Publications
2019
Ben-David, Tom; Rackes, Adams; Lo, L. James; Wen, Jin; Waring, Michael S.
In: Building and Environment, vol. 166, pp. 106314, 2019, ISSN: 0360-1323.
Abstract | Links | BibTeX | Tags: Building energy, Healthy buildings, Occupant performance, Optimization, Ventilation control
@article{BENDAVID2019106314,
title = {Optimizing ventilation: Theoretical study on increasing rates in offices to maximize occupant productivity with constrained additional energy use},
author = {Tom Ben-David and Adams Rackes and L. James Lo and Jin Wen and Michael S. Waring},
url = {https://www.sciencedirect.com/science/article/pii/S0360132319305244},
doi = {https://doi.org/10.1016/j.buildenv.2019.106314},
issn = {0360-1323},
year = {2019},
date = {2019-01-01},
journal = {Building and Environment},
volume = {166},
pages = {106314},
abstract = {Ventilation affects building energy use and indoor air quality, with minimum rates prescribed by standards. However, research has demonstrated positive outcomes associated with increasing ventilation, including occupant productivity from increased work performance and reduced absenteeism. Herein, a novel ventilation strategy was proposed and simulated for offices, which optimized day-averaged ventilation rates over an annual time horizon to provide maximal amounts of outdoor air and so maximize occupant productive work hours, within varying energy use constraints. Energy use and productivity were often influenced by ventilation oppositely, so results were Pareto optimal. This optimization methodology was simulated in three locations for an average- and high-performance small office building, considering users with varying levels of confidence in ventilation-productivity relationships. To contextualize potential optimization impacts, four annual energy budgets were first determined for a typical year at constant ventilation rates of 8.5, 10, 20, and 30 L/s/occupant, and then for those four cases, day-averaged ventilation rates were optimized over annual trajectories considering the constrained energy budgets. Among all simulated cases, lost productive hours due to lower ventilation at constant rates were halved when using the optimized higher annual rates, with a gain of ~20 h/year per occupant on average, amounting to approximately $48/m2 at standard occupant density and mean wage. Offline optimization results were used to develop heuristic rules to predict a ventilation rate for any single day based on weather forecast that would adhere to a building- and climate-specific Pareto optimization, opening avenues for future control strategies that use this framework in real buildings.},
keywords = {Building energy, Healthy buildings, Occupant performance, Optimization, Ventilation control},
pubstate = {published},
tppubtype = {article}
}
Ventilation affects building energy use and indoor air quality, with minimum rates prescribed by standards. However, research has demonstrated positive outcomes associated with increasing ventilation, including occupant productivity from increased work performance and reduced absenteeism. Herein, a novel ventilation strategy was proposed and simulated for offices, which optimized day-averaged ventilation rates over an annual time horizon to provide maximal amounts of outdoor air and so maximize occupant productive work hours, within varying energy use constraints. Energy use and productivity were often influenced by ventilation oppositely, so results were Pareto optimal. This optimization methodology was simulated in three locations for an average- and high-performance small office building, considering users with varying levels of confidence in ventilation-productivity relationships. To contextualize potential optimization impacts, four annual energy budgets were first determined for a typical year at constant ventilation rates of 8.5, 10, 20, and 30 L/s/occupant, and then for those four cases, day-averaged ventilation rates were optimized over annual trajectories considering the constrained energy budgets. Among all simulated cases, lost productive hours due to lower ventilation at constant rates were halved when using the optimized higher annual rates, with a gain of ~20 h/year per occupant on average, amounting to approximately $48/m2 at standard occupant density and mean wage. Offline optimization results were used to develop heuristic rules to predict a ventilation rate for any single day based on weather forecast that would adhere to a building- and climate-specific Pareto optimization, opening avenues for future control strategies that use this framework in real buildings.
2005
Gao, Ji; Sun, Ying; Wen, Jin; Smith, Theodore F.
An experimental study of energy consumption and thermal comfort for electric and hydronic reheats Journal Article
In: Energy and Buildings, vol. 37, no. 3, pp. 203-214, 2005, ISSN: 0378-7788.
Abstract | Links | BibTeX | Tags: Building energy, Electric reheat, Experimental data, Hydronic reheat
@article{GAO2005203,
title = {An experimental study of energy consumption and thermal comfort for electric and hydronic reheats},
author = {Ji Gao and Ying Sun and Jin Wen and Theodore F. Smith},
url = {https://www.sciencedirect.com/science/article/pii/S0378778804001999},
doi = {https://doi.org/10.1016/j.enbuild.2004.05.012},
issn = {0378-7788},
year = {2005},
date = {2005-01-01},
journal = {Energy and Buildings},
volume = {37},
number = {3},
pages = {203-214},
abstract = {This paper compares the performances of electric and hydronic reheat modes for variable-air-volume units using experimental data for a building. The comparisons are made based on the daily energy consumption associated with each reheat mode and comfort performances within a building zone. Data are collected from a full-scale heating, ventilating, and air conditioning system. Weather conditions are considered and the corresponding energy distributions are evaluated. The results showed that the energy for the air handling unit using hydronic reheat is lower than that using electric reheat by about 24% when the air handling unit is operated in either the mechanical or mechanical and economizer cooling mode and 33% for the economizer cooling mode. The reheat energy for the variable-air-volume units using hydronic reheat is lower by about 75% than for electric reheat for either the mechanical or mechanical and economizer cooling mode and 54% for the economizer cooling mode. The main reason for the low-energy consumption using hydronic reheat is attributed to the lower requirement for the minimum air flow across the reheat coil. Electric reheat provides a slightly cooler comfort environment than that for hydronic reheat.},
keywords = {Building energy, Electric reheat, Experimental data, Hydronic reheat},
pubstate = {published},
tppubtype = {article}
}
This paper compares the performances of electric and hydronic reheat modes for variable-air-volume units using experimental data for a building. The comparisons are made based on the daily energy consumption associated with each reheat mode and comfort performances within a building zone. Data are collected from a full-scale heating, ventilating, and air conditioning system. Weather conditions are considered and the corresponding energy distributions are evaluated. The results showed that the energy for the air handling unit using hydronic reheat is lower than that using electric reheat by about 24% when the air handling unit is operated in either the mechanical or mechanical and economizer cooling mode and 33% for the economizer cooling mode. The reheat energy for the variable-air-volume units using hydronic reheat is lower by about 75% than for electric reheat for either the mechanical or mechanical and economizer cooling mode and 54% for the economizer cooling mode. The main reason for the low-energy consumption using hydronic reheat is attributed to the lower requirement for the minimum air flow across the reheat coil. Electric reheat provides a slightly cooler comfort environment than that for hydronic reheat.