Abstract
As most residents spend more than 90% of their time in buildings, acceptable and reasonable control of both indoor thermal comfort and air quality is imperative to ensure occupants’ health status and work productivity. However, current control strategies generally take either thermal comfort or indoor air quality as a single loop, rather than the concurrent control of two. To analyze their mutual influence, this study investigated the performance of three multi-control approaches, i.e., proportional integral derivative (PID) control of thermal comfort and a fixed outdoor air ratio, PID control of thermal comfort and design outdoor air rate, and PID control of thermal comfort and occupancy-based demand-controlled ventilation. As a pilot study, three typical control methods were implemented to a multi-zone building via OpenModelica modeling. The results indicate that indoor air temperature can be well-maintained under three control methods, however, the CO2 concentration under the fixed outdoor air ratio was over 1000 ppm, leading to poor indoor air quality. The control strategy with the design outdoor air rate could not properly ensure the CO2 concentration, due to the over-ventilated or under-ventilated phenomena, subsequently resulting in unnecessary energy waste. The occupancy-based demand controlled ventilation could maintain the CO2 concentration under the set-point with an intermediate power energy utilization.
Highlights
Among building energy consumers, heat, ventilation, and air conditioning (HVAC) systems dominate more than 40% of power consumption, to maintain acceptable indoor air quality (IAQ)and thermal comfort (TC) status [1,2]
The indoor air temperature and CO2 concentration were uniformly distributed inside the room; We assumed there were no natural ventilation of all rooms with good air tightness; The heat transfer through the building envelope were ignored, and heat gains for all zones were assumed to come from occupants, lights, and computers; Under the first two scenarios, two kinds of occupancy profiles were assessed, i.e., the designed occupancy recommended by the ASHRAE standards and the real occupancy profile
The indoor air temperature and CO2 concentration level of six zones were simulated via OpenModelica platform
Summary
Heat, ventilation, and air conditioning (HVAC) systems dominate more than 40% of power consumption, to maintain acceptable indoor air quality (IAQ). Thermal comfort (TC) status [1,2] These two objectives are consistently urgent and essential issues for human health, since most people spend more than 90% of their time inside buildings [3,4]. HVAC systems might compromise IAQ and TC, while strict construction of healthy and comfortable indoor environment usually demands more energy consumptions. The energy-efficient control strategies of IAQ and TC has gained the attention of researchers, to reduce energy consumption without compromising thermal comfort [8,9] and IAQ [10,11], which shows that these energy efficient control strategies have the potential to save 14% to 34% of building energy
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