Simulating the Use of CO2 Concentration Inputs for Controlling Temperature in a Hydronic Radiant System

2017 ◽  
Author(s):  
Michael Sterman ◽  
Melody Baglione
Keyword(s):  
High Performance ◽  
Energy Use ◽  
Numerical Models ◽  
Co2 Concentration ◽  
Ann Model ◽  
Heating And Cooling ◽  
Air Temperatures ◽  
Demand Fluctuations ◽  
Carbon Dioxide Co2 ◽  
And Control

Incorporating predictive control into heating, ventilation and air conditioning (HVAC) systems has the potential to improve occupancy comfort and reduce energy use. This paper simulates the novel use of carbon dioxide (CO2) concentration inputs to augment temperature prediction and control. An artificial neural network (ANN) model and a least mean squares (LMS) filtering algorithm are used to simulate the temperature and control of a classroom in a high performance academic building with hydronic radiant heating and cooling panels. Numerical models are populated with variables that affect the heat energy entering, leaving, and being generated in a classroom. These variables include indoor and outdoor air temperature, radiant water and supply air temperatures, and classroom CO2 concentrations. The models are compared and then used to simulate the effect of a new control system that inputs CO2 measurements to account for the heat being generated by occupants of the controlled space. Simulation results suggest that augmenting HVAC control systems with CO2 measurements has the potential to improve temperature regulation by anticipating heating and cooling demand fluctuations in spaces with abrupt changes in occupancy.

scholarly journals Indoor Environmental Quality Evaluation of Lecture Classrooms in an Institutional Building in a Cold Climate

2019 ◽  
Vol 11 (23) ◽  
pp. 6591 ◽  
Author(s):  
Lexuan Zhong ◽  
Jing Yuan ◽  
Brian Fleck
Keyword(s):  
Environmental Quality ◽  
Co2 Concentration ◽  
Sound Level ◽  
Cold Climate ◽  
Indoor Environmental Quality ◽  
Ann Model ◽  
University Of Alberta ◽  
Artificial Neural Network Ann ◽  
Carbon Dioxide Co2 ◽  
The University

In this paper, ventilation, indoor air quality (IAQ), thermal and acoustic conditions, and lighting were studied to evaluate the indoor environmental quality (IEQ) in an institutional building at the University of Alberta in Edmonton, Canada. This study examined IEQ parameters, including pressure, illuminance, acoustics, carbon dioxide (CO2) concentration, temperature, and humidity, with appropriate monitors allocated during a lecture (duration 50 min or 80 min) in four lecture classrooms repeatedly (N = 99) from October 2018 to March 2019 with the objectives of providing a comprehensive analysis of interactions between IEQ parameters. The classroom environments were maintained at 23 ± 1 °C and 33% ± 3% RH during two-season measurements. Indoor mean CO2 concentrations were 550–1055 ppm, and a mean sound level of 58 ± 3 dBA was observed. The air change rates were configured at 1.3–6.5 per hour based on continuous CO2 measurements and occupant loads in the lectures. A variance analysis indicated that the within-lecture classroom variations in most IEQ parameters exceeded between-lecture classrooms. A multilayer artificial neural network (ANN) model was developed on the basis of feedforward networks with a backpropagation algorithm. ANN results demonstrated the importance of the sequence of covariates on indoor conditions (temperature, RH, and CO2 level): Air change rate (ACR) > room operations (occupant number and light system) > outdoor conditions.

Design Optimization of Energy Efficient Office Buildings in Tunisia

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Pyeongchan Ihm ◽  
Moncef Krarti
Keyword(s):  
Energy Efficiency ◽  
Energy Efficient ◽  
High Performance ◽  
Energy Use ◽  
Cost Effective ◽  
Energy Performance ◽  
High Energy ◽  
Office Buildings ◽  
Optimization Approach ◽  
Heating And Cooling

Optimal and cost-effective energy efficiency design and operation options are evaluated for office buildings in Tunisia. In the analysis, several design and operation features are considered including orientation, window location and size, high performance glazing types, wall and roof insulation levels, energy efficient lighting systems, daylighting controls, temperature settings, and energy efficient heating and cooling systems. First, the results of the optimization results from a sequential search technique are compared against those obtained by a more time consuming brute-force optimization approach. Then, the optimal design features for a prototypical office building are determined for selected locations in Tunisia. The optimization results indicate that utilizing daylighting controls, energy efficient lighting fixtures, and low-e double glazing, and roof insulation are required energy efficiency measures to design high energy performance office buildings throughout climatic zones in Tunisia. In particular, it is found that implementing these measures can cost-effectively reduce the annual energy use by 50% compared to the current design practices of office buildings in Tunisia.

scholarly journals Spatio-temporal variations of cave-air CO2 concentrations in two Croatian show caves: Natural vs. anthropogenic controls

2021 ◽  
Vol 74 (3) ◽  
pp. 273-286
Author(s):  
Maša Surić ◽  
◽  
Robert Lončarić ◽  
Matea Kulišić ◽  
Lukrecija Sršen ◽  
...  
Keyword(s):  
Co2 Flux ◽  
Co2 Concentration ◽  
Temporal Variations ◽  
Natural Processes ◽  
Air Temperatures ◽  
Show Caves ◽  
Spatio Temporal ◽  
Bora Wind ◽  
Carbon Dioxide Co2 ◽  
The Right

Carbon dioxide (CO2) concentration (CDC) plays an important role in karst processes, governing both carbonate deposition and dissolution, affecting not only natural processes, but also human activities in caves adapted for tourism. Its variations due to various controlling parameters was observed from 2017 to 2021 in two Croatian show caves (Manita peć and Modrič) where we examined inter- and within-cave correlation of internal aerology regarding the sources, sinks and transport mechanism of CDC in a karst conduit setting. In both caves, the main sources of CO2 are: i) plant and microbial activity i.e. root respiration and organic matter decay within soil horizons and fractured epikarst, and ii) degassing from CO2-rich percolation water. The main sink of CO2 is dilution with outside air due to cave ventilation. Chimney-effect driven ventilation controlled by seasonal differences between surface and cave air temperatures shows winter (Tout<Tcave) and summer (Tout>Tcave ) ventilation regime, which are modulated by the geometry of cave passages, the transmissivity of the overlying epikarst, and occasionally by the external winds, especially the gusty north-eastern bora wind. In these terms, the Modrič Cave appears to be more confined and less ventilated, with a substantial CDC difference between the left (550-7200 ppm) and right (1475- >10,000 ppm) passages. The Manita peć Cave is, in contrast, ventilated almost year-round, having 7 months of CDC equilibrated with the outside atmosphere and the highest summer CDC values of ~1410 ppm. In both caves, at the current level of tourist use, anthropogenic CO2 flux is not a matter of concern for cave conservation. In turn, in the innermost part of the right Modrič Cave passage visitors’ health might be compromised, but the tourists are allowed only in the left passage. Speleothem growth rate, recognized as a useful palaeoenvironmental proxy for speleothem-based palaeoclimate studies, strongly depends on CDC variations, so the high CDCs recorded in the Modrič Cave indicate the potential periods with no speleothem deposition due to the hampered degassing of CO2 from the dripping groundwater. The opposite effect i.e. enhanced ventilation (that supports calcite precipitation) during the windy glacials/stadials, as well as substantial vegetational changes must also be taken into consideration when interpreting environmental records from spelean calcite.

scholarly journals Nanomaterial-Based CO2 Sensors

Nanomaterials ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 2251
Author(s):  
Marwan Y. Rezk ◽  
Jyotsna Sharma ◽  
Manas Ranjan Gartia
Keyword(s):  
Carbon Dioxide ◽  
High Performance ◽  
State Of The Art ◽  
Co2 Concentration ◽  
Industrial Applications ◽  
Future Trends ◽  
Chemical Safety ◽  
Safety Control ◽  
Carbon Dioxide Co2 ◽  
Application Fields

The detection of carbon dioxide (CO2) is critical for environmental monitoring, chemical safety control, and many industrial applications. The manifold application fields as well as the huge range of CO2 concentration to be measured make CO2 sensing a challenging task. Thus, the ability to reliably and quantitatively detect carbon dioxide requires vastly improved materials and approaches that can work under different environmental conditions. Due to their unique favorable chemical, optical, physical, and electrical properties, nanomaterials are considered state-of-the-art sensing materials. This mini-review documents the advancement of nanomaterial-based CO2 sensors in the last two decades and discusses their strengths, weaknesses, and major applications. The use of nanomaterials for CO2 sensing offers several improvements in terms of selectivity, sensitivity, response time, and detection, demonstrating the advantage of using nanomaterials for developing high-performance CO2 sensors. Anticipated future trends in the area of nanomaterial-based CO2 sensors are also discussed in light of the existing limitations.

scholarly journals Effects of Specific Parameters on Simulations of Energy Use and Air Temperatures in Offices Equipped with Radiant Heating/Cooling Panels

2019 ◽  
Vol 9 (21) ◽  
pp. 4609 ◽  
Author(s):  
Sabina Jordan ◽  
Jože Hafner ◽  
Martina Zbašnik-Senegačnik ◽  
Andraž Legat
Keyword(s):  
Simulation Model ◽  
Indoor Air ◽  
Energy Use ◽  
Small Degree ◽  
Radiant Heating ◽  
Feedback Information ◽  
Heating And Cooling ◽  
Air Temperatures ◽  
Frequency Magnitude ◽  
Real Building

When creating a simulation model to assess the performance of buildings, there is usually a lack of feedback information. Only in the case of measurements of a real building is a direct comparison of the measured values and simulated results possible. Parameter data related to users’ behavior or other events can also be obtained. Their evaluated frequency, magnitude and duration, along with boundary conditions, are crucial for the results. It is clear that none of them can be predicted very accurately. Most of them, however, are needed for computer modeling. In this paper we analyzed the well-defined TRNSYS simulation model of offices equipped with radiant ceiling panels for heating and cooling. The model was based on real case offices and was validated based on measurements for 1 year. The analysis included simulations in order to define what effect the parameters related mainly to users have on the energy use and the indoor air temperatures. The study confirmed that specific human activities influence the annual energy use to a relatively small degree and that their effects often counteract. It also confirmed the even more important fact that although small, these activities can influence the thermal comfort of users. It is believed that despite the fact that this research was based on an analysis of offices equipped with radiant ceiling panels, most of the results could be applied generally.

scholarly journals Improving the Efficiency of Thermal Energy Use When Heating Buildings Through the Introduction of Technologies «Smart Home»

2018 ◽  
Keyword(s):  
Thermal Energy ◽  
Smart Home ◽  
Heat Supply ◽  
Energy Use ◽  
Economic Effect ◽  
Thermal Conditions ◽  
Natural Object ◽  
Air Temperatures ◽  
National University ◽  
Carbon Dioxide Co2

Purpose. Investigation of the effectiveness of application in the heating systems of administrative, residential, industrial and other buildings of automated thermal management systems for premises using the «smart home» technology Methods. Analysis and synthesis of information, mathematical modeling of the heat supply process of a building, statistical data processing, a computational experiment to assess the effectiveness of the use of «smart home» technologies in heat supply systems. Results. A natural object was selected and investigated for the introduction of energy-saving technologies − a 3-storey fragment of the O.M. Beketov National University of Urban Economy in Kharkiv administrative building with a total heated area of 225,3 m2; investigated: structure, principle of operation, efficiency of the use of an automated control system for thermal conditions of the premises - HERZ Smart Comfort. Conclusions. The efficiency of using the HERZ Smart Comfort system was assessed according to the following criteria: the relative and absolute values of the decrease in thermal energy for heating a building - a natural object, the reduction in atmospheric emissions of carbon dioxide - CO2, and the economic efficiency from saving thermal energy.The heat loss calculation was performed at round-the-clock temperature in premises +18 ° C for average monthly outside air temperatures in Kharkov during the heating seasons 1981-2016. It has been established that the use of «smart home» technologies allows reducing the costs for heating a natural object during the heating season by 16.6%, which is 4709 kWh and leads to a reduction in CO2 emissions from the production of heat in the amount of 0.95 tons/year; The economic effect in this case is 6430 UAH.

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