Effectively merging new additions while bringing the existing structure up to current building codes is a major challenge of working with an older building. Another challenge is adding or updating an hvac system which was not a part of the original structure.

The architects turned to McDermott Group of Sacramento for consultation on updating the hvac systems for the new district attorney’s offices. The client had several pages of hvac design criteria which had to be met, including design conditions, load criteria, zone sizes and zone controls.

The existing hvac systems in the building were outdated and would not be able to handle these new heating and cooling loads.

In the past, engineers at McDermott Group would have generally approached a project like this by manual take-off of the different areas and building assemblies and entering them into an hvac load analysis program.

This would have to be done for each room or zone, depending on how detailed they wanted their analysis to be. They would then sketch out the zoning and duct layout onto a copy of the building plan and finally draw the final layout using a CAD program.

This is a time-consuming and inflexible process. Moreover, if the client did not like the initial design, they would have to duplicate a large portion of the load/zone analysis, re-sketch the new layout and re-input it into the CAD system. Mike McDermott, owner of McDermott Group, knew there had to be a better way.

Found on the Internet

One night in late 1997, while surfing the Internet for programs that could expedite the company’s hvac design process, McDermott found a program called MeMate HVAC by Energy & Mechanical Systems Consultants, Inc., of Santa Monica, Calif.

This program claimed to be able to run detailed heating and cooling load analysis, as well as layout ducting and zoning inside of AutoCAD.

“I downloaded the demo file with an interactive tutorial and was able to appreciate results within the first two hours,” McDermott said. “By using this new software technology with my current version of AutoCAD, I was able to run my loads, lay out my ductwork and select my equipment all within one program.

“What made it even better, was that the artificial intelligence built into the software automatically selected diffusers, grilles, duct fittings and sizes with the click of a button. Or, at any time, I could override the automatic input and select my own devices and/or sizes.”

MeMate’s object-oriented approach allows engineers to experiment with various layouts quickly. The end product is a detailed, double-line duct layout with all duct runs and devices labeled. In addition, the software can generate a bill of materials of the hvac design for the contractors.

After obtaining a commercial version of the MeMate program, McDermott Group put it to work on the Yolo County district attorney’s office project. Once they had the detailed room-by-room heating and cooling load analysis, they started putting together zones based on the client’s design criteria.

With more than 20,000 sq ft of office space distributed over three floors, less than two feet of space above the ceiling for light fixtures, duct runs and fire sprinklers, and one central duct shaft for all plenum drops from the third-floor roof, the engineers found themselves with a real distribution and control challenge.

“The general contractor and mechanical contractor had been selected early in the design process,” said McDermott. “Working closely together we all agreed that by using six package rooftop units with VVT zoning and the direct digital controls specified by the district attorney’s office, the zoning and budgetary criteria could be met.

“We started laying out zoning scenarios for the review of the contractors and client using AutoCAD with MeMate. The speed and simplicity with which we were able to evaluate various designs enabled instant decision-making on which approach would be the most workable and cost effective for the building.”

Once the zoning was decided upon, the greatest hurdle for the engineers was finding a way to get the supply and return air plenums from four of the rooftop units down a single duct shaft to the first and second floors. This had to be accomplished while providing the required VVT crossovers for each unit and fire-smoke dampers out of the plenum.

It took several design iterations to get a viable solution, but by using MeMate, they were now able to evaluate a variety of options quickly and make the best decision.

The construction work is currently underway and moving along quickly on the Yolo County district attorney’s new office building.

McDermott Group also continues to use MeMate on a variety of projects.

MeMate HVAC is available for review from the MeMate website at www.memate.com.