Energy Impacts of Nonlinear Behavior of PCM When Applied Into Building Envelope

2012 ◽  
Author(s):  
Paulo Cesar Tabares-Velasco
Keyword(s):  
Energy Use ◽  
Phase Change Materials ◽  
Energy Savings ◽  
Peak Load ◽  
Building Energy ◽  
Building Envelope ◽  
Energy Simulation ◽  
Building Energy Simulation ◽  
Peak Reduction ◽  
The Impact

Research on phase change materials (PCM) as a potential technology to reduce peak loads and HVAC energy use in buildings has been conducted for several decades, resulting in a great deal of literature on PCM properties, temperature, and peak reduction potential. However, there are few building energy simulation programs that include PCM modeling features, and very few of these have been validated. Additionally, there is no previous research that indicates the level of accuracy when modeling PCMs from a building energy simulation perspective. This study analyzes the effects a nonlinear enthalpy profile has on thermal performance and expected energy benefits for PCM-enhanced insulation. The impact of accurately modeling realistic, nonlinear enthalpy profiles for PCMs versus simpler profiles is analyzed based on peak load reduction and energy savings using the Conduction Finite Difference (CondFD) algorithm in EnergyPlus. The PCM and CondFD models used in this study have been previously validated after intensive verification and validation done at the National Renewable Energy Laboratory. Overall, the results of this study show annual energy savings are not very sensitive to the linearization of enthalpy curve. However, hourly analysis shows that if simpler linear profiles are used, users should try to specify a melting range covering roughly 80% of the latent heat, otherwise, hourly results can differ by up to 20%.

Energy Impacts of Nonlinear Behavior of Phase Change Materials When Applied to Opaque Building Envelopes

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Paulo Cesar Tabares-Velasco
Keyword(s):  
Phase Change ◽  
Energy Use ◽  
Phase Change Materials ◽  
Energy Savings ◽  
Peak Load ◽  
Building Energy ◽  
Energy Simulation ◽  
Building Energy Simulation ◽  
Peak Reduction ◽  
The Impact

Research on phase change materials (PCM) as a potential technology to reduce peak loads and heating, ventilation and air conditioning (HVAC) energy use in buildings has been conducted for several decades, resulting in a great deal of literature on PCM properties, temperature, and peak reduction potential. However, there are few building energy simulation programs that include PCM modeling features, and very few of these have been validated. Additionally, there is no previous research that indicates the level of accuracy when modeling PCMs from a building energy simulation perspective. This study analyzes the effects a nonlinear enthalpy profile has on thermal performance and expected energy benefits for PCM-enhanced insulation. The impact of accurately modeling realistic, nonlinear enthalpy profiles for PCMs versus simpler profiles is analyzed based on peak load reduction and energy savings using the conduction finite difference (CondFD) algorithm in EnergyPlus. The PCM and CondFD models used in this study have been previously validated after intensive verification and validation done at the National Renewable Energy Laboratory. Overall, the results of this study show annual energy savings are not very sensitive to the linearization of enthalpy curve. However, hourly analysis shows that if simpler linear profiles are used, users should try to specify a melting range covering roughly 80% of the latent heat; otherwise, hourly results can differ by up to 20%.

scholarly journals The impact of building envelope retrofit measures on postwar MURBS in Toronto

2021 ◽  
Author(s):  
Sara Damyar
Keyword(s):  
Energy Consumption ◽  
Energy Saving ◽  
Energy Use ◽  
Energy Savings ◽  
Building Envelope ◽  
Simulation Software ◽  
Energy Simulation ◽  
Reduce Energy Consumption ◽  
The Impact ◽  
Current Standards

Building envelope retrofits is one of the options available to reduce energy consumption of postwar MURBs in Toronto. This study evaluates the impact of building envelope retrofits that meet current standards on energy consumption of a Toronto postwar MURB; utilizing eQUEST energy simulation software. Further upgrades also take place to evaluate how the impact of building envelope retrofits on energy use can be increased and optimized for all assemblies of building envelope and airtightness. Moreover, the retrofit strategies are ranked based on cost and energy-saving effectiveness. The results of the analysis reveal that building envelope retrofit based on OBC-2012 standards can reduce the energy consumption by up to 44%. Furthermore, the optimal RSI values of all building envelope components were found to be equal or less than code requirements which outcomes significant energy savings. Lastly, the ranking of the strategies helps to identify the best option according to the priorities of a project.

scholarly journals The impact of building envelope retrofit measures on postwar MURBS in Toronto

2021 ◽  
Author(s):  
Sara Damyar
Keyword(s):  
Energy Consumption ◽  
Energy Saving ◽  
Energy Use ◽  
Energy Savings ◽  
Building Envelope ◽  
Simulation Software ◽  
Energy Simulation ◽  
Reduce Energy Consumption ◽  
The Impact ◽  
Current Standards

Building envelope retrofits is one of the options available to reduce energy consumption of postwar MURBs in Toronto. This study evaluates the impact of building envelope retrofits that meet current standards on energy consumption of a Toronto postwar MURB; utilizing eQUEST energy simulation software. Further upgrades also take place to evaluate how the impact of building envelope retrofits on energy use can be increased and optimized for all assemblies of building envelope and airtightness. Moreover, the retrofit strategies are ranked based on cost and energy-saving effectiveness. The results of the analysis reveal that building envelope retrofit based on OBC-2012 standards can reduce the energy consumption by up to 44%. Furthermore, the optimal RSI values of all building envelope components were found to be equal or less than code requirements which outcomes significant energy savings. Lastly, the ranking of the strategies helps to identify the best option according to the priorities of a project.

scholarly journals Building Retrofitting through Coupling of Building Energy Simulation-Optimization Tool with CFD and Daylight Programs

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2180
Author(s):  
Mehrdad Rabani ◽  
Habtamu Bayera Madessa ◽  
Natasa Nord
Keyword(s):  
Energy Use ◽  
Ventilation System ◽  
Building Energy ◽  
Building Envelope ◽  
Energy Simulation ◽  
Building Energy Simulation ◽  
Visual Comfort ◽  
Indoor Climate ◽  
Building Energy Use ◽  
Air System

Simultaneous satisfaction of both thermal and visual comfort in buildings may be a challenging task. Therefore, this paper suggests a comprehensive framework for the building energy optimization process integrating computational fluid dynamics (CFD) daylight simulations. A building energy simulation tool, IDA Indoor Climate and Energy (IDA-ICE), was coupled with three open-source tools including GenOpt, OpenFOAM, and Radiance. In the optimization phase, several design variables i.e., building envelope properties, fenestration parameters, and Heating, Ventilation and Air-Conditioning (HVAC) system set points, were selected to minimize the total building energy use and simultaneously improve thermal and visual comfort. Two different scenarios were investigated for retrofitting of a generic office building located in Oslo, Norway. In the first scenario a constant air volume (CAV) ventilation system with a local radiator in each zone was used, while an all-air system equipped with a demand control ventilation (DCV) was applied in the second scenario. Findings showed that, compared to the reference design, significant reduction of total building energy use, around 77% and 79% in the first and second scenarios, was achieved respectively, and thermal and visual comfort conditions were also improved considerably. However, the overall thermal and visual comfort satisfactions were higher when all-air system was applied.

scholarly journals Influence of Lightweight Aggregate Concrete Materials on Building Energy Performance

Buildings ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 94
Author(s):  
Tara L. Cavalline ◽  
Jorge Gallegos ◽  
Reid W. Castrodale ◽  
Charles Freeman ◽  
Jerry Liner ◽  
...  
Keyword(s):  
Thermal Properties ◽  
Building Materials ◽  
Energy Savings ◽  
Lightweight Concrete ◽  
Lightweight Aggregate ◽  
Building Energy ◽  
Energy Performance ◽  
Energy Simulation ◽  
Building Energy Simulation ◽  
Building Energy Performance

Due to their porous nature, lightweight aggregates have been shown to exhibit thermal properties that are advantageous when used in building materials such as lightweight concrete, grout, mortar, and concrete masonry units. Limited data exist on the thermal properties of materials that incorporate lightweight aggregate where the pore system has not been altered, and very few studies have been performed to quantify the building energy performance of structures constructed using lightweight building materials in commonly utilized structural and building envelope components. In this study, several lightweight concrete and masonry building materials were tested to determine the thermal properties of the bulk materials, providing more accurate inputs to building energy simulation than have previously been used. These properties were used in EnergyPlus building energy simulation models for several types of commercial structures for which materials containing lightweight aggregates are an alternative commonly considered for economic and aesthetic reasons. In a simple model, use of sand lightweight concrete resulted in prediction of 15–17% heating energy savings and 10% cooling energy savings, while use of all lightweight concrete resulted in prediction of approximately 35–40% heating energy savings and 30% cooling energy savings. In more complex EnergyPlus reference models, results indicated superior thermal performance of lightweight aggregate building materials in 48 of 50 building energy simulations. Predicted energy savings for the five models ranged from 0.2% to 6.4%.

Three-Dimensional Numerical Evaluation of Thermal Performance of Uninsulated Wall Assemblies

2011 ◽  
Author(s):  
El Hassan Ridouane ◽  
Marcus V. A. Bianchi
Keyword(s):  
Thermal Performance ◽  
Energy Savings ◽  
Three Dimensional ◽  
Building Energy ◽  
Energy Performance ◽  
Energy Simulation ◽  
Cavity Surface ◽  
Building Energy Simulation ◽  
Simulation Tools ◽  
Whole Building Energy Simulation

Uninsulated wall assemblies are typical in older homes, as many were built before building codes required insulation. Building engineers need to understand the thermal performance of these assemblies as they consider home energy upgrades if they are to properly predict pre-upgrade performance and, consequently, prospective energy savings from the upgrade. Most whole-building energy simulation tools currently use simplified, 1D characterizations of building envelopes and assume a fixed thermal resistance that does not vary over a building’s temperature range. This study describes a detailed 3D computational fluid dynamics model that evaluates the thermal performance of uninsulated wall assemblies. It accounts for conduction through framing, convection, and radiation and allows for material property variations with temperature. Parameters that were varied include ambient outdoor temperature and cavity surface emissivity. The results may serve as input for building energy simulation tools that model the temperature-dependent energy performance of homes with uninsulated walls.

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