scholarly journals Urban Microclimate Analysis for High Performance Office Buildings

2021 ◽  
Author(s):  
◽  
Jing Li
Keyword(s):  
Boundary Layer ◽  
Temperature Gradient ◽  
Air Temperature ◽  
Energy Performance ◽  
Simulation System ◽  
Office Buildings ◽  
Building Performance ◽  
Urban Microclimate ◽  
Detailed Modelling ◽  
Vertical Variations

<p>This research explored whether urban microclimate analysis has significant impacts on high-performance office buildings. It studied the effects of detailed three-dimensional urban microclimate modelling on building performance simulation. The feasibility and necessity of developing an urban microclimate simulation system were explored.  Currently, individual parameters of urban microclimate are modelled by individual programs. However, there was no individual software that could model airflow, Urban Heat Island (UHI) effects and building energy performance at the same time. A simulation system made it possible to model these features of urban microclimate together. Apart from the reliability of programs, accessibility and compatibility were also important for building a simulation system. The goal of this research was to determine the relative scale of the likely microclimate impacts on energy performance, not to present a system that made a precise estimate of these effects in combination. The scale of the variations of results due to changes of urban microclimate parameters were more significant than the values of the results themselves. This is because the focus of the research was on determining to what degree each parameter made a difference in the building performance. The goal was to determine whether it is necessary to model every urban microclimate parameter when their individual effects are combined. The parameters of urban microclimates included horizontal parameters like urban wind and UHI, and vertical parameters like lapse rate, urban boundary layer. In this research, the urban microclimate was modelled in three dimensions, but the process of urban microclimate modelling was time-consuming. This leaded to one of the central questions of the thesis: is there value in the time spent? How big is the scale of the influence of urban microclimate detailed modelling on the prediction of building performance? Is it worthwhile to model three-dimensional urban microclimates? When there is not enough time to calibrate all parameters, what are the parameters’ priorities?  A prototypical high-rise office building was modelled based on the data about high-rise office buildings in London. Firstly, the effects of the horizontal parameters were explored. The UHI has larger effects than urban wind. Secondly, the significance of vertical parameters was also explored. At a lower floor, the influence of the wind speed exponent and the boundary layer thickness on building performance simulation is bigger than that of the air temperature gradient coefficient. However, at a higher floor, the influence of the air temperature gradient coefficient is bigger. Finally, a multilayer modelling method was developed to explore the inconsistent vertical variations. The multilayer model consists of the portion in the Urban Canopy Layer (UCL) and the portion in the Urban Boundary Layer (UBL). The effects of vertical variations increase with the distance between the studied height and the UCL height. The feasibility and necessity of developing the simulation system of urban microclimate detailed modelling were demonstrated in the climate of London. In different climates, is it still necessary? The effects of urban microclimate detailed modelling on windy, continental, and tropical climates were also studied.  The necessity of urban microclimate detailed modelling has been demonstrated because the combined effects produced around -25% change in London’s climate and Wellington’ climate at most. In Beijing’s climate the change was around -6% and in Singapore’s climate was 2.2% at most. The UHI has a big impact in moderate and continental climates. In a continental climate, there is a big difference in the monthly thermal load prediction. It helps engineers optimize the design of heating in winter and cooling in summer. The effects of urban wind in a windy climate are bigger than those in other cities. The precision of vertical variations has very limited influence, especially in the tropical climate. The air temperature gradient in a tropical climate changed thermal load prediction a lot. The parameters’ priorities in different climates are different. There is no consistent pattern of one factor being less important than the others across all these climates. Therefore, to model the thermal performance of tall buildings in dense urban environments it is necessary to develop a simulation system that can model the Urban Heat Island, and the differences in 3D of variations of temperature, sun and wind within and above the Urban Canopy Layer. Finally, from the one case study examined, modelling urban microclimate in detail is more important for natural ventilation systems than for HVAC systems.  Overall, the simulation system of urban microclimate modelling was developed gradually. It is necessary to develop the simulation system to approach a real urban circumstance. The accuracy of the detailed urban microclimate model depends on the engineers’ requirements. The priority of urban microclimate parameters depends on climatic features.</p>

scholarly journals Urban Microclimate Analysis for High Performance Office Buildings

2021 ◽  
Author(s):  
◽  
Jing Li
Keyword(s):  
Boundary Layer ◽  
Temperature Gradient ◽  
Air Temperature ◽  
Energy Performance ◽  
Simulation System ◽  
Office Buildings ◽  
Building Performance ◽  
Urban Microclimate ◽  
Detailed Modelling ◽  
Vertical Variations

<p>This research explored whether urban microclimate analysis has significant impacts on high-performance office buildings. It studied the effects of detailed three-dimensional urban microclimate modelling on building performance simulation. The feasibility and necessity of developing an urban microclimate simulation system were explored.  Currently, individual parameters of urban microclimate are modelled by individual programs. However, there was no individual software that could model airflow, Urban Heat Island (UHI) effects and building energy performance at the same time. A simulation system made it possible to model these features of urban microclimate together. Apart from the reliability of programs, accessibility and compatibility were also important for building a simulation system. The goal of this research was to determine the relative scale of the likely microclimate impacts on energy performance, not to present a system that made a precise estimate of these effects in combination. The scale of the variations of results due to changes of urban microclimate parameters were more significant than the values of the results themselves. This is because the focus of the research was on determining to what degree each parameter made a difference in the building performance. The goal was to determine whether it is necessary to model every urban microclimate parameter when their individual effects are combined. The parameters of urban microclimates included horizontal parameters like urban wind and UHI, and vertical parameters like lapse rate, urban boundary layer. In this research, the urban microclimate was modelled in three dimensions, but the process of urban microclimate modelling was time-consuming. This leaded to one of the central questions of the thesis: is there value in the time spent? How big is the scale of the influence of urban microclimate detailed modelling on the prediction of building performance? Is it worthwhile to model three-dimensional urban microclimates? When there is not enough time to calibrate all parameters, what are the parameters’ priorities?  A prototypical high-rise office building was modelled based on the data about high-rise office buildings in London. Firstly, the effects of the horizontal parameters were explored. The UHI has larger effects than urban wind. Secondly, the significance of vertical parameters was also explored. At a lower floor, the influence of the wind speed exponent and the boundary layer thickness on building performance simulation is bigger than that of the air temperature gradient coefficient. However, at a higher floor, the influence of the air temperature gradient coefficient is bigger. Finally, a multilayer modelling method was developed to explore the inconsistent vertical variations. The multilayer model consists of the portion in the Urban Canopy Layer (UCL) and the portion in the Urban Boundary Layer (UBL). The effects of vertical variations increase with the distance between the studied height and the UCL height. The feasibility and necessity of developing the simulation system of urban microclimate detailed modelling were demonstrated in the climate of London. In different climates, is it still necessary? The effects of urban microclimate detailed modelling on windy, continental, and tropical climates were also studied.  The necessity of urban microclimate detailed modelling has been demonstrated because the combined effects produced around -25% change in London’s climate and Wellington’ climate at most. In Beijing’s climate the change was around -6% and in Singapore’s climate was 2.2% at most. The UHI has a big impact in moderate and continental climates. In a continental climate, there is a big difference in the monthly thermal load prediction. It helps engineers optimize the design of heating in winter and cooling in summer. The effects of urban wind in a windy climate are bigger than those in other cities. The precision of vertical variations has very limited influence, especially in the tropical climate. The air temperature gradient in a tropical climate changed thermal load prediction a lot. The parameters’ priorities in different climates are different. There is no consistent pattern of one factor being less important than the others across all these climates. Therefore, to model the thermal performance of tall buildings in dense urban environments it is necessary to develop a simulation system that can model the Urban Heat Island, and the differences in 3D of variations of temperature, sun and wind within and above the Urban Canopy Layer. Finally, from the one case study examined, modelling urban microclimate in detail is more important for natural ventilation systems than for HVAC systems.  Overall, the simulation system of urban microclimate modelling was developed gradually. It is necessary to develop the simulation system to approach a real urban circumstance. The accuracy of the detailed urban microclimate model depends on the engineers’ requirements. The priority of urban microclimate parameters depends on climatic features.</p>

scholarly journals Air Distribution and Air Handling Unit Configuration Effects on Energy Performance in an Air-Heated Ice Rink Arena

Energies ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 693 ◽  
Author(s):  
Mehdi Taebnia ◽  
Sander Toomla ◽  
Lauri Leppä ◽  
Jarek Kurnitski
Keyword(s):  
Temperature Gradient ◽  
Air Temperature ◽  
Indoor Air ◽  
Energy Demand ◽  
Energy Performance ◽  
Air Distribution ◽  
Air Handling Unit ◽  
Cooling Coil ◽  
Indoor Conditions ◽  
Cooling Energy Demand

Indoor ice rink arenas are among the foremost consumers of energy within building sector due to their exclusive indoor conditions. A single ice rink arena may consume energy of up to 3500 MWh annually, indicating the potential for energy saving. The cooling effect of the ice pad, which is the main source for heat loss, causes a vertical indoor air temperature gradient. The objective of the present study is twofold: (i) to study vertical temperature stratification of indoor air, and how it impacts on heat load toward the ice pad; (ii) to investigate the energy performance of air handling units (AHU), as well as the effects of various AHU layouts on ice rinks’ energy consumption. To this end, six AHU configurations with different air-distribution solutions are presented, based on existing arenas in Finland. The results of the study verify that cooling energy demand can significantly be reduced by 38 percent if indoor temperature gradient approaches 1 °C/m. This is implemented through air distribution solutions. Moreover, the cooling energy demand for dehumidification is decreased to 59.5 percent through precisely planning the AHU layout, particularly at the cooling coil and heat recovery sections. The study reveals that a more customized air distribution results in less stratified indoor air temperature.

scholarly journals An evaluation of the effects of thermal insulation levels on the energy performance of New Zealand office buildings- exploring the impact of building attributes on the performance of thermal insulation

2021 ◽  
Author(s):  
◽  
Brittany Grieve
Keyword(s):  
Energy Consumption ◽  
New Zealand ◽  
Thermal Insulation ◽  
Building Energy ◽  
Energy Performance ◽  
Building Envelope ◽  
Office Buildings ◽  
Building Performance ◽  
Energy Models ◽  
The Impact

<p>This thesis explored the impact of thermal insulation on the energy performance of New Zealand air-conditioned commercial office buildings. A sample of calibrated energy models constructed using real building performance data and construction information was used to ensure that the results produced were as realistic as possible to the actual building performance of New Zealand commercial office buildings. The aim was to assess how different climates and building attributes impact thermal insulation's ability to reduce energy consumption in New Zealand commercial office buildings.   Driven by the ever increasing demands for healthier, more comfortable, more sustainable buildings, building regulations have steadily increased the levels of insulation they require in new buildings over time. Improving the thermal properties of the building envelope with the addition of thermal insulation is normally used to reduce the amount of heating and cooling energy a building requires. Thermal insulation reduces the conductive heat transfer through the building envelope and with a higher level of thermal resistance, the less heat would transfer through the envelope. Consequently, the common expectation is that the addition of thermal insulation to the building envelope will always reduce energy consumption. However, this assumption is not always the case. For internal load dominated buildings located in certain climates, the presence of any or a higher level of thermal insulation may prevent heat loss through the wall, increasing the cooling energy required. This issue is thought to have not been directly examined in literature until 2008. However, an early study undertaken in New Zealand in 1996 found that for climates similar or warmer than Auckland, the addition of insulation could be detrimental to an office building's energy efficiency due to increased cooling energy requirements.  The energy performance of a sample of 13 real New Zealand office building energy models with varying levels of thermal insulation in 8 locations was examined under various scenarios. A parametric method of analysis using building energy modelling was used to assess the energy performance of the buildings. Buildings were modelled as built and standardised with the current NZS4243:2007 regulated and assumed internal load and operational values. The effect the cooling thermostat set point temperature had on the buildings' energy performance at varying levels of insulation was also tested.   The study concluded that the use of thermal insulation in New Zealand office buildings can cause an increase in cooling energy for certain types of buildings in any of the eight locations and thermal insulation levels explored in the study. The increase in cooling energy was significant enough to increase the total energy consumption of two buildings when modelled as built. These buildings were characterised by large internal loads, low performance windows with high window to wall ratios and low surface to volume ratios. The current minimum thermal resistance requirements were found to not be effective for a number of buildings in North Island locations.</p>

scholarly journals An evaluation of the effects of thermal insulation levels on the energy performance of New Zealand office buildings- exploring the impact of building attributes on the performance of thermal insulation

2021 ◽  
Author(s):  
◽  
Brittany Grieve
Keyword(s):  
Energy Consumption ◽  
New Zealand ◽  
Thermal Insulation ◽  
Building Energy ◽  
Energy Performance ◽  
Building Envelope ◽  
Office Buildings ◽  
Building Performance ◽  
Energy Models ◽  
The Impact

<p>This thesis explored the impact of thermal insulation on the energy performance of New Zealand air-conditioned commercial office buildings. A sample of calibrated energy models constructed using real building performance data and construction information was used to ensure that the results produced were as realistic as possible to the actual building performance of New Zealand commercial office buildings. The aim was to assess how different climates and building attributes impact thermal insulation's ability to reduce energy consumption in New Zealand commercial office buildings.   Driven by the ever increasing demands for healthier, more comfortable, more sustainable buildings, building regulations have steadily increased the levels of insulation they require in new buildings over time. Improving the thermal properties of the building envelope with the addition of thermal insulation is normally used to reduce the amount of heating and cooling energy a building requires. Thermal insulation reduces the conductive heat transfer through the building envelope and with a higher level of thermal resistance, the less heat would transfer through the envelope. Consequently, the common expectation is that the addition of thermal insulation to the building envelope will always reduce energy consumption. However, this assumption is not always the case. For internal load dominated buildings located in certain climates, the presence of any or a higher level of thermal insulation may prevent heat loss through the wall, increasing the cooling energy required. This issue is thought to have not been directly examined in literature until 2008. However, an early study undertaken in New Zealand in 1996 found that for climates similar or warmer than Auckland, the addition of insulation could be detrimental to an office building's energy efficiency due to increased cooling energy requirements.  The energy performance of a sample of 13 real New Zealand office building energy models with varying levels of thermal insulation in 8 locations was examined under various scenarios. A parametric method of analysis using building energy modelling was used to assess the energy performance of the buildings. Buildings were modelled as built and standardised with the current NZS4243:2007 regulated and assumed internal load and operational values. The effect the cooling thermostat set point temperature had on the buildings' energy performance at varying levels of insulation was also tested.   The study concluded that the use of thermal insulation in New Zealand office buildings can cause an increase in cooling energy for certain types of buildings in any of the eight locations and thermal insulation levels explored in the study. The increase in cooling energy was significant enough to increase the total energy consumption of two buildings when modelled as built. These buildings were characterised by large internal loads, low performance windows with high window to wall ratios and low surface to volume ratios. The current minimum thermal resistance requirements were found to not be effective for a number of buildings in North Island locations.</p>

scholarly journals Efficient Shading Device as an Important Part of Daylightophil Architecture; a Designerly Framework of High-Performance Architecture for an Office Building in Tehran

Energies ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 8272
Author(s):  
Hassan Bazazzadeh ◽  
Barbara Świt-Jankowska ◽  
Nasim Fazeli ◽  
Adam Nadolny ◽  
Behnaz Safar ali najar ◽  
...  
Keyword(s):  
High Performance ◽  
Energy Performance ◽  
Climatic Conditions ◽  
Office Buildings ◽  
Building Performance ◽  
Visual Comfort ◽  
Different Seasons ◽  
Good Potential ◽  
Shading Devices ◽  
Shading Device

(1) Background: considering multiple, and somehow conflicting, design objectives can potentially make achieving a high-performance design a complex task to perform. For instance, shading devices can dramatically affect the building performance in various ways, such as energy consumption and daylight. This paper introduces a novel procedure for designing shading devices as an integral part of daylightophil architecture for office buildings by considering daylight and energy performance as objectives to be optimal. (2) Methods: to address the topic, a three-step research method was used. Firstly, three different window shades (fixed and dynamic) were modeled, one of which was inspired by traditional Iranian structures, as the main options for evaluation. Secondly, each option was evaluated for energy performance and daylight-related variables in critical days throughout the year in terms of climatic conditions and daylight situations (equinoxes and solstices including 20 March, 21 June, 22 September, and 21 December). Finally, to achieve a reliable result, apart from the results of the comparison of three options, all possible options for fixed and dynamic shades were analyzed through a multi-objective optimization to compare fixed and dynamic options and to find the optimal condition for dynamic options at different times of the day. (3) Results: through different stages of analysis, the findings suggest that, firstly, dynamic shading devices are more efficient than fixed shading devices in terms of energy efficiency, occupants’ visual comfort, and efficient use of daylight (roughly 10%). Moreover, through analyzing dynamic shading devices in different seasons and different times of the year, the optimal form of this shading device was determined. The results indicate that considering proper shading devices can have a significant improvement on achieving high-performance architecture in office buildings. This implies good potential for daylightophil architecture, but would require further studies to be confirmed as a principle for designing office buildings.

scholarly journals Energy and Greenhouse Gas Savings for LEED-Certified U.S. Office Buildings

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 749
Author(s):  
John H. Scofield ◽  
Susannah Brodnitz ◽  
Jakob Cornell ◽  
Tian Liang ◽  
Thomas Scofield
Keyword(s):  
Greenhouse Gas ◽  
Energy Use ◽  
Energy Savings ◽  
Electric Energy ◽  
Building Energy ◽  
Energy Performance ◽  
Office Buildings ◽  
Ghg Emission ◽  
Site Energy ◽  
New Construction

In this work, we present results from the largest study of measured, whole-building energy performance for commercial LEED-certified buildings, using 2016 energy use data that were obtained for 4417 commercial office buildings (114 million m2) from municipal energy benchmarking disclosures for 10 major U.S. cities. The properties included 551 buildings (31 million m2) that we identified as LEED-certified. Annual energy use and greenhouse gas (GHG) emission were compared between LEED and non-LEED offices on a city-by-city basis and in aggregate. In aggregate, LEED offices demonstrated 11% site energy savings but only 7% savings in source energy and GHG emission. LEED offices saved 26% in non-electric energy but demonstrated no significant savings in electric energy. LEED savings in GHG and source energy increased to 10% when compared with newer, non-LEED offices. We also compared the measured energy savings for individual buildings with their projected savings, as determined by LEED points awarded for energy optimization. This analysis uncovered minimal correlation, i.e., an R2 < 1% for New Construction (NC) and Core and Shell (CS), and 8% for Existing Euildings (EB). The total measured site energy savings for LEED-NC and LEED-CS was 11% lower than projected while the total measured source energy savings for LEED-EB was 81% lower than projected. Only LEED offices certified at the gold level demonstrated statistically significant savings in source energy and greenhouse gas emissions as compared with non-LEED offices.

scholarly journals A Fundamental Study on the Development of New Energy Performance Index in Office Buildings

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2064
Author(s):  
Jin-Hee Kim ◽  
Seong-Koo Son ◽  
Gyeong-Seok Choi ◽  
Young-Tag Kim ◽  
Sung-Bum Kim ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Energy Requirement ◽  
Energy Performance ◽  
Office Buildings ◽  
Light Transmittance ◽  
Wall Structure ◽  
Fundamental Study ◽  
Future Studies ◽  
U Value ◽  
The Impact

Recently, there have been significant concerns regarding excessive energy use in office buildings with a large window-to-wall ratio (WWR) because of the curtain wall structure. However, prior research has confirmed that the impact of the window area on energy consumption varies depending on building size. A newly proposed window-to-floor ratio (WFR) correlates better with energy consumption in the building. In this paper, we derived the correlation by analyzing a simulation using EnergyPlus, and the results are as follows. In the case of small buildings, the results of this study showed that the WWR and energy requirement increase proportionally, and the smaller the size is, the higher the energy sensitivity will be. However, results also confirmed that this correlation was not established for buildings approximately 3600 m2 or larger. Nevertheless, from analyzing the correlation between the WFR and the energy requirements, it could be deduced that energy required increased proportionally when the WFR was 0.1 or higher. On the other hand, the correlation between WWR, U-value, solar heat gain coefficient (SHGC), and material property values of windows had little effect on energy when the WWR was 20%, and the highest effect was seen at a WWR of 100%. Further, with an SHGC below 0.3, the energy requirement decreased with an increasing WWR, regardless of U-value. In addition, we confirmed the need for in-depth research on the impact of the windows’ U-value, SHGC, and WWR, and this will be verified through future studies. In future studies on window performance, U-value, SHGC, visible light transmittance (VLT), wall U-value as sensitivity variables, and correlation between WFR and building size will be examined.

Sign in / Sign up

Export Citation Format

Share Document