Quality Ideas

Cost Effective and Energy Efficient Systems

The majority of our work has been design/build and service since our company was originallly founded over 50 years ago. Energy efficiency has played a significant role in HVAC design for quite some time. With the recent advent of LEED® and the push toward "green building" design, energy efficiency has become a primary objective in HVAC systems design and operation.

Since heating, ventilation and air conditioning account for approximately 50% of the overall electrical load of a building, there is a great deal of cost savings opportunity. Jarrell has been using the Trane Trace energy modeling system for years to determine energy costs.

Renewable Energy has become a hot topic in the construction industry due to rising energy consumption and environmental issues. Sources of renewable energy that are related to the mechanical systems consist mainly of geothermal (ground), wind generation, solar, and cogeneration. Research into these systems is basically in the infancy stages; however, the government has established tax incentives for using these renewable energy systems. Some utility companies are also offering incentives and rebates in an effort to minimize their capital expenditures required to produce additional energy. We are looking at an exciting time in our industry, while new energy efficient approaches are being perfected.

To date, the majority of our renewable energy work has been on geothermal and solar source systems.

We have worked on a number of the Corps of Engineers projects which have included some element of renewable energy systems.

A geothermal system heat pump system utilizes the earth as a heat source (in the winter) or heat sync (in the summer). This system takes advantage of the moderate temperatures in the ground as compared to the actual outside air temperature. The ground loop takes the place of the cooling tower and boiler that are typically required in a conventional water source heat pump system. During the summer months, the heat from the building or space is rejected back to the ground. In the winter, heat from the ground is transferred back to the building or space.

We are in the process of completing a geothermal ground source heat pump project at Linn State Technical College in Linn, MO. Our scope consists of the heating/cooling of a 74,000 square foot automotive school addition. This project has 176 tons of installed cooling capacity and 57 heat pump systems.

Another system that we are working on is the Variable Refrigerant Flow/Volume (VRF/VRV) system. In a VRF system, multiple indoor units, or evaporator coils, are connected to a single outdoor unit, or condensing unit. Each condensing unit contains multiple compressors, at least one of which is equipped with an inverter. The inverter varies the speed of the compressor, the amount of refrigerant being circulated in the system, and thus consuming less energy at part-load conditions. The VRF system allows the use of multiple evaporators of differing capacities, can provide multiple thermally controlled zones while minimizing the number of condensing units, can allow simultaneous heating and cooling for the different zones, and can recover heat from one zone to another.

There have been attractive claims made as to the energy efficiency of VRF systems, however at present time there is not an ARI (American Refrigeration Institute) or other third party rating system in existence for measuring the efficiency of the system. There is an ASHRAE study in progress at this point; the system has been installed at the ASHRAE headquarters in Atlanta, Georgia in order to better evaluate and quantify the actual performance of a VRF system. A committee has been established to have a study and rating system by 2012. We are watching these studies very closely and are currently installing our first VRF system at the Garden Plaza project. This Skilled Nursing Facility is a 64,000 square foot new construction project. It has 120 patient beds, with 84 patient rooms. All patient rooms will be served by PTAC units with the common areas; which include business administration, living rooms, conference rooms, work room, bookkeeping, medicine, kitchen and nourishment room served by the VRF system.

We do see considerable potential for energy and cost savings with the system, and there have been claims of 30% HVAC savings over a chiller system.

For more information, please contact Michael C. Jarrell or Derek Kenkel