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The calculation of climatic design conditions in the 2005 ASHRAE Handbook - Fundamentals
Abstract
ASHRAE Research project 1273-RP recalculated and expanded the tables of climatic design conditions in the ASHRAE Handbook - Fundamentals. These tables provide values of dry-bulb, wet-bulb, and dew-point temperature, enthalpy, and wind speed at various frequencies of occurrence over annual and monthly periods and for some of these, mean coincident values of other variables of interest. Compared to the previous edition of the Handbook, the new tables include additional elements and are calculated for a much greater number of stations over a longer period of record. This paper explains the procedure used to compute the design conditions, the data sources used, the techniques employed to screen out erroneous data, and the completeness criteria required by the calculation. It also provides a summary of the stations included in the 2005 Handbook and a brief description of how the new values compare to those published in the 2001 edition. Finally, the paper provides an overview of the capability of the Weather Data Viewer, a companion CD-ROM that gives full access to the frequency information used to compile the tables of climatic design conditions.
... Finally, the performance of buildings' cooling systems in Texas was evaluated based on climatic changes. Therefore, this study aims to answer the following research questions: After evaluating climatic outdoor design conditions in terms of both dry bulb temperature (DBT) and wet bulb temperature (WBT), based on the ASHRAE technical report [26], the first section of the study looks at the demographic trend impact on DBT and WBT in selected cities over thirty years (in each five-year interval). In the second part, the impact of climate change on variations in cooling degree hours (CDH), heating degree hours (HDH), and neutral mode (NM) parameters are evaluated under the influence of the DBT trend. ...
... To evaluate climatic outdoor design conditions, it is necessary to consider annual simple climate design values according to the 2005 ASHRAE Handbook-Fundamentals [26]: ...
... For example, the 0.4% dry-bulb design condition had been calculated by totaling rows in the (dry-bulb, dewpoint) joint frequency matrix, which resulted in indices such as DBT and dew point temperature not being considered. In the new edition [26], however, the frequency vectors were formed by the number of hours (Nbin) within each temperature interval (bin). The present study estimates the frequency vector for a total period of 30 years (from 1990 to 2020) at successive five-year interval periods (six different time frames : 1990-1995, 1995-2000, 2000-2005, 2005- ...
The excessive use of energy in buildings due to increased populations and economic development leads to more greenhouse gas emissions, which affect climate change and global warming. Changes in prevailing outdoor weather conditions significantly affect the energy systems of buildings through increased cooling and decreased heating. In this paper, 30 years of data of dry and wet bulb temperatures (1990–2020) with a time interval of 3 h were considered in order to estimate the climatic outdoor design conditions in the cities of Dallas‒Fort Worth, Houston, and San Antonio in the state of Texas. The results suggest that the dry bulb temperature (DBT) had significantly higher increases in Dallas–Fort Worth (2.37 °C) than the wet bulb temperature (WBT) in Houston (4.1 °C) during the study period. Furthermore, this study analyzed the effects of climate change on cooling degree hours (CDH) and heating degree hours (HDH) and the results suggest the most significant drop in HDH in Dallas–Fort Worth with a maximum CDH fluctuation as compared to other two cities. The effect of climate change on the performance of cooling systems is also investigated in this study via direct evaporative coolers (DECs) and direct‒indirect evaporative coolers (IDEC), which do not perform well in the selected cities. In contrast, absorption system (Abs) and vapor compression (VC) systems show an increase in the number of additional loads. The second part of this study is related to the future projection using the ARIMA model, which suggests that DBT would rise significantly in Houston (from 37.18 °C to 37.56 °C) and Dallas–Fort Worth (39.1 °C to 39.57 °C) while diminishing in San Antonio (from 34.81 °C to 33.95 °C) from 2020 to 2030. In contrast, WBT will experience an upward trend in Houston (from 36.06 °C to 37.71 °C) and Dallas–Fort Worth (from 31.32 °C to 31.38 °C) and a downward trend in San Antonio (from 32.43 °C to 31.97 °C) during 2020–2030. Additionally, the future performance prediction of Abs and VC systems is also performed, which reveals that the amount of additional load required is significantly higher in 2030 compared to 2020 and is more prominent in Houston. Conversely, amount of additional load required for cooling systems in San Antonio shows a decreasing trend in 2030.
... This house is located in a cold and humid environment of Newfoundland in Zone 6. According to the ASHRAE standard [11], and the house built on the guidelines of PHIUS+2015. The red colour envelope is the main living area of the Passive House, and the gray colour envelop is the garage consist of a smaller portion of the house, as shown in Figure 1. ...
... So, weather data from the EnergyPlus website has been downloaded. Figure 6 shows the heating degree day data of Canada, according to ASHRAE guideline, and the site with red marker has shown which comes under zone six [11]. The site has a lot of variation in temperature throughout the year, and the ASHRAE climate zone ranges from 2222-2777 heating degree day (HDD) when data from Figure 6 is converted from Fahrenheit HDD to Celsius HDD. ...
... All these variables can be more effectively stimulated with dynamic simulation tools where the properties of each device installed can be selected along with sudden changes of climate variables to achieve more accurate results. heating degree day (HDD) for Canada [11]. ...
This paper present the building performance of a house in Newfoundland, Canada. This house is built under the guidelines of the Passive House Institute United States (PHIUS+2015) standards. This is an important step took towards sustainable living in Newfoundland and Canada in general. Detailed energy consumption modelling of the house has been performed along with the steps involved in the simulation process of Passive House planning and renewable energy system sizing. A significant part of the study presents the majority of the construction details of the house and the components involved. In this study, we present actual energy consumption data acquired from the house and the simulation performed in both pre-construction and post-construction phases. Additionally, steps followed during the planning and construction phase have been discussed in detail, and both static and dynamic energy modelling has been compared. Moreover, a cost comparison has been performed to calculate all the additional costs spent on the resources to build the house according to the Passive House (PHIUS+2015) standards; the analysis indicated a cost of 12% extra when compared with the house built under local regulations. Finally, a renewable energy system is proposed for the house to meet the electricity needs of the house.
... The reporting stations in the HOF'09 dataset are widely distributed and representative of major climatic zones [18]; hence, suitable for a global analysis of the relationship between annual mean temperature and degreedays. Further details on the dataset and underlying methodology are discussed in [2,19,20]. ...
... Given the regression coefficients for HDD 18.3 and CDD 10 in Tables 2 and 4, respectively, the relationship between degree-days and the independent variables in model #6 can be described as Eqs. (18) and (19). ...
... Errors in Eqs. (18) and (19) tend to occur at lower tail ends of HDD 18.3 and CDD 10 respectively. This is primarily because of points of inflection in 4th order curves in Fig. 2. Closer inspection of the original data reveals that degree-days around the inflection points are very low -either zero or very close to zero. ...
Degree-days are a versatile climatic indicator and used for many applications in the design and operation of en- ergy efficient buildings – from the estimation of energy consumption and carbon emissions due to space heating and cooling to the energy and environmental monitoring of buildings. This research is aimed at developing an equation for calculating degree-days from low-resolution temperature data by exploring the relationship between degree-days and annual mean temperature of 5511 locations around the world, using multiple non-linear regres- sion. Results suggest a very strong relationship between annual mean temperature and degree-days. Incorporating standarddeviation(SD)ofmonthlymeantemperatureandlatitudeincreasestheaccuracyofprediction(R2 >.99), demonstrating the strength of the location-agnostic relationship in predicting degree-days from two temperature parameters: annual mean and SD of monthly mean. Research findings can be used to calculate degree-days of loca- tions, for which daily temperature data may not be available. The equation can also be used to calculate degree-days from low-resolution global circulation model (GCM) projections of increasing temperature, for investigating the im- pact of climate change on building heating and cooling energy demand at global scale without the need to create synthetic weather series through morphing or downscaling.
... or sector regulations: the EPW environmental data refers to Borgo Panigale (one of Bologna s districts); the occupancy was evaluated at 28.3 m 2 /person (in line with the calculated data from the Cataloug Matrix); the domestic hot water consumption was considered as 100 L/m 2 a [63]; lighting was determined as 5 W/m 2 based on studies from literature studies [64] and Honeybee; air exchange rates were determined according to the values indicated by the UNI TS 11300-1 regulation [65], 0.3 h −1 for air exchange rate and 0.5 h −1 for older buildings; heating setpoints, cooling setpoints, appliances, and other user schedules refer to the appendices of the UNI EN 16798-1:2019 regulation [63] and the ASHRAE Handbook of Fundamentals 2005 [66]. ...
... This tool enables dynamic simulations of natural lighting and energy consumption using the EnergyPlus/OpenStudio simulation engine. To consider the highly variable behaviour of residential users [62], a set of schedules has been used, some defined by the authors, others derived from literature data or sector regulations: the EPW environmental data refers to Borgo Panigale (one of Bologna's districts); the occupancy was evaluated at 28.3 m 2 /person (in line with the calculated data from the Cataloug Matrix); the domestic hot water consumption was considered as 100 L/m 2 a [63]; lighting was determined as 5 W/m 2 based on studies from literature studies [64] and Honeybee; air exchange rates were determined according to the values indicated by the UNI TS 11300-1 regulation [65], 0.3 h −1 for air exchange rate and 0.5 h −1 for older buildings; heating setpoints, cooling setpoints, appliances, and other user schedules refer to the appendices of the UNI EN 16798-1:2019 regulation [63] and the ASHRAE Handbook of Fundamentals 2005 [66]. ...
The Italian residential building stock consists of 12.2 million buildings, with 7.2 constructed post-World War II during the economic boom. These structures were designed without specific regulations for seismic safety, fire resistance, and energy efficiency, and today lies the current state of strong obsolescence. Therefore, energy refurbishment may not always be the best cost/benefit solution due to these intrinsic issues. Consequently, the transition to construction systems based on circular economy principles brings new opportunities and becomes key to proposing replacement interventions for this heritage. This paper presents a comparative GIS-based bottom-up approach to evaluate the lifecycle impact of residential building blocks, encompassing energy, environmental, and economic aspects. Two tools are introduced: one for measuring energy consumption and the other for quantifying the quantities of materials stored in buildings. This methodology permits comparing the new circular buildings and different refurbishment scenarios to identify the most suitable solution from an environmental impact and financial point of view. The application of a case study, a residential urban block in Bologna, built in 1945–1965, highlights how the demolition and reconstruction scenario based on circular economy principles presents the lowest environmental impacts and is economically competitive compared to standard deep renovation techniques.
... MATLAB code is developed for the solar intensity on tilted surfaces using equations reported in (Thevenard and Humphries, 2005) to determine the ideal yearly solar collector tilting angle that provides the maximum yearly solar radiation collected on the collector at a certain location (Tanta City), and it was found to be 25 • with the horizontal as shown in Fig. 10. The collector tilting angle of 25 • is taken into account in calculations for solar air and water heaters. ...
... Liquid condensed film heat transfer coefficient for plain tub. All properties of the liquid are to be evaluated at the film temperature:(Thevenard and Humphries, 2005) Dh d t,o,co * N t,co * ( T a,sat,Dh − T t,o,co )Coefficient of convective heat transfer in an air flow around tubes(Cengel and Heat, 2003)h a,Dh = C 2 C 1 Pr 0.31 (Re d,max ) m Where C 2 = 0.95 is the correction factor for N t,o,co < 20 Re d,max = ρ a,Dh u a,max d t,o,co μ a,Dh u a,max =ṁ Diffusivity coefficient of vapor in the air [41] h a,Dh = Km a,Dh C p,a,Dh Le 2/3 h a,Dh ≅ Km a,Dh C p,a,Dh Km a,Dh = h a,Dh C p,a,Dh Convective heat transfer coefficient through a water flowing inside the tubes (Cengel and Heat, 2003) For > >> Re d,sw < 2300 h sw,Dh = 1.86 For > >> 2300 ≤ Re d,sw ≤ 10 4For > >> Re d,sw > 10 4 ...
This research describes a hybrid solar desalination system that includes a humidification-dehumidification unit as well as a solar still unit. The current system is being studied numerically. A one-dimensional model of the important heat and mass exchanges, as well as the flow field, was built using the finite difference method. Freshwater productivity is calculated under various operating and weather conditions. The model has been modified to investigate the steady-state behavior of the system components. Four major parameters that have a significant impact on system water production are investigated: the feed flow rate of cooling water through the dehumidifier unit, the airflow rate, and the number and height of packing columns. According to the results, the proposed hybrid desalination system provides appropriate operational compatibility between HDH technology and solar energy. The system can provide a daily production of up to 35 liters per day. Increasing the number of packing columns results in a higher increase in fresh water productivity than increasing the height of the packing columns. The optimal air flow rate at a constant saline-water flow rate is obtained. For high airflow rates, the packing column height doesn't significantly affect the daily water production. System performance is investigated by four main parameters: gained output ratio (GOR), humidifier efficiency, exergy efficiency, and system efficiency. The system efficiency reached about 65% and the GOR reached 3.1. The humidifier’s efficiency varied between 50% and 75%. The maximum exergy efficiency reached about 5.2%.
... The four rules that are to be fulfilled for a day to be considered valid are: Rule A: Every climatic parameter has to be valid in at least 18 h during the day. This has to be satisfied in order to have consistent data to be used in the computation and avoid the presence of too many gaps to be filled with interpolation in the following steps [23]; ...
... This condition is necessary because, if interpolation of values is to be taken in the first/last day, a valid data may be required in the first/last hour to compute the interpolated values; Rule C: For every climatic parameter, a maximum of 6 consecutive hours of invalid data is acceptable across two contiguous days. This limitation aims to avoid the problem of interpolating data across too long time intervals as, for example, near stocks of 5 + 5 h of invalid values [23]; ...
Consistent climate data and reliable sizing methods are fundamental for designing Technical Building Systems. This paper addresses both these aspects with reference to the Italian context analyzing 108 different locations. Regarding the climate data, a quality analysis through the application of rules and filters was performed on the locations. The results showed good data quality, with most sites having high percentages of usable material, although highlighting recursive criticalities in the detection of humidity and wind speed parameters. Regarding the sizing methods, a sensitivity analysis was carried on for the European standard EN ISO 15927-2 to evaluate its performances in selecting the Cooling Design Days in the 108 locations. The analysis highlighted great differences in terms of chosen Design Days when using different climatic parameters, showing at the same time a negligible influence of the wind speed on the selection process. Furthermore, a sizing process for a test building applied to the 108 locations was carried on by using the Cooling Design Days. The results highlighted that the Design Days obtained through the EN ISO method often give counterintuitive sizing outputs, even obtaining higher required powers for lower risk levels, the opposite of how it should be. This implies that a designer should be very careful in evaluating which parameters to use in the Design Day selection and if the output sizing powers obtained through them are reliable for its particular sizing process.
... The reporting stations in the HOF'09 dataset are widely distributed and representative of major climatic zones [18]; hence, suitable for a global analysis of the relationship between annual mean temperature and degree-days. Further details on the dataset and underlying methodology are discussed in [2, 19, 20]. ASHRAE publishes heating and cooling degree-days for two base temperatures: 18.3°C (65°F) and 10°C (50°F) respectively, as they are the most commonly used bases for building energy applications. ...
... Given the regression coefficients for HDD 18.3 and CDD 10 in Tables 2 and 4 respectively, the relationship between degree-days and the independent variables in model #6 can be described as Equations 18 and 19.19) where, HDD 18.3 is annual heating degree-days at 18.3°C (°C-day), CDD 10 is annual cooling degree-days at 10°C (°C-day), T is annual mean temperature (°C), S m is standard deviation of monthly mean temperatures (°C) and L is the latitude of the location in decimal degree (°) where north latitudes are positive and south latitudes are negative. Errors in Equations 18 and 19 tend to occur at lower tail ends of HDD 18.3 and CDD 10 respectively. ...
... The conservation equations for heat and mass are written for each At the beginning, the input parameters were equal to the data taken from that measured by [166] on that day in 2020; spring 21/3, summer A MATLAB code is developed for the solar intensity on tilted surfaces using equations reported in [167] to determine the ideal yearly solar collector tilting angle that provides the maximum yearly solar radiation collected on the collector at a certain location (Tanta City), and it was found to be 25° from the horizontal that is taken into calculations for solar air and water heaters (see APPENDIX (A)). ...
A proposed hybrid desalination system is presented that combines a humidifier-dehumidifier with a solar distiller. The system is theoretically analyzed using the differential volume method, a one-dimensional theoretical model of heat and mass transfers and flow field has been developed. In the present study, the system components have been investigated under steady-state conditions. Four influential desalination-process parameters are investigated: saline water flow rate, airflow rate, and number and height of packing column. The proposed hybrid desalination system can supply up to 35 liter/day. Increasing the number of packing columns outperformed increasing the height in terms of fresh water productivity. Optimal air flow rate at constant saline-water flow rate was found. System performance is evaluated based on Gain Output Ratio, GOR, humidifier efficiency, exergy efficiency, and system efficiency. Gained Output Ratio, GOR, reached 3.1, average system efficiency achieved 36 %, humidifier efficiency ranges 50-75% and exergy efficiency reached 5.2%.
Theoretical investigation for different hybrid-solar desalination system configurations have been conducted. The main comparative parameters that have been studied are water production cost, water productivity, system efficiency, gain output ratio and exergy efficiency. Five configurations have been studied, including three hybrid-layout configurations that comprise air humidification-dehumidification, and solar distiller units, in addition to two distinct standalone layout configurations. The hybrid system, HDH–SD, without solar water heater proved to be the most cost-effective
iii
configuration, with daily water production attaining about 30 liters/day in August.
Experimental work was performed under environmental conditions in September 2021. According to testing and operating parameters, the system highest productivity was 6.7 liter/m2 per day. System performance was tested and represented by system efficiency, humidifier efficiency, and gain output ratio (GOR). The average system efficiency, humidifier efficiency, maximum gain output ratio, and exergy efficiency reached 33 %, 93 %, 1.65, and 7.2 %, respectively. There is good agreement between the theoretical model and experimental work.
The present study includes the development of an exergoeconomic model for the system. Exergy-based loss rate, exergy production factor, exergoeconomic parameters, exergy efficiency and water cost are the main estimated parameters. The exergy loss rate in summer is higher than in fall and spring by about 33% and higher than in winter by about 60%. The exergoeconomic parameter decreases with an increase in interest rate. However, the increase in interest rate causes an increase in water cost. For lifetime 30 years and interest rate equal 2% the lowest water cost is about 1.3 $/m3, but exergoeconomic parameter is the highest.
... As the interface between the heat exchanger tube and the surrounding soil, the choice of backfill material has a significant impact on the efficiency of the heat exchanger. Referring to specifications by ASHRAE [33], Table 3 shows the thermal properties of different backfill materials commonly used in projects. Fig 6 shows that the total heat exchange varies significantly with different backfill materials. ...
Geothermal energy is increasingly employed across diverse applications, with bridge deck snow melting emerging as a notable utilization scenario. In Jinan city, China, a project is underway to utilize ground source heat pumps (GSHPS) for heating bridges. However, essential operational parameters, including fluid medium, temperature, and heat exchange details, are currently lacking. This study addresses the thermal design challenges associated with ground heat exchangers (GHE) for bridge heating through a combination of numerical modeling and field experiments. Utilizing software Fluent, a refined three-dimensional multi-condition heat transfer numerical analysis was carried out. Field tests based on actual operating conditions were also conducted and the design parameters were verified. The results indicate that an inlet temperature of 5°C and an aqueous solution of ethylene glycol with a mass concentration of 35% as the heat exchange medium are suitable for the GSHPS in Jinan; Moreover, the influence of backfill material and operation time on the heat transfer efficiency was revealed and the suitable material with 10% bentonite and 90% SiO2 was suggested; Finally, based on the influence of the pipe spacing on the heating characteristics of bridge deck, the transition spacing of 0.2 m is given for the temperature response of the bridge deck. This comprehensive study contributes valuable insights through simulation and experimental analysis of the thermal environment variation, aiming to advance the development of GSHPS for bridge deck heating in Jinan, China.
... Eqs. (7) to (13) precisely depict the PMV and PPD calculations, drawing from established literature[5,33,34]. Additionally,Table 4encapsulates a comprehensive compilation of all variables and corresponding values utilized in computing PMV and PPD during both the summer and winter seasons, enriching the analytical context. is the metabolic rate, 46 to 232 / 2 (0.8 met to4 met) W: is the external work / 2 , assumed to be 0 for most applications : is the thermal resistance of clothing, 0 to 0.310 2 . ...
This study thoroughly investigates thermal comfort conditions within an indoor swimming pool in a desert climate resembling the climatic conditions of regions like Qatar, known for its scorching summers and mild winters. The research focuses on a 17.6 m x 11.7 m indoor swimming pool, assessing its response to extreme outdoor conditions: 43.3 ℃ dry-bulb temperature and 33.3 ℃ wet bulb temperature for summer, and 17 ℃ dry-bulb temperature and 10.6 ℃ wet bulb temperature for winter. Design considerations maintain indoor temperatures in the range of 24 to 29 ℃ year-round, aligning with ASHRAE Handbook recommendations for indoor swimming pools. The study encompasses a comprehensive analysis, including calculation of pool evaporation rates and resulting latent heat load gain. Hourly Analysis Program (HAP 4.9), a specialized cooling load calculation program, was employed to determine the essential thermal load required to maintain optimum indoor conditions. Computational Fluid Dynamics (CFD) simulations, employing ANSYS Fluent 19.2 and incorporating standard turbulence and moisture content models following a meticulous grid independence study, were conducted. The results highlight distinct average indoor conditions for both summer and winter, encompassing parameters such as air temperature, air velocity, and relative humidity. The research outcomes, assessed using Predicted Mean Vote (PMV) and Predicted Percentage of Dissatisfied (PPD), indicate comfort in summer and slight warmth in winter, serving as a valuable reference for future research on desert pool and greenhouse designs, ultimately enhancing indoor environmental quality.
... Heating, ventilation, and air conditioning (HVAC) [3] is the technology of environmental relaxation [4]. For the first time, it was found by American engineer Willis Carrier. ...
The purpose of this paper is to explore the behavior of Sutterby nanofluid passed a sloping sheet with a tendency to fluctuate thermal conductivity, radiation and a magnetic field. In a solar parabolic trough collector (PTC) for solar cooling and hydrogen generation, a nanofluid is employed as the running fluid. The Koo-Kleinstreuer-Li (KKL) model is used to calculate effective thermal conductivity and viscosity. The advance results are differentiate with the Lobatto 111A method which strengthens the integration reliability of the current liquid system. Copper oxide-engine oil (CuO-EO) is taken into consideration to address the performance analysis of the current study. The skin coefficient and the local Nusselt number are expressed numerically in the form of a table, whereas other dominant competent parameters on the speed and temperature profiles are discussed numerically and graphically. The radiation parameter slows the rate of heat transfer while increasing the velocity gradient. To test the effect on many device performance parameters, nanoparticle absorption also varies with the growth of Reynolds and Brinkman numbers, entropy creates growth. The thermodynamic action of copper oxide-engine oil (CuO-EO) nanofluid is more noticeable than engine oil (EO) nanofluid oil under similar conditions. CuO-based EO nanofluid system had the best heat transmission efficiency and hydrogen generation. The thermal effectiveness of CuO-EO over EO is characterized by a minimum of 2.89% and a magnitude of 14.79%. Written theory simulations may be more effective in developing solar thermal energy systems.
... Among the possible variables analyzed, the need to evaluate the mood of teachers with temperatures is stressed because there is no solid scientific basis [41]. For this, it is essential to develop studies that include multisensory approaches and consider variables such as the amount of C02, lighting, noise and air speed [29,30]. ...
This study investigates how temperature, inside and outside the classroom, influence teachers’ mood and mental fatigue as well as the perceived students’ behavior. Two daily random measurements of the temperature inside various classrooms were taken for 7 months. Mood, mental fatigue, and perception of students’ behavior were evaluated for the teachers. Daily external temperature data were obtained from the State Agency of Meteorology. Results showed that indoor temperature, indoor humidity, and the difference between outdoor/indoor temperature significantly explain a worse perception of mood of the teachers and a worse perception of students’ behavior that influences perception of students’ behavior.
... The evaluation of the annual dry-bulb design criteria is based on a comparison of the annual 99.6%, 99.0%, 2.0%, 1.0%, and 0.4% dry-bulb temperatures estimated from the MERRA-based cumulative distribution functions (CDFs) developed from the MERRA hourly temperatures and the corresponding annual 99.6%, 99.0%, 2.0%, 1.0%, and 0.4% dry-bulb temperatures taken from the WDV-4, where the site specific values from the WDV-4 are based upon surface station hourly observations. The methodology for determining the annual CDFs and subsequently the 99.6%, 99.0%, 2.0%, 1.0%, and 0.4% dry-bulb temperatures is described in Thevenard and Humphries (2005) and by Thevenard (2009). Evaluation of the MERRA-based annual design conditions focused on the CONUS study-region, and was accomplished by first acquiring the MERRA hourly temperature for the 6480 0.5°grid boxes contained within the CONUS study-region. ...
ASHRAE Technical Committee 4.2, Climatic Information, publishes a quadrennial update of climatic design information in Chapter 14 of the ASHRAE Handbook - Fundamentals(ASHRAE 2009a). The design information for 5564 locations around the world is based upon hourly values of dry-bulb temperature, wet-bulb temperature, dew-point temperature, wind speed and direction, surface pressure, and solar radiation. The 2009 design conditions provided a significant enhancement over the 2005 design conditions with respect to the global coverage - 5564 locations in 2009 versus 4422 locations in 2005. The ASHRAE design conditions, based on meteorological data, are calculated using hourly surface data from stations having a minimum of 8 years of observations, but more stations typically span 25 years of observations; although frequently the time series are discontinuous. The ASHRAE solar-related design conditions are based on model-derived solar radiation. A potential source for both global and time contiguous meteorological and solar data is NASA’s POWER(Prediction of Worldwide Energy Resource) web portal (NASA2013a). This includes the recently available meteorological data based on an improved reanalysis model - Modern Era Retrospective-analysis for Research and Applications(MERRA). MERRA yields global, hourly surface meteorological parameters for the years 1981 to present. An initial evaluation of the MERRA daily maximum, minimum, and averaged temperatures indicates accuracies sufficient to warrant their use to supplement existing surface observations. In this paper, we present an evaluation of the accuracy of the MERRA daily temperatures, followed by an assessment of the applicability of the MERRA hourly temperatures in the development of annual dry-bulb climate design criteria and annual heating and cooling degree-days over the continental United States.
... The 2005 edition increased the number of world sites to 4422, and introduced many improvements, particularly in the number of temperature-and humidity-related parameters, and their statistical interactions. These improvements reflected the results from an exhaustive study (Thevenard and Humphries, 2005). However, the SHG calculation method remained unchanged, despite the known problems and limitations of the ASHRAE radiation model, which are discussed in Section 2. Because of the need for a more accurate and universal radiation model, another study has recently been conducted to improve the incident radiation modeling and SHG calculation methodology, while further (i) expanding the number of world sites to over 5400 worldwide; (ii) providing still more climatological indices and monthly statistics. ...
This paper establishes the formulation of a new clear-sky solar radiation model appropriate for algorithms calculating cooling loads in buildings. The aim is to replace the ASHRAE clear-sky model of 1967, whose limitations are well known and are reviewed. The new model is derived in two steps. The first step consists of obtaining a reference irradiance dataset from the REST2 model, which uses a high-performance, validated, two-band clear-sky algorithm. REST2 requires detailed inputs about atmospheric conditions such as aerosols, water vapor, ozone, and ground albedo. The development of global atmospheric datasets used as inputs to REST2 is reviewed. For the most part, these datasets are derived from space observations to guarantee universality and accuracy. In the case of aerosols, point-source terrestrial measurements were also used as ground truthing of the satellite data. The second step of the model consists of fits derived from a REST2-based reference irradiance dataset. These fits enable the derivation of compact, but relatively accurate expressions, for beam and diffuse clear-sky irradiance. The fitted expressions require the tabulation of only two pseudo-optical depths for each month of the year. The resulting model, and its tabulated data, are expected to be incorporated in the 2009 edition of the ASHRAE Handbook of Fundamentals.
Thermal comfort in housing is vital for well-being. Despite hot and humid regions experiencing shorter cold periods compared to heatwaves, vulnerable populations are susceptible to threats from cold snaps. However, existing research overlooks undercooling risks in hot regions during winter. This study examines self-built houses in densely populated, hot and humid areas, mainly occupied by elderly residents. We conducted an on-site measurement recording hourly indoor air temperature, humidity, and black globe temperature during wintertime. Two thermal comfort metrics (aPMV and adaptive regression model) and two resilience metrics (SET degree-hour, Hours of Safety) were used to quantify thermal conditions during cold periods under current and future climate conditions. The results show that undercooling hours in recent years exceed 90 % of wintertime using aPMV index and adaptive regression models. Under future climate scenarios (Representative Concentration Pathways), undercooling hours only decrease by 10 %–25 % from 2020 to 2100 across all metrics. Extreme cold events in 2018 saw SET degree-hours double the thermal resilience threshold, while they pose health risks to the elderly for up to 21 days according to the HOS metrics. This study aims to identify the importance of addressing winter thermal comfort in hot and humid regions and to assess the risk posed by cold snaps to vulnerable populations. By quantifying these risks, the study contributes to better decision-making regarding hot-humid region housing thermal retrofit strategies for architects, engineers, and other stakeholders.
In order to understand the thermal process of passive solar dormitories in highland areas, this paper establishes a heat transfer model for passive solar student dormitories and analyses the effects of convective heat transfer coefficient and thermal conductivity of their envelope surfaces on the heat storage, and then analyses the effects on indoor air temperature. The results show that increasing the convective heat transfer coefficient of the floor surface and the thermal conductivity of the floor can both increase the indoor air temperature. Once the thermal conductivity has been increased to 1.5 W/(m2·K), further improvements are no longer noticeable in terms of temperature increase. Increasing the convective heat transfer coefficient of the floor surface and the thermal conductivity of the floor both enhance the heat storage of the floor. When the thermal conductivity is less than 1.5 W/(m2·K), increasing the thermal conductivity has a greater impact on the heat storage of the floor, while increasing the convective heat transfer coefficient has a less obvious impact on the heat storage of the floor. This paper is a guide to optimizing the energy efficiency of passive solar buildings of the same type.
The active chilled beam system has been popularly used in office and meeting rooms. There are very few studies of their terminal configuration on the thermal comfort and ventilation performance of systems with different heat gains. A comparative experimental study was implemented in mock-up office and meeting rooms to provide a comprehensive evaluation of the airflow patterns, air distribution, ventilation effectiveness, and local thermal comfort of the 4-way system. Four different terminal layouts with two types of the chilled beams (600 unit and 1200 unit sized 0.6m × 0.6m and 1.2m × 0.6m, respectively) were tested at three heat gain levels: low (46W/m²) and medium (66W/m²) heat gains in the office room, and high (92W/m²) heat gain in the meeting room. The results revealed that the terminal layouts and heat gain levels had significant effects on air distribution and local thermal comfort. The increased heat gains generated lower heat removal effectiveness, worse indoor thermal uniformity, and increased risk of draught. Generally, the 1200-unit system performed better than that with 600 units for heat removal effectiveness and contaminant removal effectiveness. In terms of local thermal comfort, the 600-unit system generally provided higher performance than that with the 1200-unit system. The practical recommendations for the system design and operation stages are provided based on the operating range of the 4-way systems under variable terminal layouts and heat gain conditions.
Understanding the climate and location aspects are usually the first step in energy applications - from buildings to renewable energy. With so many of the renewable energy sources being significantly dependent on weather, it is essential that the temporal and geospatial variability and distribution of climatic design parameters are investigated for effective planning and operation. ASHRAE-HOF is the most widely used climatic design conditions database for building energy and HVAC professionals, but gaps exist in the literature on the geospatial and temporal distributions of the HOF dataset. This research explored geospatial distributions of key HOF (2009) climatic parameters: temperature (dry-bulb, wet-bulb, dew-point and mean) and degree-days at various temporal scales. Identified spatial variability illustrate the effects of latitude, elevation, landuse and nearest coastline. Observed trends agree with conventional wisdom; however, sparse coverage in populated areas such as Africa and Asia diminish the versatility of the database. Variations in temperature exist, even between closely spaced sites -emphasizing the need to use location-specific data for enhancing the accuracy of the weather-related analysis. Moreover, latitudinal similarities in the distribution offer potential in identifying candidate locations for reciprocal transfer of knowledge on environmental design and operation.
Calculation of climatic design conditions and cooling and heating degree days using data from different decades for 1274 stations worldwide reveals long-term trends. Over the last three decades, climatic design conditions have increased at an average rate of 0.76°C/decade (137°F/decade) for the 99.6% heating dry bulb temperature, 0.38°C/decade (0.68°F/decade) for the 0.4% cooling design temperature, and 0.28°C/decade (0.50°F/decade) for the 0.4% dehumidification dew point temperature. Annual heating degree-days have decreased on average by 118°C-day/decade (212°F-day/decade) while annual cooling degree days have increased by 68°C-day/decade (122°F-day/decade). These changes are indicative of a warming of the climate experienced by the monitoring stations. However, the magnitude of that warming indicates that it is probably less related to global warming than to the urban heat island effect; it is likely an indication of the built environment encroaching on locations where meteorological stations are situated, particularly airports. The paper also studies the appropriate period of record to use for the calculation of climatic design conditions and degree-days. The use of a 30-year period is recommended; the use of shorter periods of record encompassing only recent years, in order to better capture climatic trends, results in an added uncertainty that is greater than the observed climate trends themselves.
ASHRAE Research Project RP-1613 prepared an update of the climatic design conditions for the "Climatic Design Information" chapter of ASHRAE Handbook - Fundamentals and for ANSI/ASHRAE Standard 169, Weather Data for Building Design Standards. This update resulted in an increase of the number of stations to 6443 (a 16% increase compared to 2009) and the inclusion of precipitation data used in particular to determine climate zones in energy standard ANSI/ASHRAE/IES Standard 90.1. A more recent period of record (1986-2010 for most stations) was used to incorporate changes in the climate. Compared to the previous edition, climatic design temperatures are generally slightly higher, cooling degree are slightly higher, and heating degree-days are lower, which is indicative of a general warming of the climate. In addition, RP-1613 prepared an update of the Weather Data Viewer, a stand-alone product used by engineers to access the full single- and joint-frequency distributions of all the climatic design parameters listed in ASHRAE Handbook Fundamentals, as well as additional parameters, such as temperature bin data and wind roses. Part two of the paper, "Revising ASHRAE Climatic Data for Design and Standards - Part II: Clear-Sky Solar Radiation Model," provides a detailed description of the changes made to the clear-sky solar radiation model.
This paper summarizes the preparation of climatic design conditions for the 2009 ASHRAE Handbook - Fundamentals. The project (a) redefined new percentiles of monthly dry bulb and wet bulb temperatures to represent 'less extreme ' conditions than those used in the past, (b) added new monthly dry bulb and wet bulb coincident temperature ranges which can be used for the derivation of daily temperature profiles, (c) calculated heating and cooling degree-days base 50°F (10°C) and 65°F (18.3°C), in support of various standards including ASHRAE Std. 90.1-2004, and added parameters to accurately evaluate degree-days to any other base, and (d) developed a new clear sky solar irradiance model, to overcome the known limitations of the existing ASHRAE clear sky model and extend its applicability to the whole world. The most recent 25 years of climatic data (1982-2006 at the time of processing) were used to calculate the revised tables of climatic design conditions. This provides a balance between accounting for long-term trends and the sampling variation owing to year-to-year variation. Processing led to the calculation of climatic design conditions for a total of 5,564 locations worldwide.
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