Heating Canadian homes is an energy intensive endeavour. Factors such as the northerly climate and dispersed population cannot be avoided but inefficiencies with heating system design can. The mismatch between the grade of heat required to heat a home and that produced by conventional heat sources results in large amounts of wasted energy and exergy. Low–grade heating sources, such as ground source heat pumps, when combined with low-temperature distribution systems offer a more suitable and efficient means of heating homes.
The paper deals with the computational simulations of the performance of the hybrid ventilation system for the moderate climate, which was developed within the framework of the RESHYVENT project. The main goal of the simulations was to investigate the performance of the system in urban environment under different climatic conditions, representing different potential of natural driving forces (wind, buoyancy). The TRNSYS 15 with the TRNFlow air flow network module was employed as a simulation tool.
In recent years, indoor humidity levels are gaining greater attention in building design and operation, due to the increasing concern over moisture-related problems, such as mold growth, indoor air quality and discomfort of the occupants. At the same time, building energy consumption, especially at peak electric demand, is also becoming a significant operating cost conern. It has been suggested that besides energy recovery, the inclusion of an energy recovery ventilator (ERV) with a right-sized cooling coil can improve temperature and humidity control in buildings.
In this paper, the mathematical model of a HVAC (Heating, Ventilation and Air-Conditioning) equipment is described. This system is inserted into a computer code developed in Matlab/Simulink platform which is devoted to the analysis of building thermal behavior and HVAC closed-loop control performance. The model is presented in terms of non-linear state-space equations that represent the energy and mass balances for each HVAC component. Two control loop structures are described and analyzed. The IMC structure is used for the PID controllers tuning procedure.
Earth-to-Air Heat Exchanger (ETAHE) technology has been implemented in many mechanical ventilation systems. A literature review revealed that recent advancements in ETAHE modeling were focused on simulating heat conduction in soil. Air temperatures along the duct length were determined by calculating heat convection on the ETAHE duct surfaces using various empirical correlations. Comparison of the correlations for typical ETAHE in mechanical ventilation systems revealed that large discrepancy exists among them.
An optimal controller for auxiliary heating of passive solar buildings and commercial buildings with high internal gains is tested in simulation. Some of the most restrictive simplifications that were used in previous studies of that controller (Kummert et al., 2001) are lifted: the controller is applied to a multizone building, and a detailed model is used for the HVAC system. The model-based control algorithm is not modified.
Tall buildings pose unique challenges for simulation software and modelers. Environmental factors such as air temperature and wind speed change with altitude. The urban environment imposes additional environmental factors because of shading and reflections from surrounding buildings. The large scale of tall buildings can result in excessive input data and prohibitive run times. EnergyPlus was used to compare the energy impacts of several environmental factors that vary with altitude.
CEN TC247 has prepared draft standards for main types of room controllers. These standards include a performance testing procedure that was designed to facilitate the introduction on the market of electronic controllers.
A simplified optimization process (SOP) for determining set points is proposed and evaluated using the monitoring data and model of an existing VAV system. Controller set points, such as supply air temperature, supply duct static pressure, and chilled water supply temperature, are determined by this proposed SOP in order to minimize energy use while respecting thermal comfort. Zone air temperatures are also considered in order to obtain further energy savings.
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