to consider noise issues during the design process can result in major problems. Simple solutions for noise like locating HVAC equipment away from sound-sensitive areas, ductwork sizing, air device selection, and return air paths can make a huge difference in mitigating these issues. And where more robust sound control is needed, solutions like chiller noise control, internal ductwork acoustical insulation, sound attenuators, or vibration isolators should be implemented in the design process where appropriate to address sound issues before they happen.
Building Design and Aesthetics
HVAC systems should be integrated with the overall building design and operations. What the architect and building owner are trying to achieve cannot be ignored by the MEP engineer. Coordination with the architect and other engineering consultants is essential. 3D-design software is a great tool to analyze all building components and fully accomplish the design intent for the building. Disregarding the architectural and structural aspects of a building leads to conflicts, inefficiencies, and poor aesthetics.
MEP Systems
HVAC is only one of the systems designed by the MEP engineer. Electrical, plumbing, fire protection, and sometimes technology systems are also designed by the MEP. All these systems must work in harmony, and poor coordination can lead to conflicts, inefficiencies, safety issues, and additional construction costs. Early and continuous collaboration with other MEPT disciplines is essential for HVAC design. Working ahead, a good QA/QC process and constant and clear communication are a must for any MEP engineer who is pursuing excellence for their firm, for their client, and for the building owners they serve.
Cohesive Drawings and Specifications
Drawings and specifications align with each other as well as with owner design standards, latest adopted codes, and best industry practices. Specifications are sometimes seen as an afterthought, as something you do in a few hours at the end of the design process right before the project deadline. This leads to discrepancies between drawings and specifications in HVAC design, which results in significant issues during construction such as construction delays, increased costs, and poor system performance, to name just a few.
If you enjoyed this Top 10 list from LTY, look for more in a monthly series as we look forward to our 10th Anniversary in October 2024. Next up: Top 10 Things I Learned in My Internship.
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