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Updating the ASHRAE climatic data for design and standards
Abstract
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.
... Currently, there are two main design-day construction methods: The first is based on a theoretical mathematical model (Antonanzas-Torres, Urraca, Polo, Perpiñán-Lamigueiro, & Escobar, 2019). The second is based on a standardized profile (Thevenard & Gueymard, 2010). These two methods help with design-day construction in the absence of a historical meteorological record in some regions and make the process of design-day generation simple and convenient. ...
... These two methods help with design-day construction in the absence of a historical meteorological record in some regions and make the process of design-day generation simple and convenient. However, both the theoretical mathematical model and the standardized profile only reflect the diurnal variation characteristics of one meteorological element (Thevenard & Gueymard, 2010) while ignoring the correlation between the diurnal variation trends of each meteorological element. There is a certain coupling relationship between the diurnal variation characteristics of the outdoor meteorological parameters. ...
Design days are the fundamental parameters for design cooling load calculations. At present, the coincidence and coupling relationship of meteorological elements are ignored by the design-day selection methods provided in the current standards, which results in conservative and unreasonable designs. This research proposes a method of selecting design days for design cooling load calculation that considers the coincidence and correlation of meteorological elements. First, a joint distribution function is constructed; on this basis, the coincident near-extreme meteorological parameters are selected. Then three meteorological elements from a 30-year meteorological record are integrated into one single normalization parameter. Finally, a design day reflective of the variation trend of near-extreme climate conditions is selected from the meteorological record. This paper uses Tianjin in China as an example to generate the research design day. It was found that the outdoor non-guaranteed rate of the research design day is roughly consistent with the corresponding indoor thermal environment risk level. Compared with the standard Chinese design day, the peak values of the research design day are reduced effectively, and the gap between the indoor thermal environment risk level and the outdoor non-guaranteed rate is narrowed.
... They form the link between solar radiation and other local conditions such as elevation and aerosols. The ASHRAE research project RP-1453 (Thevenard 2009) was used to determine the average values of b and d . The values were recorded for the 21st day of every month for all locations in the tables of climatic design conditions. ...
... The values were recorded for the 21st day of every month for all locations in the tables of climatic design conditions. For the other days of the year, average values of b and d can be found by interpolation [10]. ...
This study presents statistical relationships between various meteorological elements in Seoul city. It also discusses the vitality of the obtained relationship on the modelling of building energy consumption. The data utilized in statistical evaluations was obtained from the archives of the Korean Meteorological Agency (KMA) for a period of four years. Another set of data was derived from state-of-the-art equations. The used elements aside from aerosols are used for analysis in building energy simulations. For each weather element in the study, frequency and a monthly average are presented. Furthermore, statistical correlations are presented: solar radiation and temperature, solar radiation and sky cover, and solar radiation and aerosol optical depth (AOD). The results indicate that the common assumption of a direct relationship between temperature and solar radiation is rather incorrect. In addition, whereas high solar altitudes are usually associated with high levels of solar radiation, the obtained results indicate a relatively weak relationship between the two variables ( R2 = 0.463). The obtained results are proof that the effect of meteorological elements on, say, a building is not a single direct effect from a single variable but rather a combination of relationships between variables, which then produce a single effect.
... Therefore, the authors employ a " clear-sky " model [5], to provide an estimate of solar intensity which ignores the impacts of cloud cover; this conservative approach allows the analysis to investigate all possible solar positions and predicts an upper limit on the reflection durations and frequencies caused by the study building. ...
... The interaction between climate, urban form and building performance has gained substantial attention. Current studies has explored the influence of the Urban Heat Island (UHI) on the cooling demand of buildings [1,2], the relationship between geometry of urban canyons and energy consumption [3] and the effect of building form and urban density on solar access [4,5] and ventilation [6]. Worldwide governments are setting targets to building sector energy consumption. ...
Solar reflections are often unavoidable in an urban environment, however as numerous instances around the world have proven; reflections can pose serious risks to human safety by impairing vision and/or causing undesirable or even dangerous heat gains. The authors have developed a computational tool, which accurately and rapidly predicts reflected irradiance levels at varying temporal and spatial resolutions. This tool allows for high-fidelity simulations of how the visible and thermal energy reflected by a building will impact its environment at the early stages of design. This understanding can then inform decision making regarding façade geometry and materiality. This paper describes the methodology followed in creating the tool and validation of its predictions. The simulation tool shows satisfactory levels of agreement with the measured data both in terms of the peak intensity and timing of the reflections for a situation where a concave façade focused reflections to an intense spot.
... Temperature data for the stations is derived from ASHRAE's (American Society of Heating, Refrigeration and Air conditioning Engineers) records covering at least 24 years before 2006 [17]. While the 2009 handbook statistical temperature data is month based, a method due to Hedrick, (2009) [43] corroborated by Thevenard, (2009) [44] and recommended in the book -is used to derive hourly data in Excel spread sheets. The book's wind data is not easily amenable to use in the computations because it is less complete. ...
... Temperature data for the stations is derived from ASHRAE's (American Society of Heating, Refrigeration and Air conditioning Engineers) records covering at least 24 years before 2006 [17]. While the 2009 handbook statistical temperature data is month based, a method due to Hedrick, (2009) [43] corroborated by Thevenard, (2009) [44] and recommended in the book -is used to derive hourly data in Excel spread sheets. The book's wind data is not easily amenable to use in the computations because it is less complete. ...
... 2012a). Based on the findings of 1453-RP (Thevenard and Gueymard, 2010), the 2009 edition of HOF introduced a completely new clear-sky radiation model that had the capability to evaluate solar irradiance components based on locallyspecified atmospheric conditions for any location in the world. The rationale for an updated clear-sky model, as well as the details about the development of that new model and of the underlying datasets of atmospheric inputs, was described in (Gueymard and Thevenard, 2009). ...
... Based on extensive research (Gueymard and Thevenard, 2009;Thevenard and Gueymard, 2010), a new form of solar irradiance model has been introduced in the 2009 HOF. This "condensed" clear-sky model is described by only two main equations: ...
The first part of this paper (Revising ASHRAE Climatic Data for Design and Standards – Part I, Overview and Data (1613-RP)) provided a summary of the changes made to the tables of climatic design conditions in the 2013 Handbook – Fundamentals. This second part describes changes that are made to the clear-sky solar radiation model. The model provides a simple way to calculate solar irradiance components from a
pair of location-specific parameters for any location in the world, and is used in particular to evaluate cooling loads in buildings.
The model was first introduced in the 2009 Handbook but frequently exhibited an apparent bias (direct normal irradiance too low, diffuse irradiance too high), which presumably resulted from a high bias in the aerosol data sets used for its derivation. This paper explains how the bias was corrected for the 2013 Handbook. Various sources of gridded aerosol data, derived from satellite observations, were combined and calibrated with sunphotometric data from 652 ground stations. A statistical analysis was performed to determine the most appropriate statistical estimator of aerosol optical depth to use. It was found that because of the log-normality distribution of that variable over monthly periods, using its median
(rather than its mean) translates into irradiance values that are more representative of average conditions. A simple linear correlation was established to correlate the median aerosol optical depth to its mean. Finally, the derivation of a condensed set of equations, which constitutes the clearsky model as it appears in the Handbook, was revised to cover a larger set of aerosol and surface albedo conditions.
The clear-sky model has been validated against clear-sky solar irradiance data from a number of research-class stations, including Darwin, Australia; Golden, CO, USA; and Xianghe, China. Based on the analysis summarized here, the clear-sky model is found to be in reasonable agreement with measured values for these stations, even under very hazy conditions.
... In stage 1, a psychrometric chart was used with the height above sea level (meters) and barometric pressure (kPa) of the Guadalupe Valley [24]. In stage 2, the range of indoor air temperature for the wine aging area was estimated, the minimum average and maximum average of the values proposed in Table 1 (a) were calculated, and the range was from 10 • C to 15 • C with a maximum limit. of 20 • C. For the production area, it was decided to use the minimum and maximum value of the values in Table 1 (b), and a range of 15 • C to 25 • C was estimated. ...
Winemaking facilities require specific interior hygrothermal conditions for wine production and aging, often necessitating the use of electromechanical cooling and humidification systems that increase energy consumption costs. This study aimed to assess the potential application of bioclimatic strategies in artisanal wine cellars within the Guadalupe Valley, Baja California, Mexico, using a quantitative theoretical method. Psychrometric charts incorporating estimated and measured meteorological data from the study area were employed to analyze bioclimatic strategies for two key areas of a wine cellar: (1) Production and (2) Aging. Our findings highlight that integrating high thermal mass and shading techniques represents an effective strategy for wine cellar design, offering reduced reliance on active systems and promoting substantial energy savings. This research underscores the viability and benefits of bioclimatic design approaches in enhancing the sustainability and efficiency of wine cellar operations, particularly in regions with specific climatic challenges. like the Guadalupe Valley.
... Their average values have been determined at prescribed locations through ASHRAE research projects RP-1453 [36] and RP-1613 [37]. Air mass exponents and are correlated to b and d through the following empirical relationships ...
... They embody the dependence of clear-sky solar radiation on local conditions, such as elevation, precipitable water content, and aerosols. Their average values have been determined at prescribed locations through ASHRAE research projects RP-1453 (Thevenard, 2009) and RP-1613 (Thevenard and Gueymard, 2009). Air mass exponents and are correlated to b and d through the following empirical relationships ...
... where Eb = direct radiation intensity (measured perpendicular to the sun) Ed = diffuse radiation intensity value (measured on a horizontal surface) E0 = Extraterrestrial Orthogonal Intensity [6] m = air mass [7] , b d τ τ = Beam and diffuse optical depths, which depend on the terrain of the area and vary during the year and an average can be obtained from ASHRAE RP-1453 [8]. ...
Solar energy is infinite and environmental-friendly energy that is widely used in many fields such as solar cells, solar roofs, solar dryers and so on. However, solar energy has never been used in anaerobic digestion processes for biogas production. The use of solar energy may accelerate the biogas reaction to achieve higher gas production rates. Hence, the purpose of this research was to study a two-stage anaerobic digestion system in combination with a greenhouse solar dryer to increase the rate of biogas production. The study consisted of two parts: the first was to study the temperature variations in greenhouse solar dryers using computational fluid dynamic techniques, and the second was to conduct two-stage anaerobic digestion integrated with the greenhouse solar dryer system for biogas production. The results showed that the average temperature and biogas production rate in the integrated two-stage anaerobic digestion system compared to a conventional system increased by 16.2% and 19.69 %, respectively
... Degree days are then solved using a balance-point temperature where heat fluxes across the building are equivalent [33]. Deriving temperature profiles and calculating heating and cooling degree-days are standard ASHRAE practices for building modeling [34]. ...
The industrial sector consumes about one-third of global energy, making them a frequent target for energy use reduction. Variation in energy usage is observed with weather conditions, as space conditioning needs to change seasonally, and with production, energy-using equipment is directly tied to production rate. Previous models were based on engineering analyses of equipment and relied on site-specific details. Others consisted of single-variable regressors that did not capture all contributions to energy consumption. New modeling techniques could be applied to rectify these weaknesses. Applying data from 45 different manufacturing plants obtained from industrial energy audits, a supervised machine-learning model is developed to create a general predictor for industrial building energy consumption. The model uses features of air enthalpy, solar radiation, and wind speed to predict weather-dependency; motor, steam, and compressed air system parameters to capture support equipment contributions; and operating schedule, production rate, number of employees, and floor area to determine production-dependency. Results showed that a model that used a linear regressor over a transformed feature space could outperform a support vector machine and utilize features more representative of physical systems. Using informed parameters to build a reliable predictor will more accurately characterize a manufacturing facility's energy savings opportunities.
... To comprehend the influence derived from weather features of hot-humid with abundant sunshine, 6 representative cities in Southeast Asia (Taipei, Hong Kong, Manila, Bangkok, Kuala Lumpur, and Singapore) were selected for the analysis. Additionally, according to the climate zone classified by ASHRAE [51], Taipei is in the zone of 2A, Hong Kong in 1A, Manila, Bangkok, Kuala Lumpur, and Singapore in 0A. It is regarded that these cities can reflect the difference of weather conditions in Southeast Asia. ...
Solar radiation makes great influence on cooling load and occupants’ well-being in hot and humid climate zone. Particularly, occupants suffered different extent of solar radiation owing to their positions; thus, assessing the spatial and temporal thermal comfort is essential. It is worthwhile to identify the relative importance of passive solar design parameters for building envelope that these parameters directly affect thermal comfort and energy use. This study confirmed the distribution frequency of cooling loads and temporal thermal comfort usability of the simulation cases in selected cities based on the MRT algorithm that considered the impact of solar radiation. Based on the results, sensitivity analysis was used to analyze the relative importance of passive solar design parameters to clarify the priority when drawing up the façade design strategies. Eventually, correlation among facade parameters, energy use, thermal comfort, and geographic location is revealed. Furthermore, the improvement potential for energy-saving and thermal comfort by adjusting the variables in specific ranges is also demonstrated. The results indicated that within all selected cities, adjusting glazing type makes greatest influence on improvement potential that ranges from 22.8% to 39.5% in annual cooling load and 58.6%–87.5% in temporal thermal comfort usability, whereas the improvement potential for orientation is weaker than other parameters. Moreover, the absolute effect of solar design determinants is also disclosed respectively to discuss the importance of each parameter. Comprehensively, the proposed findings are expected to act as instruction when formulating the passive building envelope design related to solar radiation.
... Concerning the indoor environment quality, the EN15251 [34] introduced a ranking standard for thermal comfort based on PPD, [33] including four levels: I、II、III and IV (Table 5). Through calculating the changing PPD values by an adequate prolonged period of time and add up the time fraction they fall respectively within the range of I、II、III and IV, Marino et al [35] formulated a single and simple index through the Time Fraction Weighted Mean Vector, named Environmental Quality Index (EQI). ...
Glazed facades are broadly applied in modern architecture especially office buildings. However, glass enables massive heat transmitted into buildings that leads to thermal discomfort and energy profligacy particularly in hot-humid climate zone. Considering the strategies of energy use and thermal comfort at initial design process is beneficial for building performance, while there is shortage of approachable method to easily involve in building energy modeling or thermal comfort assessment. To enhance the connection of architecture design and building environment, this study proposed a guide map to provide visualized information from the aspects of energy use and thermal comfort through simulating the performance of different composition of glazed facade parameters. Specifically, cases with various facade configurations located in Southeast Asia cities are set to demonstrate the cooling load and long-term thermal comfort evaluation, including Environmental Quality Index (EQI), Spatial Thermal Comfort Availability (sTCA), and Temporal Thermal Comfort Usability (tTCU). Furthermore, a comprehensive thermal parameter called facade solar aperture is suggested to describe the performance of solar gains from facade; eventually, correlation among facade parameters, energy use, thermal comfort, and geographic location is disclosed. The results also indicated that to eliminate the discomfort for maintaining the condition of PMV = 0.5, the setting temperature of air-conditioning needs to be decreased by 2 °C ∼ 3 °C which corresponding to the increasing cooling load of 142.5 MJ/m² to 215.0 MJ/m². Comprehensively, through the proposed method, architects can obtain optimal schemes of different parameters, then balance the energy conservation and thermal comfort through better glazed facade design strategies.
... During the four decades that followed, the ASHRAE model has been completely transformed. The first major overhaul of the model's structure, now using pseudo optical depths for direct and diffuse radiation, was undertaken in 2009 [1,2]. These optical depths were determined from realistic estimates of monthly-mean aerosol optical depth (AOD), precipitable water (PW), and other atmospheric constituents, and were tabulated as location-specific coefficients in the 2009 edition of the ASHRAE Handbook of Fundamentals. ...
... It is found that for 0.4% design condition, the dry bulb temperature in city center is 0.9 C higher than in Linate, while the MCWB and the MDBR in the city center are 1.9 C and 1.5 C lower, respectively. The obtained climatic differences between Linate airport and Brera weather station are in agreement with the UHI effects reported in literature [89]. ...
Optimal sizing of peak loads has proven to be an important factor affecting the overall energy consumption of heating ventilation and airconditioning (HVAC) systems. Uncertainty quantification of peak loads enables optimal configuration of the system by opting for a suitable size factor. However, the representation of uncertainty in HVAC sizing has been limited to probabilistic analysis and scenario-based cases, which may limit and bias the results. This study provides a framework for uncertainty representation in building energy modeling, due to both random factors and imprecise knowledge. The framework is shown by a numerical case study of sizing cooling loads, in which uncertain climatic data are represented by probability distributions and human-driven activities are described by possibility distributions. Cooling loads obtained from the hybrid probabilistic-possibilistic propagation of uncertainty are compared to those obtained by pure probabilistic and pure possibilistic approaches. Results indicate that a pure possi-bilistic representation may not provide detailed information on the peak cooling loads, whereas a pure probabilistic approach may underestimate the effect of uncertain human behavior. The proposed hybrid representation and propagation of uncertainty in this paper can overcome these issues by proper handling of both random and limited data.
... T db = T db,max -β T db-r and (13) T wb = T wb,max -β T wb-r where β is a daily temperature profile shape factor which varies between 0 and 1 [8]; Hedrick [9] and Thevenard [10] showed it to represent accurately both dry-bulb and wet bulb temperature variations on design days. iii-instantaneous values are interpolated from hourly values using cubic splines. ...
The paper presents an integral computational model for the prediction of the
thermal performance of a conceptual two-floor, zero energy house (ZEH) in the
Arabian desert. The ZEH is powered by PV modules which shade the roof
during the day time and retract at night to expose it the sky, thus enhancing night
time cooling. The house boasts all modern comforts, including air-conditioning.
Solar radiation models coupled with recently published ASHRAE environmental
data and models are integrated with a time dependent heat conduction model to
predict the heating and cooling loads, for given equipment and storage
characteristics. The application of the computational model is demonstrated by
employing it to predict the effect of various design parameters on performance
and equipment sizing, for a typical desert site in the Kingdom of Saudi Arabia.
Keywords: zero-energy-house, solar energy, desert environment, sustainability,
modelling.
1 Introduction
The paper is concerned with the presentation and application of an efficient
computational model for the investigation of the thermal performance of the
integrated energy systems in a modern two floor, zero energy house (ZEH)
located in the Arabian desert. Solar energy drives the whole energy system after
being converted to electrical energy employing roof mounted PV modules.
Several investigations have been reported in the past for single floor, roof
mounted ZEH designs, e.g. Serag-Eldin [1] and Beshr et al. [2], as they are much
less challenging to meet the zero external energy requirement than for two floor
houses. A two floor ZEH design was considered by Serag-Eldin [3], however
synthetic data was used for solar radiation and environmental properties and only
... The earliest available models suggest a sinusoidal profile between the daily maximum and minimum temperatures. However more recent work of Hedrick (Hedrick 2009) and Thevenard (Thevenard 2009), ASHRAE (ASHRAE 2009) has further updated the latter model. T is the minimum temperature of the day and max T is the maximum temperature of the day. ...
... 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 earliest available models suggest a sinusoidal profile between the daily maximum and minimum temperatures. However, more recent work of Hedrick [34], Thevenard [35] and ASHRAE [26] has further updated the latter model. Table 13 gives the hourly temperature profile, expressed in terms of a presently defined Z-parameter (ratio of hourly temperature elevation to daily range {¼(T h 2 T min )/(T max 2 T min )}, dimensionless). ...
Terrestrial temperature records have existed for centuries. These records are available for very many locations. Temperature
is indeed the most widely measured meteorological parameter. In contrast, solar radiation being a parameter of secondary importance
and also in view of the excessive measurement cost and the associated due care, it is recorded very infrequently. This article
presents evaluation of a new type of model for mean-daily and hourly solar radiation based on temperature. The proposed model
is of a very simple constitution and does not require any secondary meteorological parameters as required by other group of
models that are available in literature. Furthermore, hourly temperature models are also presented that only require mean-daily
temperature data. A comparison was undertaken regarding the performance of the presently proposed and previous models. It
was found that the present models are able to provide reliable irradiation and hourly temperature estimates with a good accuracy.
Quantification of shading effects from complex terrain on solar radiation is essential to obtain precise data on incident solar radiation in mountainous areas. In this study, a machine learning (ML) approach is proposed to rapidly estimate the shading effects of complex terrain on solar radiation. Based on two different ML algorithms, namely, Ordinary Least Squares (OLS) and Gradient Boosting Decision Tree (GBDT), this approach uses terrain-related factors as input variables to model and analyze direct and diffuse solar radiation shading rates. In a case study of western Sichuan, the annual direct and diffuse radiation shading rates were most correlated with the average terrain shading angle within the solar azimuth range, with Pearson correlation coefficients of 0.901 and 0.97. The GBDT-based models achieved higher accuracy in predicting direct and diffuse radiation shading rates, with R2 values of 0.982 and 0.989, respectively, surpassing the OLS-based models by 0.081 and 0.023. In comparisons between ML models and classic curve-fitting models, the GBDT-based models consistently performed better in predicting both the direct radiation shading rate and the diffuse radiation shading rate, with a standard deviation of residuals of 0.330% and 0.336%. The OLS-based models also showed better performance compared to the curve-fitting models.
The design day is the basis for calculating the cooling load, and a reasonable design cooling load is essential for balancing economics and reliability. The coincidence among weather parameters of design day is a key means to ensure the accuracy, while the coincident design-day hourly variation coefficients are less considered in existing studies. For this reason, this paper proposes a method to establish the coincident hourly variation coefficient for design days. The method first extracts the normalized hourly variation coefficients from 30 years of historical weather data. Based on this, a three-parameter coupled coefficient joint matrix is established and K-Means clustering is used to select representative coincident coefficients. Finally, a “typical line” method based on the weighting idea is proposed, and the final coincident design-day hourly variation coefficients are selected from the actual weather. To verify the rationality of the new method, different load scenarios were constructed with three design days and five typical buildings, and the rationality index was established by the ratio of indoor to outdoor risk levels. The results show that the rationality of the new method reaches 0.81, while the original method (Chinese and ASHRAE standard) is only 0.03 and 0.25 in Tianjin; further study shows that the new method is applicable in different climate zones and between different typical buildings, which provides a basis for the improvement of the existing design day generation method.
This study exams the impact of climate change on outdoor design conditions and peak loads of five Chinese cities over the five major climate zones for the winter and summer conditions. The design dry-bulb temperature (DDBT) and the coincident wet-bulb temperature (CWBT) for two 30-year periods; 1971–2000 and 1984–2013 were analysed. It was found that the DDBT of the period 1984–2013 was higher than that of the period 1971–2000, whereas the CWBT and the corresponding outdoor enthalpy of the period 1984–2013 was lower than that of 1971–2000 at the various cumulative frequencies. This trend implies that the increment in conductive heat gain through the building envelope due to the rising temperature can be lower than the reduction in fresh air load due to the lower outdoor air enthalpy. In this case, the peak cooling loads may reduce in all five cities under study, and this is different from the widely held view that global warming will lead to more stringent outdoor design conditions, higher peak cooling loads and larger heating, ventilation and air conditioning (HVAC) plants than the current or historical status. The implications to the “free-cooling” of HVAC systems with enthalpy control are discussed as well.
The building peak cooling load calculation is one of the fundamental steps to develop a proper whole-building HVAC system design. The accuracy of the calculation not only impacts the system size, but also influences the building’s performance over the long run since over-sized or under-sized HVAC systems can exhibit less than optimal operation. Therefore, an accurate, easy-to-use method has been a goal for over sixty years in the United States. To date, ASHRAE has published five methods for determining building peak cooling loads, including: the Total Equivalent Temperature Difference/Time Averaging (TETD/TA) method, the Transfer Function Method (TFM), the Cooling Load Temperature Difference/Solar Cooling Load/Cooling Load Factor (CLTD/SCL/CLF) method, the Heat Balance Method (HBM), and the Radiant Time Series Method (RTSM). This paper presents the results of a comprehensive comparison of these building peak cooling load calculation methods with a focus on the sensible building envelope cooling loads. The results show that the HBM is the most accurate method, followed by the RTSM, the TFM, the TETD/TA method, and the CLTD/SCL/CLF method.
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.
In general, building energy performance is evaluated with a detailed transient building energy simulation program. However, energy evaluation tools with the bin method are still used, because of their simple and easy way to calculate building energy performance, without reducing their precision. In this research, several heating and cooling degree day methods are compared, and evaluated with their performance for variable base temperature. This analysis considered about ten years of the continuous outdoor temperature, in the Seoul and Busan areas. It is concluded that the simplified bin method is more or less acceptable for Seoul and Busan, compared with the detailed hourly bin method.
The probability function of degree days below the base 65° F. is derived from the temperature probability function. Standard statistical analysis is applied to this function to obtain the relationship between mean degree days and mean temperature. This relationship is modified for use with available data and applied in the conversion of a monthly normal temperature for Detroit to the corresponding degree day normal.
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.
Three alternatives to the existing ASHRAE clear sky irradiation model are offered to improve the accuracy of the predictions and the range of application. In rising order of complexity, these alternatives are: Revised constants which take into account the advancement in solar radiation research over the past two decades; An easy algorithm that uses the horizontal visibility at ground level as a parameter of turbidity instead of monthly constants in conjunction with clearness numbers; and Same as the former with an additional humidity term to account for variable water vapor absorption. The proposed changes will improve the accuracy of the model; the latter two will also transform the ASHRAE model into a truly universal model, not restricted by regional peculiarities.
Heating engineers sometimes have need for normal degree days for bases other than 65° F. Further analysis of the relationship between mean temperature and mean degree days for base 65° F. showed that the form of this relationship is independent of the base. This makes it possible to vary the base to any value and hence to compute degree-day normals for any base from normal temperature. Results are presented for selected stations for bases ranging from 35° to 70° F.
A simple method is presented for accurately computing the degree-days to any base temperature. The method is based on an assumed annual normal distribution of the daily mean temperatures around the monthly mean temperature. A maximum of prediction error of only 0.28 degree-days per day was observed when compared to actual weather data at four representative locations.
Equations are developed for obtaining mean monthly degree days above any base from mean monthly tem- perature and standard deviation of monthly average temperature. By the use of data for all months for twelve widely scattered stations and four bases it is shown that the truncation coefficient for degree days below any base with proper modification of the argument also applies for degree days above any base. This is also proved analyti- cally, which leads to some further aspects of the universality of the truncation coefficient. Two formulas for the coefficient are also developed.
An analysis of solar-radiation records obtained at Scarborough, Ontario, indicates that the insolation in Canada can be significantly greater than the values given by Moon's1 standard solar-radiation curves. It is possible to represent the solar data by a single analytical expression involving an atmospheric extinction coefficient and an apparent value of the solar constant. This expression allows the calculation of insolation on any surface and the determination of the time and date when the maximum insolation can occur for any surface. Simple expressions relate the time, date, latitude, building orientation, and the type of window glass and shading with the solar heat gain through windows. These can be used to program any digital computer to compute design values of the instantaneous heat gain through the windows of a building.