Reducing the Risk of Natural Ventilation With Flexible Design

Solar Energy ◽  
2006 ◽  
Author(s):  
Lara V. Greden ◽  
Leon R. Glicksman ◽  
Gabriel Lo´pez-Betanzos
Keyword(s):  
Natural Ventilation ◽  
Energy Savings ◽  
Cooling System ◽  
Building Energy ◽  
Design Parameters ◽  
Energy Prices ◽  
Flexible Design ◽  
Local Climate ◽  
Capital Costs ◽  
The Impact

Performance uncertainty is a barrier to implementation of innovative technologies. This research investigates the potential of flexible design — one that enables future change — to improve the economic performance of a naturally ventilated building. The flexible design of the naturally ventilated building enables future installation of a mechanical cooling system by including features such as space for pipes and chillers. The benefits of the flexible design are energy savings, delay of capital costs and capability of mitigating the risk of a failed building (by installing the mechanical cooling system). To evaluate the flexible design, building energy simulation is conducted over a multi-year time period with stochastic outdoor temperature variables. One result is a probability distribution of the time when the maximum allowable indoor temperature under natural ventilation is exceeded, which may be “never.” Probability distributions are also obtained for energy savings and cost savings as compared to a mechanically cooled building. Together, these results allow decision-makers to evaluate the long-term performance risks and opportunities afforded by a flexible implementation strategy for natural ventilation. It is shown that the likelihood of future installation of mechanical cooling is most sensitive to design parameters. The impact of increased climate variability depends on the local climate. The probability of installing the mechanical system also depends on the comfort criteria. The results show that capital costs for cooling equipment are much greater than the present value of 10 years of cooling energy costs. This result motivates consideration of flexible design as opposed to hybrid cooling designs (which have immediate installation of mechanical cooling). Future work will study the impact of uncertain energy prices on investment attractiveness of naturally ventilated buildings. Other applications of the framework presented herein include replacing the building energy model with a model of another climate-dependent system, such as solar photovoltaic arrays.

Modelling the impact of a Sub-Saharan metropolis (Kampala) on the local climate during specific meteorological conditions of a dry season

2021 ◽  
Author(s):  
Oscar Brousse ◽  
Jonas Van de Walle ◽  
Matthias Demuzere ◽  
Alberto Martilli ◽  
Nicole van Lipzig ◽  
...  
Keyword(s):  
Urban Canopy ◽  
Building Energy ◽  
Dry Season ◽  
Meteorological Conditions ◽  
Sub Saharan Africa ◽  
Wave Radiation ◽  
Local Climate ◽  
Local Climate Zones ◽  
Sub Saharan ◽  
The Impact

<p>In order to build resilient cities in face of climate change in Sub-Saharan Africa, much is to be done to understand the impact of rapid and uncontrolled urbanization on the local climate in the region. Recent efforts by Brousse et al. (2019, 2020) demonstrated that using generic urban parameter information  derived out of Local Climate Zones (LCZ ; Stewart and Oke, 2012) maps created through the World Urban Database and Access Portal Tool framework (Ching et al. 2018) may be used to model the impact of Sub-Saharan African cities on their local climate – using the case of Kampala, the capital city of Uganda. These studies showed that despite the characteristic data scarcity on urban typologies that is present in Sub-Saharan Africa, LCZ could be used as a solution for modelling and studying the urban climates in the region.</p><p>Yet these conclusions were only obtained through the use of the bulk-level urban canopy model TERRA_URB, embedded in the COSMO-CLM regional climate model. We therefore test the applicability of a more complex urban canopy models – the Building Effect Parameterization coupled to the Building Energy Model (BEP-BEM) – over the region. To do so, we focus on short periods with specific meteorological conditions during the dry season spanning from December 2017 to February 2018. These are obtained through a k-means clustering over hourly weather measurements given by the automatic weather station located at the Makerere University, in the city-center of Kampala. Wind direction and speed, 2-meter air temperature, incoming short-wave radiation, precipitation, daily temperature range, 2-meter air relative humidity and near-surface pressure are used to depict 5 weather typologies (ie. clusters) during the dry season. We chose to keep only periods with 5 consecutive days of one weather typology, which results in three 5-day periods of distinct typology. We then run the model for these periods and evaluate its outputs against the state-of-the-art simulation by Brousse et al. (2020) as well as in-situ and satellite observations for certain meteorological variables. After that, we show the effect of the recent urbanization on the local climate for each of those three periods and relate it to the variability in urban heat.</p><p>This study is the first to model a tropical African city at 1 km horizontal resolution using the BEP-BEM model embedded in WRF. The latter could have major implications as more complex urban canopy models coupled to building energy models could shed light on the impact of the built environment on the livability of indoor and outdoor environments in these cities. Furthermore, insights could indeed be gained on the contribution of air conditioning heat fluxes to outdoor temperatures and the energetic consumption needed to keep indoor environments at an optimal temperature. Additionally, by resolving the urban environment in three dimensions, BEP-BEM could help increase our understanding of how specific urban planning and architectural adaptation strategies (like green or cool roofs, roof top solar panel, new building materials, urban greening etc.) may increase the citizens’ thermal comfort and reduce negative health impacts under specific weather conditions.</p>

scholarly journals Energy Conservation Potential of Economizer Controls Using Optimal Outdoor Air Fraction Based on Field Study

Energies ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 5038
Author(s):  
Goopyo Hong ◽  
Chul Kim ◽  
Jun Hong
Keyword(s):  
Energy Consumption ◽  
Energy Conservation ◽  
Temperature Control ◽  
Energy Savings ◽  
Cooling System ◽  
Energy Performance ◽  
Outdoor Air ◽  
Humid Climate ◽  
Differential Enthalpy ◽  
The Impact

In commercial buildings, HVAC systems are becoming a primary driver of energy consumption, which already account for 45% of the total building energy consumption. In the previous literature, researchers have studied several energy conservation measures to reduce HVAC system energy consumption. One of the effective ways is an economizer in air-handling units. Therefore, this study quantified the impact of the outdoor air fraction by economizer control type in cooling system loads based on actual air-handling unit operation data in a hospital. The optimal outdoor air fraction and energy performance for economizer control types were calculated and analyzed. The result showed that economizer controls using optimal outdoor air fraction were up to 45% more efficient in cooling loads than existing HVAC operations in the hospital. The energy savings potential was 6–14% of the differential dry-bulb temperature control, 17–27% of the differential enthalpy control, 8–17% of the differential dry-bulb temperature and high-limit differential enthalpy control, and 16–27% of the differential enthalpy and high-limit differential dry-bulb temperature control compared to the no economizer control. The result of this study will contribute to providing a better understanding of economizer controls in the hospital when the building operates in hot-humid climate regions.

Hybrid Cooling for Thermal-Electric Power Generation

2013 ◽  
Author(s):  
John S. Maulbetsch
Keyword(s):  
Cooling System ◽  
Meteorological Data ◽  
Combined Cycle ◽  
Plant Performance ◽  
Design Parameters ◽  
Water Requirements ◽  
Cooling Systems ◽  
Capital Costs ◽  
Hybrid Cooling ◽  
Dry Cooling

Water use by power plant cooling systems has become a critical siting issue for new plants and the object of increasing pressure for modification or retrofit at existing plants. Wet cooling typically costs less and results in more efficient plant performance. Dry cooling, while costing more and imposing heat rate and capacity penalties on the plant, conserves significant amounts of water and eliminates any concerns regarding thermal discharge to or intake losses on local water bodies. Hybrid cooling systems have the potential of combining the advantages of both systems by reducing, although not eliminating, water requirements while incurring performance penalties that are less than those from all-dry systems. The costs, while greater than those for wet cooling, can be less than those for dry. This paper addresses parallel wet/dry systems combining direct dry cooling using a forced-draft air-cooled condenser (ACC) with closed-cycle wet cooling using a surface (shell-and-tube) steam condenser and a mechanical-draft, counterflow wet cooling tower as applied to coal-fired steam plants, gas-fired combined-cycle plants and nuclear plants. A brief summary of criteria used to identify situations where hybrid systems should be considered is given. A methodology for specifying and selecting a hybrid system is described along with the information and data requirements for sizing and estimating the capital costs and water requirements a specified plant at a specified site. The methodology incorporates critical plant and operating parameters into the analysis, such as plant monthly load profile, plant equipment design parameters for equipment related to the cooling system, e.g. steam turbine, condenser, wet or dry cooling system, wastewater treatment system. Site characteristics include a water budget or constraints, e.g. acre feet of water available for cooling on an annual basis as well as any monthly or seasonal “draw rate” constraints and meteorological data. The effect of economic parameters including cost of capital, power, water and chemicals for wastewater treating are reviewed. Finally some examples of selected systems at sites of varying meteorological characteristics are presented.

Analysis of Facade Redesign for Enhanced Satisfaction and Improved Building Performance

2014 ◽  
Vol 490-491 ◽  
pp. 845-853
Author(s):  
Serik Tokbolat ◽  
Sarim Al-Zubaidy
Keyword(s):  
Natural Ventilation ◽  
Well Being ◽  
Building Envelope ◽  
Building Performance ◽  
Energy Prices ◽  
Existing Building ◽  
Low Energy Buildings ◽  
Wind Intensity ◽  
The Impact ◽  
Occupant Satisfaction

The building envelope is known to be an important aspect of design and engineering of ultra-low energy buildings. The facade (building skin) could have the potential to redirect and filter daylight, influence frontal external wind intensity, provide natural ventilation, manage heat transfer, enhance occupant well-being, and create visual and physical connections between the inside and outside. The advances in facade technologies have been triggered in part by higher energy prices, stricter building codes, and higher occupant and owner expectations regarding the quality of the finished construction. This paper provides a comparative assessment of the effect of redesigning an existing building facade and other building improvements. It assesses the impact on external environmental conditions (wind speed and pressure) by employing computational fluid dynamics. The impact of these changes on occupant satisfaction was also gauged. It is hoped that this analysis will provide a framework for assessing benefits of improved facades in other buildings and applications

Assessment of Different Natural Ventilation Strategies for an Educational Building on the Warm-Humid Climate of Guayaquil, Ecuador

2015 ◽  
Author(s):  
R. David Beltrán ◽  
Juan Kastillo ◽  
Isabel Miño-Rodríguez ◽  
Carlos Naranjo-Mendoza ◽  
Carlos Ávila
Keyword(s):  
Energy Consumption ◽  
Natural Ventilation ◽  
Energy Savings ◽  
Main Concern ◽  
Humid Climate ◽  
The Real ◽  
Ventilation Strategies ◽  
Definition Of ◽  
The Impact ◽  
Real State

Natural ventilation has been studied as an effective strategy in order to reduce energy consumption without compromising occupant’s hygrothermal comfort in warm-humid climates. However, the main concern about the current state of art in the use of Building Energy Simulation (BES) as an approach to natural ventilation is the definition of input data which usually do not represent the real state of the buildings in the studied region. Within this context, the main contribution of this research is to propose a methodology through which the real state of buildings can be evaluated. By this analysis, valid input parameters was found to exploit the capabilities of BES and CFD simulations to fulfill the main objective of this study, which is to assess the impact of natural ventilation strategies in the energy consumption of HVAC systems and occupants hygrothermal comfort. Four natural ventilation strategies were evaluated: single sided ventilation, cross ventilation, solar chimney and double façade. The results show that the exclusive use of natural ventilation is ineffective to ensure hygrothermal comfort in a building with high thermal loads in a warm-humid climate like Guayaquil. However, by using a hybrid system (natural ventilation/dehumidification and cooling) cooling energy consumption can be reduced in up to 10.6% without compromising occupant’s hygrothermal comfort. Due to the promising results regarding energy savings, further research will aim to evaluate the impact of other passive strategies in energy consumption.

Airflow Uniformity Through Perforated Tiles in a Raised-Floor Data Center

2005 ◽  
Author(s):  
James W. VanGilder ◽  
Roger R. Schmidt
Keyword(s):  
Data Center ◽  
Cooling System ◽  
Design Parameters ◽  
Airflow Rate ◽  
Simple Estimate ◽  
Cfd Models ◽  
System A ◽  
Data Center Cooling ◽  
Floor Plans ◽  
The Impact

The maximum equipment power density (e.g. in power/rack or power/area) that may be deployed in a typical raised-floor data center is limited by perforated tile airflow. In the design of a data center cooling system, a simple estimate of mean airflow per perforated tile is typically made based on the number of CRAC’s and number of perforated tiles (and possibly a leakage airflow estimate). However, in practice, many perforated tiles may deliver substantially more or less than the mean, resulting in, at best, inefficiencies and, at worst, equipment failure due to inadequate cooling. Consequently, the data center designer needs to estimate the magnitude of variations in perforated tile airflow prior to construction or renovation. In this paper, over 240 CFD models are analyzed to determine the impact of data-center design parameters on perforated tile airflow uniformity. The CFD models are based on actual data center floor plans and the CFD model is verified by comparison to experimental test data. Perforated tile type and the presence of plenum obstructions have the greatest potential influence on airflow uniformity. Floor plan, plenum depth, and airflow leakage rate have modest effect on uniformity and total airflow rate (or average plenum pressure) has virtually no effect. Good uniformity may be realized by using more restrictive (e.g. 25%-open) perforated tiles, minimizing obstructions and leakage airflow, using deeper plenums, and using rectangular floor plans with standard hot aisle/cold aisle arrangements.

scholarly journals Attaining sustainable high-rise office buildings in warm-summer-cold-winter climates: a case study on Frankfurt

2019 ◽  
Vol 14 (4) ◽  
pp. 533-542
Author(s):  
Yuanda Hong ◽  
Wu Deng ◽  
Collins I Ezeh ◽  
Zhen Peng
Keyword(s):  
Energy Savings ◽  
Building Energy ◽  
Energy Performance ◽  
Major Elements ◽  
Office Buildings ◽  
Cold Winter ◽  
Winter Climate ◽  
High Rise ◽  
Warm Summer ◽  
The Impact

Abstract Attaining sustainability in high-rise office buildings necessitates determining the major elements and their associating impacts on the energy performance of this building typology. This study investigates the impact of architectural and engineering features on the energy performance of high-rise office buildings within a warm-summer-cold-winter climate. A rectangular building plan form with a 1:1.44 plan ratio, vertical split core position and central atrium presented the best building performance. The plan form, core position and atrium effect accounted for 59, 30 and 11%, respectively, of an estimated 20.6% building energy savings. Furthermore, exploiting passive strategies founded on the climate and building features as defined by `PassivHaus’ standards further reduced the building energy usage.

A Detached House Simulation Using the International Building Physics Toolbox in Matlab\Simulink

2012 ◽  
Vol 162 ◽  
pp. 567-574
Author(s):  
Vlad Muresan ◽  
Balan Radu ◽  
Donca Radu ◽  
Laura Pacurar
Keyword(s):  
Energy Consumption ◽  
Energy Savings ◽  
Heating System ◽  
Building Energy ◽  
Matlab Toolbox ◽  
Energy Behavior ◽  
Detached House ◽  
Building Physics ◽  
Radiant Floor Heating ◽  
The Impact

Energy savings are an important issue in the context of climate change. The main goal of researchers is to study and develop new methods of improving energy efficiency in household heating. In this paper a Matlab toolbox is presented and explained. The toolbox is developed for researchers and students interested in simulating building energy behavior. A test room is developed and simulated and a radiator model is implemented. Two types of heating are used during the simulation: a radiant floor heating and a panel radiator. A simple on-off control is used for each heating system. The goal of the paper is to study the impact on energy consumption of each heating system used and their impact on energy consumption when the two heating systems are used in different configurations.

scholarly journals Research on the Impact of Wind Angles on the Residential Building Energy Consumption

2014 ◽  
Vol 2014 ◽  
pp. 1-15 ◽  
Author(s):  
Zou Huifen ◽  
Yang Fuhua ◽  
Zhang Qian
Keyword(s):  
Energy Consumption ◽  
Heat Loss ◽  
Indoor Air ◽  
Wind Direction ◽  
Natural Ventilation ◽  
Building Energy ◽  
Simulation Software ◽  
Outdoor Environment ◽  
Building Energy Consumption ◽  
The Impact

Wind angles affect building’s natural ventilation and also energy consumption of the building. In winter, the wind direction in the outdoor environment will affect heat loss of the building, while in summer the change of wind direction and speed in the outdoor environment will affect the building’s ventilation and indoor air circulation. So, making a good deal with the issue of the angle between local buildings and the dominant wind direction can effectively solve the winter and summer ventilation problems. Thereby, it can enhance the comfort of residential person, improve indoor air quality, solve heat gain and heat loss problems in winter and summer in the severely cold and cold regions, and reduce building energy consumption. The simulation software CFD and energy simulation software are used in the paper. South direction of the building is the prototype of the simulation. The angle between the direction of the building and the outdoor environment wind is changed sequentially. Energy consumption under different wind angle conditions is compared with each other. Combined with natural ventilation under various wind angles, the paper gives the best recommended solution of building direction in Shenyang.

scholarly journals Thermal comfort optimization through bioclimatic design in Mediterranean cities

F1000Research ◽  
2021 ◽  
Vol 10 ◽  
pp. 1047
Author(s):  
Nermine Hany ◽  
Hala Alaa
Keyword(s):  
Thermal Comfort ◽  
Natural Ventilation ◽  
Negative Impact ◽  
Residential Buildings ◽  
Technical Information ◽  
Developed Countries ◽  
Positive Contribution ◽  
Local Climate ◽  
Bioclimatic Design ◽  
The Impact

Background: Bioclimatic design is an approach based on local climate which improves thermal qualities and indoor comfort. Buildings follow this process to minimize negative effects on the environment. However, this approach is still not suitable in developed countries. This study aims to investigate Mediterranean local bioclimatic strategies’ impact on thermal comfort efficiency in housing, by examining architectural elements and treatments. Methods: We adopted a descriptive, analytical, and comparative methodology, complemented with a software simulation, within a qualitative and quantitative approach. Investigation and methodological tools were based on technical information including plans, elevations, photos, and documentation. The approach consisted of multiple stages: a literature review interpreting the concept of bioclimatic design, as well as thermal comfort variables and common Mediterranean building features. Moreover, the paper showcases three examples of successful Mediterranean passive houses. Furthermore, the paper presents a case- studyhouse in Alex West, Alexandria, designed in the Mediterranean Revival style. Results: The results showed that the most influencing building features on thermal comfort were the low-pitched roofs and the top chimney, which achieved 12.6% and 5% improvement in the summer and 13% and 6.8% in winter, respectively. The pergola and porch elements barely had an effect when placed on the northern façade. However, on the southern façade, a positive contribution in the summer by 1.4% and 3.4% respectively were reported, but a slight negative impact in winter by 0.5% and 2% respectively. Conclusions:  We examined the impact of common Mediterranean building features , and compared thermal comfort results between case-study houses. Features focusing on passive design for cooling rather than heating, allowing wind flow for maximized natural ventilation, using ventilated pitched roof spaces, using sun shading elements in the proper facades and angles, help passive thermal regulation. The study proposes recommendations for optimizing thermal comfort in residential buildings in Alexandria, Egypt.

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