November 21, 2019

Why it’s a good idea to use mechanical design-build for your school project

Dyckman

As colleges and universities jockey to attract the best and brightest students, providing an environment that emphasizes sustainability and the health and well-being of the students provides a competitive advantage.

Building trends are focused on meeting the demands of creating flexible learning spaces, improved student housing options and greater campus amenities that meet sustainability goals while still fitting within capitalization budgets. This is particularly true within the mechanical scope of work (plumbing, heating and cooling) which can account for around 20 percent of a facility’s overall budget.

Trends in higher education have created the need for a shift away from traditional construction methods and mechanical/plumbing design approaches. A movement toward design-build or progressive design-build delivery approach helps ensure the lowest total installed project costs at many of our state universities and colleges.

With these approaches, mechanical and plumbing contractors collaborate with architects, engineers and owners from the early design stage to provide value engineering through a best-value scoring system.

Through project completion, the mechanical design-build team works in partnership with the general contractor and owner toward common goals for the project. In this method, competing interests are minimized, decisions can be made faster to reduce design time and an accurate budget can be locked in much earlier, which is important in this volatile time of labor and material escalation risks.

Being involved in the early design stages of a project allows mechanical and plumbing contractors input into each space’s heating, cooling, ventilation and plumbing needs while providing live cost estimates to validate the design direction decisions. Based on occupancy and other factors in a higher education facility, a mechanical design-builder may recommend several solutions.

Chilled beams

Chilled beams have become popular for reasons of flexibility, comfort and energy use. With a chilled beam system, large “beams” or panels in the ceiling provide radiant cooling using cool water provided from a remote chiller plant. The water temperature is adjusted to stay above the room’s dew point temperature to ensure no condensation and dripping occurs. Heating can also be accomplished through a similar panel system with heating hot water.

Ventilation air is independent of temperature needs and can be controlled by the amount of CO2 detected in a space (based on the number of occupants and their activity level) and can be provided through the chilled beams themselves. In fact, buildings in higher education that have high ventilation air needs pair well with active chilled beams that require very high primary airflows.

Compared with a traditional ducted system with ceiling diffusers, this provides a more comfortable space with uniform temperatures across the room volume. Benefits include fewer drafty or stagnant areas that are a distraction to learning, flexibility to accommodate changes in seating arrangements and a much quieter system that enhances the learning environment. A lowered operating cost can also result and help offset capital costs in the long run.

VRF systems

VRF systems have also become very popular because of low installation costs and reliable comfort. This is a refrigeration-based system, so it could be popular for facilities without central mechanical equipment plants (which are needed for chilled beams).

This system relies purely on airflow to distribute the heating and cooling, though, so care needs to be taken in the design to avoid objectionable mechanical noise and stagnant or drafty areas. The system requires more periodic maintenance directly within the learning environment, which could be inconvenient if service is needed during the occupied times of the day. Redundancy is also not as convenient to implement as in the chilled beam system.

VRF systems also employ a separate decoupled ventilation system affording similar benefits to the chilled beams design. The smaller fan systems result in improved energy savings over larger central type systems and are comparable to chilled beams in overall energy performance. The biggest advantage of VRF systems in higher education facilities without central plants is a much lower installed cost than most all other systems.

VRF systems can also deliver air through floor or low-wall grilles in a “displacement” approach, which is a popular option for large spaces such as lecture halls. This approach allows for excellent temperature control and air quality in the occupied volume of the room, quiet air distribution and a draft-free environment.

Gender-neutral bathrooms

On the “wet side” of mechanical considerations, a trend in modern public higher education facilities is gender-neutral restrooms. These can create a challenge with respect to plumbing and exhaust, since there are many more enclosed stalls (much like the European WC model).

An economical way to accommodate floor drains is to slightly slope each room out to a common area with minimal floor drains, versus a dedicated floor drain for every stall.

Exhaust can present challenges as well. A single exhaust fan for all stalls is economical for first cost, whereas using occupant sensing at each stall and only exhausting ones that are in use could save energy but only over a very long timespan. Undercutting each door slightly can allow for make-up air while simultaneously accommodating water from a plugged toilet to flow out of the stall.

In general, recognizing popular higher education trends and involving a mechanical design-builder early in the project design stage along with the general contractors and design teams in a design-build or progressive design-build delivery approach will greatly enhance the learning environment, minimize operating costs, and maximize the overall value delivered to owners.

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