The ground source heat pump (GSHP) and variable refrigerant flow (VRF) systems are the most competitive HVAC technologies in the current market. However, there are very few studies reporting the comparison of the annual energy consumptions and Electric Peak demand reductions between GSHP and VRF systems because of the limitation of the whole building energy simulation software. Current version of EnergyPlus can model both GSHP and air-source VRF. Therefore, three representative US climate zones including Chicago, Baltimore and Atlanta are selected for conducting this comparison study. The EnergyPlus simulation results show that the GSHP system not only saves more energy than the air-source VRF system but also significantly reduces the Electric Peak demand regardless the climate conditions. This makes the GSHP system a more desirable energy effi cient HVAC technology for the utility companies and their clients.
How to Achieve LEED Points by Installing VRF HVAC Systems
A state-of-the-art HVAC technology, Variable Refrigerant Flow (VRF) zoning systems are poised for dramatic growth in all areas of commercial construction because they provide precise zoned control that can contribute points toward LEED® certifications. This paper describes the major benefits of VRF systems and how to garner LEED points by applying these systems. But first, a quick review of this cutting-edge technology. VRF zoning is a method of providing precise comfort control to buildings with multiple floors and areas by moving refrigerant to the zone to be heated or cooled. The systems, which can simultaneously cool some zones while heating others, have many benefits.
Micro Thermo Technologies Transcritical CO2
Awareness of climate change has altered the landscape of modern refrigeration. A focus on greenhouse gases (GHG), the carbon “footprint” of organizations and regulatory limits on HFCs has encouraged many organizations to look for alternative ways of providing refrigeration. One way in which companies lower their contribution to GHGs is using alternate refrigerants - like Carbon Dioxide (CO2) - that have significantly reduced impact on the environment. Micro Thermo Technologies recently worked with a large customer to manage the first supermarket transcritical CO2 refrigeration system in the U.S.
Mixing Air to Maximize Savings
Good blending of outside air (OA) and return air (RA) streams is crucial to minimizing annual AHU energy consumption and providing good winter freeze protection for coils. Many designers assume that the section of the AHU commonly called the ‘mixing box’ will provide the effective and necessary air blending… an assumption which often leads to irritating and expensive operational results. In central station AHU’s, when OA and RA streams meet in the “mixing box” (a true misnomer), the intent is that the new Mixed Air has a consistent temperature and moisture characteristic at all points in a given downstream face area. Unfortunately, the widely adopted “best practice” of positioning the OA and RA dampers to flow towards each other does a terrible job of mixing the air.
Pressure Control for Today's High Performance Green Buildings
The control of building pressure is essential to maintain acceptable indoor air quality (IAQ), thermal comfort and structural integrity. Negatively pressurized buildings result in the transport of untreated outdoor air into the building. This untreated air will result in:
- the transport of dirt, dust and other contaminants
- the transport of moisture in humid climates (climates where the outside dew point exceeds 60 degrees F)
- humidity control issues that result from the transport of untreated moisture
- mold growth in and near the buildng envelope that result when the outdoor air temperature varies significantly from the indoor air temperature
Variable Capacity Compressors and Variable Speed Fans Save Energy and Save Money
Many applications can benefit from HVAC equipment with variable capacity scroll compressors and variable speed supply fans that reduce operating costs. With the 180,000 square foot department store in Naples, Florida, Dillard’s sought the expertise of AAON in order to accomplish significant energy savings and still provide many years of unit operation in a highly corrosive coastal environment. This paper lays out the issues faced by the Dillard’s department store in Naples and how the AAON equipment with variable capacity compressors, variable speed fans, and e-coated coils was able to solve them.
Ventilation of Commercial Dishwashing Machines
Proper ventilation of cooking appliances and dishwashers in commercial kitchens is critical to correct operation, controlling operational costs and ensuring comfort conditions for the staff. The heat and humidity from dishwashers, and associated sensible and latent heat load to the space, is significant. The heated water vapor from dishwashers, if not properly ventilated, escapes into the room adding a significant latent heat load to the space, causing discomfort and adding considerable cooling load to the building HVAC system.