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Noise Control in Heating and Ventilating Systems
Published in Malcolm J. Crocker, Frederick M. Kessler, Noise and Noise Control, 2018
A. J. Price, Malcolm J. Crocker
Since vibration in the audible frequency range can easily be transformed directly into noise or propagated to some other part of the building and then radiated as noise, it is of extreme importance to control all vibration in the mechanical room to within tolerable limits. Ideally, the mechanical room should be located well away from critical areas in the building, but when this is not possible, even greater care must be taken with the control of vibration. Although it might seem that the best approach should be to furnish all pieces of equipment with vibration isolators, this is not necessarily so. The first line of attack should be to ensure that each piece of equipment is selected to produce minimum noise and is operated under its specified conditions. For example, one should choose, where possible, rotating equipment in preference to the equivalent reciprocating unit since, in general, the latter type produces much more objectionable noise. Furthermore, it is extremely important to see that each piece of equipment is balanced, both statically and dynamically, to within the recommended tolerances.
Description of Typical Building HVAC Systems and Components
Published in T. Agami Reddy, Jan F. Kreider, Peter S. Curtiss, Ari Rabl, Heating and Cooling of Buildings, 2016
T. Agami Reddy, Jan F. Kreider, Peter S. Curtiss, Ari Rabl
All-air HVAC systems for larger buildings have many more components (see Figure 11.13). A mechanical room in the basement or occupying part of a floor in taller buildings would contain one or more boilers, one or more chillers, and even several central air-handling units. The heat absorbed by the refrigerant during the cooling process must be rejected at the condenser to an environmental sink, which is usually the ambient air. This can be done directly to the air, or indirectly, first to water and then to the ambient air. The former requires an additional loop and a cooling tower as shown in Figures 11.13 and 11.14. In larger buildings, the associated system cost is still lower than that of an air-cooled condenser due to enhanced heat transfer rates from refrigerant to cooling water. Several allied equipment and components are shown, and these are discussed in Chapter 17. For smaller building loads, it is more economical to select air-cooled condensers (Figure 11.15) similar to those in a rooftop unit (Figure 11.9). Figure 11.8b is a photograph depicting the numerous air cooled condensers that occupy much of the roof space in tall apartment buildings in cities. Two water-cooled condensers can be seen in the forefront of the picture.
A data-driven model for building energy normalization to enable eco-feedback in multi-family residential buildings with smart and connected technology
Published in Journal of Building Performance Simulation, 2021
Sang woo Ham, Panagiota Karava, Ilias Bilionis, James Braun
Each residential unit has a thermostat that controls an air-source heat pump. The air handler is in the mechanical room next to the residential unit, and the heat pump is on the rooftop. There is an air vent grille in each room (i.e. a bedroom, a living room, and a kitchen). Some common spaces (e.g. hallway, a computer room, a laundry room, etc.) are conditioned by dedicated heat pumps, and they are controlled through thermostats set by the building manager. Other non-occupied common spaces (e.g. storage, loading deck) are not regularly conditioned except for emergency electric heaters. In each residential unit, a Wi-Fi-enabled smart thermostat (Ecobee3)1 and sub-circuit power metre (GreenEye Monitor)2 are installed to collect thermostat data (e.g. temperature, humidity, heat pump signals) and disaggregated electricity consumption with a 5-minute interval via web-based application programme interfaces (APIs). Weather data (e.g. outdoor air temperature and global solar radiation) is collected through a weather station installed on the rooftop (Davis Vantage Pro2).3 This study was approved by the Institutional Review Board (IRB Protocol #: 1702018811).
Real-time model for unit-level heating and cooling energy prediction in multi-family residential housing
Published in Journal of Building Performance Simulation, 2021
Sang Woo Ham, Panagiota Karava, Ilias Bilionis, James Braun
Figure 2 shows the floor plan of two adjacent units. Each unit has a dedicated air handler and a heat pump which are controlled by a thermostat. The air handler is in a mechanical room between two units, and the outdoor unit of a heat pump is on the rooftop. The return air from each unit flows without a dedicated duct into the mechanical room through the return grilles. In the mechanical room, it is mixed with return air from the adjacent unit. Some common spaces (e.g. hallway, computer room, laundry room, etc.) have thermostats controlled by the building manager, but other non-occupied spaces (e.g. storage, loading deck) are not conditioned except for emergency electric heaters.
Integrated model for comparison of one- and two-pipe ground-coupled heat pump network configurations
Published in Science and Technology for the Built Environment, 2018
Laurent Gagné-Boisvert, Michel Bernier
The selection of one of the three networks influences the interior piping length, which affects the pressure drop. The tool must then account for heat pump location to evaluate the various pipe lengths and uses the following procedure to do so. As shown in Figure 5, each numbered heat pump is located with (X,Y) coordinates which are set as parameters in the TRNSYS Type (Figure 4). By convention, the mechanical room and main circulating pump are located at coordinate (0,0). Then, the shortest length between each element (heat pump or mechanical room) is calculated.