Case Study: Performance Contracting

Loudoun County Public Schools ESPC

Loudoun County Public SchoolsAshburn, Virginia

School District Improves Ventilation With Geothermal Heat Pumps

In the fall of 2020, Loudoun County Public Schools (LCPS) initiated a study to determine what could be done to reduce the spread of COVID-19. Six schools were identified as having opportunities to improve the ventilation rates for students’ well-being. LCPS worked with CMTA, its energy partner, to develop and implement an Energy Savings Performance Contracting (ESPC) project at these schools to accomplish this goal. LCPS used the ESPC project path so they could simultaneously increase indoor air quality and decrease energy consumption.

The Challenges

  • Design an energy-efficient and cost-effective means of providing ventilation in some of the oldest buildings in the school district
  • Overcome a compressed design and construction schedule during a time when supply chains were being disrupted
  • Obtain buy-in for geothermal water source heat pumps, a first for Loudoun County Public Schools
  • Navigate approvals by the Loudoun County Historical District Review Committee and Loudoun County Permitting Office
  • Renovate 6 schools during the district's 9-week summer break
Created with Sketch.

I highly recommend the CMTA team to any entity looking for a professional partner to design and construct energy savings projects on your occupied facilities. Created with Sketch.

Edward D. Treanor V

Executive Director, Chief of Facilities, Loudoun County Public Schools

The Solutions

As a result of COVID-19, LCPS tasked CMTA with renovating six of their oldest facilities, Aldie Elementary school, Banneker Elementary School, Catoctin Elementary School, Middleburg Charter Academy, Broad Run High School and Loudoun Valley High School, to provide outside air ventilation at levels meeting current standards and modernize the buildings’ energy and envelope systems. Working closely with LCPS staff, CMTA evaluated multiple options prior to selecting the most cost-effective and energy-efficient HVAC solution for each building.

Three of the six facilities underwent complete demolition and replacement of their HVAC systems. For Aldie and Banneker Elementary Schools, the project included replacing the inefficient fuel oil-based steam boiler system and window AC units with a geothermal water source heat pump and dedicated outdoor air system (DOAS). All building exhaust streams were re-routed to the DOAS. Multiple console heat pumps replaced single radiators in spaces for resiliency and provided the ability to stage equipment, further increasing efficiency. New electrical switchgears, which replaced obsolete equipment with hard to source parts, were installed to support the new mechanical systems.

At Aldie Elementary School, the GSHP system wellfield was initially designed to be in the open field south of the building. However, after the test well in this location was permitted and drilled, the county revoked the permit, due to the wellfield being located within a flood zone. As a result, the project team worked together to redesign the wellfield in another open space north of the building. This required routing the horizontal piping under the building’s stacked stone foundation through directional boring and installing the header within the crawl space. Remarkably, all of this was accomplished within a month to allow construction completion over the summer of 2021, so the building would be ready for classes to resume.

The historic buildings needed several improvements to tighten the existing envelope and reduce energy loss due to infiltration. The project involved the addition of attic insulation where none previously existed. The crawl spaces were improved by adding a vapor barrier, sealing the existing vents, and installing mechanical ventilation that is only enabled as required.

CMTA was challenged to develop an alternative solution after the local Historic District Review Board prohibited replacing the existing single-pane wooden windows with new double-pane, low-E thermal windows. CMTA redeveloped this measure to include restoring the existing wood windows, adding new weather-stripping on all sashes, and installing the interior fixed panel tempered glass inserts to match the initial window plan’s thermal performance.

Only the original portion of Catoctin Elementary School, Broad Run High School, and Loudoun Valley High School required ventilation improvements. Given site constraints and constructability issues, substantially more efficient but traditional HVAC systems were installed. This scope of work included the installation of dedicated outside air systems, replacement of fan-coil units, and multiple replacements of rooftop units. A new fire suppression system was installed at one facility in conjunction with the new HVAC system. A new energy management system with sequences, schedules and set points that optimized the operation of the HVAC systems was installed at all six of the schools.

Additionally, all interior and exterior lighting fixtures were upgraded to LED lighting at four elementary schools. Offices and classrooms received multi-level switching and dimming capabilities. Lithium-ion battery back-up power was provided for fixtures in every classroom and means of egress. A recent roof replacement at Catoctin Elementary School made it a prime candidate for a 244-kW solar photovoltaic (PV) system to be included within the project. 

1st Place ASHRAE Technology Award - Aldie Elementary School

Throughout its almost 100-year existence, Aldie Elementary School has undergone several renovations and additions. Based on the age and construction of the building and the need to undergo local historical review for changes, a renovation project to improve ventilation might have included a like-for-like equipment replacement. However, aiming to significantly reduce the historic building’s energy use through an out-of-the-box solution, CMTA designed and illustrated how geothermal water source heat pump HVAC technology could be implemented effectively while preserving the building’s historical characteristics.

The project successfully converted the building to 100% electricity, eliminating all fossil fuel combustion and storage. It also enhanced the exterior appearance of this historic building by removing the unsightly fuel oil tank previously located at the front of the building and installing a ground loop, rather than a traditional HVAC system. This renovation project reduced the building’s energy use index (EUI) expressed in kBTU/ft2/yr from 137.4 to 40.5, a staggering 70% savings. As a result, the project transformed this 16,300 SF school from the district’s highest energy consumer per square foot to one of their most efficient schools. The facility was also awarded the coveted society level First Place ASHRAE Technology Award for its outstanding achievements. 

The Results

By utilizing the Energy Performance Contracting method, outdoor air ventilation was improved and aligned with current standards, outdated equipment was replaced, and energy efficiency was optimized. The total cost savings achieved during the first year totaled $154,668, resulting in $108,014 in excess savings beyond the guarantee. The overall project energy utilization index (EUI) was reduced from 73.7 to 39.5 kBTU/sq.ft, representing a 46% reduction. With the HVAC solutions and other energy upgrades implemented, LCPS’s goals for energy efficiency, indoor air quality, and indoor comfort were achieved. In other words, the learning environment for students and faculty was significantly improved.

This project provided an opportunity for the LCPS staff to gain experience with geothermal water source heat pump technology, which is the most efficient technology available for heating and cooling. As a result of this project’s success, CMTA is in the process of converting two additional elementary schools to GSHP systems. The upcoming projects are designed to become Zero Energy facilities, further reducing the district's carbon footprint.

Loudoun County Energy Use