A Brief Multiple Choice Test
Facility Condition Assessment and the ChallengeThe Eliot-Pearson School is part of Tufts' Department of Child Development and has been in existence nearly 80 years. The school was founded as a nursery school and eventually evolved into a nursery training school. Its affiliation with Tufts University began in 1954 and was absorbed into the university's Medford campus in 1964. Eliot Pearson Children's School is unique in its integration of child development research and theory with effective practice.
The school offers preschool, kindergarten, and first and second grade programs. The facility provides student teachers with opportunity to observe and assist in the classroom and childhood early development projects.
Today, this department occupies 22,500 sq ft of building with four wings to accommodate faculty, staff, and students; offices; classrooms; the Evelyn G. Pitcher Curriculum Resource Laboratory; and the Eliot-Pearson Children's School.
The first building was originally constructed with a gas-fired boiler and a forced hot water heating system. In the 1970s, an electric heat building was constructed, more than doubling the size of the school. With ongoing success, the university planned for two more additions during the summer of 2001, while proceeding forward with the building's deferred maintenance plan.
Leading up to this deferred maintenance program, the university had years earlier placed a high priority on facility condition assessment and its associated facility condition index (FCI) with Richard Goulet, the university's director of facility management and construction, championing the investment throughout the three campuses.
Goulet had made it an O&M goal to reduce the FCI benchmarking process down into an area of "controlled" facility management care. Reinvesting in the university infrastructure this way with a plan for repair, replacement, and/or renovations is always a struggle as department budgets and priorities change year to year and even month to month.
At Tufts University, this successful plan had the commitment from the top-down to implement facility condition assessments and improvements over a 10-year master plan. The FCI benchmark had proven to be a viable tool used by Tufts in evaluating the condition of the building assets from the outside of the building to the mechanical and electrical infrastructure of each campus facility.
The index scale rating system provided a simple, but effective, means to demonstrate to the university the condition and useful life of equipment, systems, and buildings. The rating system scores the condition of facilities to assist in determining the priority for repair or replacement. The index allows owners to strategically plan for repair or replacement as well as contribute to the school's building master plan program.
Window of OpportunityThe growing success of the nursery school had required Tufts to increase the school program to an 11-month operation, thus reducing the window of opportunity to just four weeks of in-classroom repair and replacement time. At the same time, the building's problems had grown from deferred maintenance to include space comfort problems with the increase in utilization of the occupied space.
Initially, because of the FCI inventory of current conditions, forecasted repair, and replacement costs, Tufts recognized that the time had come to replace the antiquated hvac systems at the Eliot-Pearson building.
This conclusion was further reinforced by the decision to act based on recent space comfort problems that aggravated the already deficient equipment. While visual inspections, historical workorder records, and estimated useful service life all contribute to a comprehensive deferred maintenance master plan, it does not replace the human condition or climate controls issues that are not always easily identified.
In the past, the university had procured energy, commissioning, and design services from Sebesta Blomberg & McKew (now Sebesta Blomberg New England), the Northeast regional office for Sebesta Blomberg, MN. Knowing the professional service relationship between Tufts and the firm, L/K&R approached the engineering management firm to partner in this engineering-construction venture due to the problems associated with this particular building and the time available to resolve these problems.
The clock was ticking, and repair and replacement criteria had now taken on a need to address the current occupant complaints, as well as assess the impact of two planned building additions, the antiquated 1964 heating system, and the existing electric heat portion of the building.
To complete this work, Sebesta Blomberg presented two options with the first titled "like-for-like" changeout and the second option being a more comprehensive solution to all the building issues.
Taking full advantage of the limited window of opportunity, the process of choice was D-B, beginning with a system analysis and selection matrix process (Table 1). Integral to this project was the careful preplanning and equipment prepurchased in order to deliver the project in a timely manner.
At the Eliot-Pearson School, the problematic hvac system was summed up as follows:
- Equipment with automatic temperature control components that didn't work;
- Equipment on the premises that was more than thirty-seven years old (1964);
- Equipment noise from packaged, air-cooled, air conditioning equipment located in classroom ceiling space;
- Inadequate space zone control and/or outdoor air ventilation;
- Original low-boy unit ventilators that discharged supply air in the children's faces;
- Blocked supply air grilles on unit ventilators due to classroom material being stored on the floor-mounted equipment; and
- Air conditioning that provided limited space comfort due in part to limited airflow at the furthest points of the supply air ductwork.
Innovative Solutions: 'Thinking Outside The Box'With small children comes the potential for big problems. At the Eliot-Pearson facility, the traditional, floor-mounted classroom unit ventilators posed a special problem for teachers because of its relatively sharp edges and grille work were near where little fingers could reach them.
Since the late 1950s and early 1960s, design engineers specified the traditional school classroom ventilator with hvac capabilities. While this equipment has been the cornerstone of schoolhouse hvac design, the D-B team chose a more creative solution because of teacher concern for pupils.
As in many 1970s vintage schools, classrooms were fitted with unit ventilators with hot water coils and DX air conditioners. The life spans of these unit ventilators were typically 15 to 20 years. The 1970s vintage unit ventilators at the Eliot Pearson School were no longer functional and were disconnected.
The school's classrooms were retrofitted with ceiling-mounted package air conditioning units with exposed supply air ducts to provide air conditioning. The fintube radiation and controls were left in place to provide heating. These units, however, did not have outdoor air intakes, and cabinets were installed along the exterior walls covering the baseboard radiators. The retrofit left the classrooms with cold drafts in winter and stale air in the summer. Sebesta Blomberg was approached to provide some recommendations to address the climate conditions in the school.
What school officials were looking for was a quick and economical solution to provide comfortable hvac. School officials requested that the new system to be able to meet the guidelines for ventilation requirements as described in ASHRAE Standard 62. Several options were investigated.
Using the analytical methods of the ASHRAE System and Equipment Handbook, Chapter 1, the design engineer applied the system selection matrix found in Table 1, to focus on the optimum hvac solution for this project, recognizing the unique concerns of the university and the timeline required to finish the project.
Option 1 was to replace the unit ventilators with new units. The problem with this option was that it offered preschool children the opportunity to place objects, crayons, food, juice, as well as fingers, into the slots on the unit ventilator.
A more comprehensive solution (Option 2) was to replace the packaged a/c units with gas-fired furnaces equipped with a DX coil and remote-mounted condensing unit. This option could provide individual room climate controls and, with outdoor air intakes, could meet the ventilation requirements.
This option was also the most economical because the existing ductwork could be reused and the power consumption reduced. However, furnaces available in these small sizes were single stage and required the furnace to cycle on and off, providing intermittent ventilation.
Option 3 was to replace the packaged a/c unit with a fancoil unit equipped with a hot water heating (hydro air) coil, DX coil, and remote-mounted condensing unit. The fancoil unit's fan could operate continuously while maintaining constant supply air temperature.
This option called for the supply air temperature from the fancoil unit to be controlled using a Johnson Controls unitary controller with air temperature sensor located in the supply duct and modulating heating valve. The forced hydro air system provided safe and economical climate control.
The concern with this option was, with the existing supply air diffusers located down the center of the room and the large exterior glass walls, the hydro air system would feel drafty. The cold window would absorb heat radiating from the students' bodies and give the sensation of a cold draft.
To address this comfort issue, Sebesta Blomberg recommended installing hot water radiant panels at the ceiling, along the exterior walls of the classrooms (Option 4). The radiant panels would provide some radiant heat and warm the surrounding surfaces. Sebesta Blomberg recommended using 2-ft-wide Runtal radiant panels, which are designed to deliver 660 Btuh/lin ft at a design water temperature of 180 degrees F.
Constant airflow from the fancoil units helped reduce stratification and temperature drifts. The control strategy was set up so the radiant heating panel provided primary (one stage) heating for the classrooms and the fancoils provided morning, warm, tempered air for first stage heating and second stage heating (with reset water temperatures) if required while in the occupied mode. In the unoccupied mode, the radiant panels would maintain room setpoint temperature and the fancoil units would cycle on.
The other option considered (Option 5,) was to install radiant floor heating in lieu of the radiant panels, but it was not pursued due to high capital costs and time constraints.
A Plan Is SubmittedSebesta Blomberg recommended Option 4 as the best overall solution. School officials agreed and preliminary plans were drawn up. Based on the preliminary design, an RFP was developed. Prequalified mechanical contractors submitted a guaranteed maximum price. L/K&R accepted Grinnell Mechanical's (Burlington, MA) proposal to install the mechanical systems.
The existing drafty unit ventilators as well as the fintube radiators behind the cabinets were removed. Carpenters removed the grilles (for the fintube) along the walls and new cabinet counter tops (flush with the wall) were installed. This eliminated the chance that objects could be dropped behind the cabinets.
Hot water (heating) piping to the faculty offices' fintube radiators was changed from a series arrangement with one thermostat and control valve to a parallel configuration with self-contained thermostatic control valves in each office.
The decision was made to replace existing natural gas-fired boilers with new, energy-efficient boilers with hot water reset controls provided by Viessmann (Warwick, RI). Viessmann's Dekamatik ddc system, which can be tied into a bms, was also selected.
Given the tight schedule, the work was prioritized. The AHUs and radiant panels were given the highest priority in order to release the classrooms and faculty offices. The air conditioning side was completed in several weeks. The DX condenser cooling fans were fitted with custom-built screens to prevent accidents. The boiler installation was completed last. Each system was commissioned as soon as the startup checklist (provided by Sebesta Blomberg) was completed by each of the trade's foremen.
The benefits of this application were instantaneous. Ceiling-mounted radiant heat panels eliminated the floor-mounted fintube radiation and classroom ventilators. The old equipment was not operating properly for adequate space comfort and ventilation. In addition, these units created two issues of concern. The first issue was that obstructions, such as toys and books, were being placed over the equipment supply air outlets. The second concern was the fact that the supply air blew in the faces of the students because the units were so low to the floor.
To fix these problems, the new hot water radiant panels overhead and next to the windows will provide more evenly distributed heating, covering the cold perimeter in the winter as will the new central AHUs. The supply air distribution from these units are above the occupants, and will provide unobstructed ventilation, as well as supplemental heat and summer cooling.
The fancoil units (hung above the ceiling) replaced the packaged air conditioning units for cooling and heating and will provide outdoor air ventilation. This eliminated the air cooled condensers and their noisy refrigerant compressors from within the building to outdoors. The new central air handlers are inherently quieter, provide more ventilation, and are more energy efficient than the equipment being removed.
The old hot water boiler (rated approximately at 70% efficient), which served only half of the building, has been replaced with a new boiler with outdoor air reset controls and flue damper (at approximately 84% efficiency) that will provide improved performance and eventually serve the entire facility, displacing the electric heat in the faculty area.
In addition, the hot water pumps are sized to provide lead lag performance. In this manner the hot water system has the inherent capability of having a standby pump while minimizing the electrical energy of total motor horsepower (i.e., one pump operating).
New ddc systems have replaced the existing standalone controls. The new control system includes a simple, but comprehensive, ddc system on the boiler and controllers for the fancoil units. The ddc systems have the capability to interface with the campus-wide Johnson Controls bas in the future.
And, finally, new, self-contained heating valves will provide individual control in each of the faculty offices.
The second phase will include replacing the electric baseboard heating in the faculty offices with forced hot water baseboard. The first phase of work has been to address the chronic space comfort problems experienced in the classrooms.
In addition, we stepped back and took a "big picture" assessment of the entire hvac installation that also included a review of the new and future building additions. The new boiler was sized to serve the classrooms, the two new additions, and faculty offices (electric heat space).
The final action item of the project was to assemble all the documents on the new equipment and design of the various systems into a project book. The project book includes O&M guidelines, installation instructions, equipment warranties, design intent documents, plans and specifications, meeting minutes, control sequences, and flow diagrams of each system. This project book can now be used to assist the owner in training new maintenance staff and for reference in future renovations to the school. ES
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