Data Driven Design For Hospital HVAC Systems: Designing to Optimize and Maximize Value

An important aspect of Newcomb & Boyd’s engineering is “Data Driven Design.” This is incontrast with other potential approaches where some designers may say, “well this is how we always do it” or asking the Owner, “tell us what you want.” Instead, with this approach, we act as an expert consultant advisor collaborating with the Owner, the Architect and frequently the Construction team, to identify and evaluate options to make informed decisions about what the best long-term approach for the specific project is.

Initial System Selection

This is most valuable when it comes to initial system selection. Sometimes the best approach is obvious, but often, there are a range of options that could work.

For example, depending on the size, possible HVAC systems for a significant Medical Office Building could be Packaged DX roof top units, air-cooled chillers, or a water-cooled chilled water plant.

First Steps: Listening, Capital Cost, and Operating Cost

The first step we take is to listen to the Owner, hear their concerns, present some possibilities, and understand what they are open to exploring or not. We then develop those possible options sufficiently so that a conceptual cost estimate can be developed for each.

Energy modeling occurs simultaneously to understand the cost of operating the system over the life of the building. A system that costs more initially but is more efficient may pay back that premium over a short time.

Other Important Considerations

While first cost and energy costs are primary considerations, there are many other things that go into the comparison and analysis that can drive the ultimate selections. The system expected life, maintenance cost, carbon and sustainability, acoustics, space requirements, lead times for procurement, complexity, and critically, owner maintenance, staff familiarity, and comfort with the proposed system, all can matter very much and may drive the decision.

With all this data gathered and compiled into a matrix, we and the project team can easily compare and jointly choose what is best for this specific project. This is Data Driven Design.

Examples of Data Driven Design

1. All Air versus Chilled Beam System for new Winship Cancer Center Tower at Emory University Hospital Midtown

An example of this occurred at Winship Emory Midtown. Early in the design of this 19 story, 465,000 square foot inpatient and outpatient dedicated cancer treatment facility, we evaluated two distinctive HVAC system for the 19-level tower above the diagnostic treatment podium consisting of alternating outpatient and inpatient floors

A traditional all-air system was compared to a chilled beam system with Dedicated Outdoor Air Systems (DOAS). Capital cost, energy use, maintenance, comfort, and operating cost were all compared. While for many MEP system comparisons, there could be other implications on the architecture or site, for this comparison there were significant architectural implications. The chilled beam system with a DOAS requires significantly less overall mechanical equipment space since we are moving only a third of the air of an all-air system. With the chilled beam system, duct distribution is also much smaller, which permits a smaller ceiling plenum depth and the ability to reduce the floor-to-floor height and thus the overall height of the building.

For this project that reduction was 8” per floor. This reduces the required material across the building construction including foundations, columns, risers, and most obviously exterior façade. All of these non-HVAC impacts and cost savings are part of the cost data comparison of the two HVAC systems.

2. Build New Chilled Water Plant or Expand the Existing One?

At the same facility, around the same time the building air system was being evaluated and the chilled beam system was selected, another detailed analysis occurred comparing the cooling and heating infrastructure.

Early design included a new dedicated chiller plant and hot water heating plant in the new facility with steam for humidification and sterile processing from the existing main hospital across the street; however, to align the project scope with budget and maximize program space, an alternate design to expand the existing chilled water plant and use the steam plant in the main hospital to serve the Cancer Center and was developed and compared to the dedicated plant base option.

In addition to base analysis for the two options for the capital, energy and maintenance costs, a detailed analysis of existing chilled water and steam plants and facilities including loads, redundancy, and expansion options was part of the data.

Ultimately expanding and connecting the existing systems was selected and saved more than $4 million in mechanical and electrical capital cost, significant additional savings were part of this decision. By deleting the new central heating and cooling plants, additional space in the building became available for other uses. Coupled with the chilled beam system selection, which reduced equipment size, the team was able to delete a full planned mechanical floor by relocating equipment and adding a small mechanical penthouse on the roof of the podium to serve the operating rooms more economically.

This provided significant savings beyond the direct savings for the mechanical and electrical systems providing more value for Emory Healthcare.

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