Available online 11 January 2013 Publication year: 2013 Source:Building and Environment
Exposure to indoor chemical air pollutants is expected to increase potentially the chance of developing cancer. Ambient levels of carbonyl (formaldehyde, acetaldehyde, acrolein and acetone) and BTEXs (benzene, toluene and xylenes) compounds were monitored at210 residential homes in Xicheng district, Beijing, during the period of November-December 2009. The indoor concentrations of formaldehyde, acetaldehyde, acrolein, acetone, benzene, toluene and xylenes were in the range of 0.2-213.4 μg m−3, 0.7-140.9 μg m−3, 0.1-25.2 μg m−3, 0.3-102.1 μg m−3, 1.0-47.5 μg m−3，1.3-552.6 μg m−3 and 0.2-150.6 μg m−3, respectively. Average concentrations of formaldehyde, acetaldehyde, acrolein, acetone, benzene, toluene and xylenes were 21.8 μg m−3, 16.3 μg m−3, 2.8 μg m−3, 10.7 μg m−3, 9.0 μg m−3, 32.1 μg m−3 and 12.3 μg m−3, respectively. The individual samples were mostly lower than the Chinese guideline values except formaldehyde and toluene, which showed higher values in 91 and 29 samples. Statistical analysis and I/O (indoor concentration/outdoor concentration) ratio results showed that the main sources of formaldehyde, acetaldehyde, benzene and toluene at homes with renovation age <5 years were organic solvents used in adhesives and decoration materials. Meanwhile, outdoor emission factors may have an impact on acetone, acrolein and xylenes concentrations of indoor air at different homes, and on formaldehyde, acetaldehyde, benzene and toluene concentrations of indoor air at homes with renovation age >5 years. Our results also showed that higher cancer risks for human exposure to formaldehyde, acetaldehyde and benzene than previous studies in Guangzhou and Hangzhou, China with one exception.
Highlights
► Levels of carbonyls and BTEXs were monitored at 210 homes in Xicheng district, Beijing. ► The main sources of carbonyls and BTEXs for newly decoration home were organic solvents used in adhesives. ► The indoor concentrations of carbonyls and BTEXs were also influenced by outdoor emissions.
Available online 12 January 2013 Publication year: 2013 Source:Building and Environment
This research has the goal of determining, comparing and substantiating the actual outcome of using sustainable practices, from a financial and environmental comfort point of view. The selected context was of interest due to the challenge of quality sustainable construction at controlled costs, meant for inhabitants of the Portuguese cooperative housing, due to its economical implications and especially its social ones. Two case studies of cooperative housing developments built in Portugal are presented, the first with characteristics of traditional construction and the second including sustainable building features. With these examples, it is intended to demonstrate that it is possible to build below cost limits imposed by law in order to substantially reduce energy consumption costs for heating and cooling as well as for domestic water heating. So, calculations of energy savings in indoor heating and cooling, as well as for domestic water heating are presented in this article for two specific situations: first, for a standard comfort use of housing, as opposed to a situation of real consumption of housing developments as obtained by monitoring carried out for one year in the same dwellings studied for standard comfort. The causes that lead to a substantial decrease in energy consumption in the building of sustainable construction are also described, as a starting point to the improvement of future cooperative housing. Finally are presented, for each of the two situations, calculations of the payback period of investment, according to the specific incremental cost in sustainable construction and the benefits in reducing consumptions. The results show an effective contribution to the improvement of the environment and environmental comfort, due to sustainable construction.
Highlights
►How to use efficient insulation on a small overcost basis. ► How to strongly decrease heating energy cost with very efficient insulation. ► Efficient solar collectors and DHW gas heaters reduce energy consumption up to 70%. ► Simple payback period of efficient construction estimated 2.3 to 24 years.
Available online 12 January 2013 Publication year: 2013 Source:Building and Environment
Based on the recent emergence of Controlled Radiator Valve (CRV) components, the paper considers the research, development, application and benefits of a modern control methodology to improve the heating efficiency of domestic dwellings. In particular, the problem of efficient temperature control, is formulated as a model predictive control scheme employing a parameter matching technique. A key contribution of the paper is the development of an on-line modelling method, which, in contrast to previously reported techniques, requires no prerequisite knowledge of the thermodynamic behaviour of a given controlled zone and a training period of only 48 hours. Moreover, it is shown that excellent performance is obtained without the normal requirements for measurements of site weather or input from other external sources of weather data, thereby reducing system cost and complexity. The proposed techniques are applied in a controlled zone using a BS EN 60335 oil filled heat emitter, whose input power is closely controlled using a PWM power converter within an instrumented test cell, and also in an occupied dwelling. Results demonstrated MPC can be implemented in a dwelling with minimal perquisite modelling and still achieve set point tracking when compared to more conventional solutions resulting in an energy saving of up to 22%.
Highlights
► We compared 2nd order to 5th order parameter matched models to zone heating response. ► We implemented MPC using recursively parameter matched models in a test cell. ► We implemented MPC using recursively parameter matched models in a dwelling. ► Recursive modelling is suitable for use with MPC controlling fluid filled heat emitters. ► PWM output does not reduce performance of MPC controller using recursive modelling.
Available online 16 January 2013 Publication year: 2013 Source:Building and Environment
A critical review on boundary conditions for watertightness testing was presented in a related paper forming Part I of “A uniform methodology to establish test parameters for watertightness testing”. Existing methodologies to establish test conditions only partially consider co-occurrence of rain and wind, which yields large uncertainties when determining return periods for extreme wind-driven rain events. This paper presents a new approach based on a Pareto fronts method for which wind driven rain intensities and wind pressures are derived. Straight lines can be fitted to consecutive fronts, and a generalised Pareto distribution describes the corresponding probabilities of occurrence of wind-driven rain events. Assumptions in the use of the methods are given and constraints to its use provided by means of case-studies. Advantages over existing methods for estimating watertightness test parameters are highlighted. Test conditions can be calculated for various configurations and different averaging periods depending on the failure behaviour of specific building envelop components. Subsequently it is shown that the conversion of case-based test conditions to generic test protocols and performance levels requires careful consideration. Finally, the paper provides practical guidelines on defining realistic watertightness performance levels for building envelop components.
Highlights
► Co-occurrence of rain and wind is evaluated by means of Pareto front analysis. ► A Pareto distribution allows to determine the probability of extreme WDR events. ► Based on case-studies, large discrepancies with existing methods were found. ► Guidelines on the conversion towards generic performance levels are reported.
Available online 16 January 2013 Publication year: 2013 Source:Building and Environment
This study develops a new methodology to investigate the particle residence time in indoor environment with the Lagrangian modeling. So far, the particle residence time has been only developed in terms of the Eulerian-based advection-diffusion approach, which is easy to use but is only valid for the transport of fine, neutrally buoyant, non-inertial particles that exactly follow indoor airflows. However, for practical indoor air pollution problems, there exists a wide range of particle sizes. To extend the engineering application range of the particle residence time, a new Lagrangian-based approach, which adopts the kernel concentration estimation method, is herein proposed to model the particle residence time in indoor environment. This new approach can transfer a discrete number of Lagrangian particle trajectories into an Eulerian form of particle concentrations at a given point, and thus provide the mean particle residence time. The commonly used Eulerian-based advection-diffusion approach is also considered for numerical comparison. Two representative particle sizes of 10-μm coarse particles and 1-μm fine particles are input into the two approaches to investigate the effect of particle size on the mean particle residence time. The simulated results indicate that this new Lagrangian approach can give more reasonable prediction on the particle residence time than the Eulerian-based advection-diffusion approach.
Highlights
► The new Lagrangian approach is developed to evaluate the particle residence time. ► The Eulerian advection-diffusion approach is included for numerical comparison. ► Two particle sizes are input into the two approaches to compare the difference. ► The new Lagrangian approach well predicts the particle residence time.
March 2013 Publication year: 2013 Source:Building and Environment, Volume 61
Heat stress, having physiological effects on workers, can lead to reduction of work enthusiasm and productivity, increased incident rate, heat illness, and death. This paper aims to optimize the work–rest schedule for construction rebar workers in hot and humid environment. Two objectives are addressed in the optimization process when such schedules are designed. These objectives include maximizing the labor productivity and minimizing the occurrence of heat stress on construction site. Field studies were conducted during the summer time in Hong Kong (July–September 2010–2011). The physiological conditions of rebar workers and environmental parameters of construction sites were measured and collated. Monte Carlo simulation technique was used to account for the uncertainties and variations of meteorological and physiological parameters during summer time in Hong Kong. On the basis of work-to-exhaustion-then-take-a-rest principle, an optimized work–rest schedule that maximizes productive time and at the same time safeguarding the health and safety of rebar workers is developed. An optimized schedule of having a 15 min break after working 120 min continuously in the morning (WBGT = 28.9 ± 1.3 °C), and having a 20 min break after working 115 min continuously in the afternoon (WBGT = 32.1 ± 2.1 °C) is proposed. The current study has contributed in providing an objective and scientific mechanism to optimize work–rest schedule which may benefit the industry to produce solid guidelines for working in hot weather.
Highlights
► We optimize the work–rest schedule for rebar workers in hot and humid environment. ► Monte Carlo simulation was used to account for the variations of HTT variables. ► The schedule maximizes productive time and safeguards the safety of rebar workers. ► Having a 15 min break after working 120 min in the morning is proposed. ► Having a 20 min break after working 115 min in the afternoon is proposed.
March 2013 Publication year: 2013 Source:Building and Environment, Volume 61
Post Fukushima disaster, the energy consumption perspective in Japan has changed. It initiated unprecedented exercises towards energy saving and produced interesting results. These included the ‘setsuden (energy saving)’ campaigns, which promoted the minimum indoor temperature setting of 28 °C in summer. However, there is no scientific basis for this recommendation. Japan does not have adaptive comfort standards and the ASHRAE standard-55 does not include the data from the land of the rising sun. In this context, we conducted a thermal comfort field study in four office buildings in Tokyo for three months in summer 2012. We measured all the four environmental and the two personal variables. Through a paper based field survey, we interviewed 435 occupants who returned 2402 questionnaires.The occupants' comfort temperature was found to be 27.2 °C. Thermal acceptability was very high at 89% even when 26% of the environments were outside the three central categories of the thermal sensation scale. PMV always significantly overestimated the sensation owing to a wide range of adaptations by the subjects. The indoor air speeds were low, indicating a need for ceiling fans. In 50% of the environments the indoor temperature was more than the 28 °C limit. As the buildings were designed for AC mode, running them in NV mode posed challenges. This study calls for elaborate field studies in offices in Japan for the development of custom made adaptive comfort standards.
Highlights
► Japan has no adaptive comfort standards and ASHRAE Std-55 doesn't have Japan data. ► A thermal comfort survey in Tokyo offices gave 27.2 °C as the comfort temperature. ► PMV always significantly overestimated the sensation due to an array of adaptations. ► Thermal acceptability was 89% whilst, 26% were uncomfortable on the sensation scale. ► 50% of the spaces were warmer than the 28 °C level for summer set by the government.
Available online 21 January 2013 Publication year: 2013 Source:Building and Environment
Energy-conscious design of gymnasium daylighting can contribute to significant energy savings and improve users’ playing environment. The purpose of this research is to assess the relative impact of 22 different design factors on interior daylighting effects, and to formulate design recommendations for gymnasiums in mid-latitude area of China. Each factor with very high impact: dates, latitude, window position, glazing transmittance, building height, building depth and window area was simulated under the constraints of gymnasium illumination and illumination uniformity. The window area, which has the direct relationship with daylighting, is considered as the evaluation standard for the daylighting performance of other influence factors. A complex interdependence among these daylighting factors was found. By considering daylighting and energy-saving in combination, ‘Autumnal Equinox’ at 16:00 was identified as an appropriate daylighting design date and time. Side windows are not suitable for gymnasium daylighting except in designs where there is no seating. For small gymnasiums with no seats, the lighting performance of side-windows is most influenced by glazing transmittance, building height and depth. For all sizes of gymnasium skylights, the influential factors are glazing transmittance and building height. A simplified formula was obtained via linear regression, which enables architects to quickly calculate the required window area during the preliminary design phase.
Highlights
► 22 design factors were extracted on interior daylighting effects. ► Seven factors with very high impacts were analyzed respectively. ► A simplified calculation of required window area was derived.
March 2013 Publication year: 2013 Source:Building and Environment, Volume 61
Air tightness is an important parameter for both smoke suppression in a fire and for the energy efficiency of buildings. A transient method using a sudden expansion of compressed air (SECA) was recently introduced to measure the air tightness, or effective leakage area, with the least amount of labor or preparation. Although the feasibility of SECA has been reported, relevant experimental data has been limited to small leakage areas of up to 20 cm2, which has not been sufficient to cover the leakage of rooms in buildings. In this study, a test room and the test module for SECA were modified and the basic equation of the transient method was improved. As a result, the application limit of the leakage area can be extended up to 700 cm2, and further extension would be possible simply by increasing the chamber volume or its initial pressure. The experimental results of SECA can be related theoretically to the results of a steady method, and they were not affected by the volume of the room. The results of this study will help prove the most convenient measurements for air tightness and for the effective leakage areas in rooms and ventilation systems.
Highlights
► The air tightness was measured with an improved method using a sudden expansion of compressed air (SECA). ► SECA showed very good linearity in the relationship with the actual open area and the measurable range can be easily extended. ► The relationship between the SECA and the blower method can be explained theoretically. ► SECA is the most convenient method for the practical inspection of air tightness in buildings.
Available online 21 January 2013 Publication year: 2013 Source:Building and Environment
This paper assesses the practicability of meeting the German federal government’s energy-political targets for the residential sector by analysing the potential future development of this sector in an aggregated bottom-up model. The domestic building stock is considered in terms of the likely developments in the housing market, as well as the energetic characteristics of current and future buildings. The employed method is based on deterministic projections of demand floor space and demolition/refurbishment rates. The key novelty lies in the focus on developments in this sector in Germany; existing studies have not had this focus and have therefore employed a more rudimentary methodology, for example with static refurbishment rates, shorter time horizons or no spatial differentiation. The total resulting final heating demand of domestic buildings of about 500 TWh lies above that of other studies in 2050, which is mainly due to the conservative assumptions regarding renovation activity and new build made in the present case. Hence in the reference scenario the target for 2020 is not met, suggesting that further political intervention is required. In another scenario, it is shown that a drastic increase of the renovation rate is required in order to meet the 2020 target, especially amongst existing single family buildings. The supply side is only indirectly considered due to the aggregated nature of the model, which could be improved for further work, but the presented method nevertheless represents a good compromise between using solely freely available data and obtaining superior degree of precision to previous studies.
Highlights
► A bottom-up model of the German residential sector is developed. ► The novelties are: higher granularity, longer timeframe, use of public data. ► Scenarios show a drastic action needed to meet the 2020 target. ► Policy measures should focus on owner-occupiers in single family houses. ► More detailed (public) data on heat supply systems should be sought.
March 2013 Publication year: 2013 Source:Building and Environment, Volume 61
In this paper, we propose a method for assessing renovation packages drawn up with the goal of increasing energy efficiency. The method includes calculation of bought energy demand, life-cycle cost (LCC) analysis and assessment of the building according to the Swedish environmental rating tool Miljöbyggnad (MB). In this way the methodology assesses economic, indoor environmental quality (IEQ) and specifically environmental aspects associated with energy demand of such packages from a sustainability point-of-view. Through MB, energy efficiency packages are placed in context with other necessary measures required to improve environmental performance in buildings, providing a consistent and systematic basis other than simply financial performance by which to compare capital improvements.The method is further explained and analyzed by applying it in three case studies. In each case study a multi-family building representing a typologically significant class in the Swedish building stock is considered, and for each building a base case and two renovation packages with higher initial investment requirement and higher energy efficiency are defined. It is shown that higher efficiency packages can impact IEQ indicators both positively and negatively and that packages reducing energy demand by approx. 50% have somewhat higher LCC. Identified positive IEQ impacts point to added value for packages that may not otherwise be communicated, while negative impacts identify areas where packages need to be improved, or where MB indicators may be referred to as specifications in procurement procedures.
Highlights
► Integrated environmental, economic and IEQ assessment of high-efficiency renovations. ► Positive and negative impacts on IEQ due to renovation. ► Somewhat higher LCC to meet national and international energy efficiency goals.
Available online 22 January 2013 Publication year: 2013 Source:Building and Environment
After decades of intense research, the effects of light on the circadian system have been proved to exist. By studying the relationship between human physiology and light, research has also advanced to the point that there is the belief that these effects will be in future regulated by Standards. Establishing a direct connection among the fundamental radiometric, the traditional photometric and the new circadian approach to lighting becomes a fundamental step for introducing new concepts to lighting practitioners.This theoretical paper has the aim to propose a correlation between the traditional approach to lighting design with the new and still not definitely defined circadian approach by means of a photometric to circadian correlation factor. By this way, once the circadian efficiency function will be experimentally determined, technicians will be able to evaluate also from a numerical point of view the impact of lighting on the circadian system, adding health considerations to the traditional design process.
Highlights
► approach to circadian photometry based on CIE definition of photometric quantities. ► correlation between photometric approach to lighting design and circadian approach. ► a definition of circadian metrics in parallel to traditional photometric quantities. ► conversion factors between luminous and circadian quantities are presented
Available online 23 January 2013 Publication year: 2013 Source:Building and Environment
The time series of indoor and outdoor CO concentrations in natural ventilating rooms were monitored continuously and simultaneously in summer, and the relationships between indoor and outdoor CO concentrations at two sampling locations in the central area of Shanghai were examined and discussed. Linear regression analysis was employed to correlate indoor concentration levels with outdoor concentrations, and the diurnal cycles of the indoor and outdoor CO concentrations show positive correlations at both sampling sites. The monitoring data also indicate that the indoor to outdoor ratios of CO concentrations in the test natural ventilating rooms are less than but close to 1. In addition, a predicting model based on a mass balance assumption of indoor pollutants was applied for estimating the indoor CO concentrations by using the outdoor test data as inputs, resulting in good agreement with the test curves for the two sampling sites.
Graphical abstract
Highlights
► Indoor/outdoor CO levels of natural ventilation (NV) rooms in summer were tested. ► Diurnal cycles of the indoor/outdoor CO concentrations show a positive correlation. ► I/O ratios of the CO concentrations of NV rooms are less than but close to 1. ► Indoor CO concentrations can be obtained by using the regressed outdoor CO curves.
Available online 24 January 2013 Publication year: 2013 Source:Building and Environment
To study transient mass transfers inside buildings equipped with ventilation systems, reduced-scale experiments have been performed by applying the scaling down methodology developed for studying isothermal airflows in a steady or a transient state [1]. Transient tests have been carried out both on simplified cases considered for the validation of the methodology and on two reference industrial configurations representative of real industrial facilities. In this article, focus is made on transient results obtained on simplified and reference industrial cases subjected to wind and internal overpressure effects. The main objectives are firstly to identify the internal transient airflow behaviour, compared with Helmholtz oscillated phenomena underlined from natural ventilation studies, secondly to analyse the pollutant containment of reference industrial configurations subjected to wind and/or internal overpressure effects due to an accident, and finally to check the ability of the SYLVIA code to model these transient phenomena.
Highlights
► Transient flows in ventilation systems were experimentally and numerically studied. ► Helmholtz oscillations have been characterized depending on branch characteristics. ► The ventilation system inertia can often be negligible for industrial cases studied. ► Wind turbulence can lead to unsteady losses of the containment inside buildings. ► The Sylvia code has been validated for taking into account transient flow phenomena.
Available online 24 January 2013 Publication year: 2013 Source:Building and Environment
Materials that are stored or used in damp conditions may be subject to mould growth. However, all materials are not equally susceptible; for each specific material, there is a critical moisture level for mould growth. If this is exceeded, there is a risk that mould fungi will develop on the material. This level can be determined in accelerated laboratory tests, at constant temperatures and relative humidity (RH) favourable to mould growth. Within a building however, these parameters are expected to vary from one part of the construction to another, and are seldom constant; there is fluctuation in temperature and RH due to seasonal or shorter-term variations. In this study, test pieces of the same materials tested in a laboratory environment were placed in three outdoor ventilated crawl spaces and three outdoor ventilated attics, where the temperature and RH varied, and mould growth on the test pieces was studied over 2.5 years. Material-specific mould growth curves were produced based on critical moisture levels, as determined in laboratory experiments under constant temperature and RH. When the actual conditions of RH and temperature exceeded these curves, there was mould growth on the test pieces if the time was sufficiently long. The conclusion from the study is that although conditions in laboratory studies are simplified and accelerated, the results serve well to indicate mould growth within a building construction.
Highlights
► Mould growth on building materials exposed in attics and crawlspaces was studied. ► The relative humidity and temperature conditions were monitored at each test-site. ► Growth limit curves were created based on laboratory data of critical moisture levels. ► The results were compared to results from laboratory studies. ► Laboratory tests can be used to predict mould growth in within a building
April 2013 Publication year: 2013 Source:Building and Environment, Volume 62
The purpose of this study is to evaluate the unsteady wind effects on the airflow rates of naturally ventilated buildings. A mock-up was built on the roof of a seven-story building, and was designed to be ventilated with two openings by wind-driven force. The time histories of wind speed and direction, static pressure difference across the two openings, and airflow rate were monitored simultaneously in field measurement. The field measurement was conducted during one year, from June 2010 to May 2011. The pressure coefficient at the openings is significantly influenced by the fluctuating components of the wind speed and direction, and the unsteady airflow rates are also sensitive to the fluctuating components. The differences between the unsteady state airflow rates and the quasi-steady airflow rates are significantly increased when the fluctuating component is larger than the mean component. It can also be seen that if the fluctuating component is larger than the mean component, the quasi-steady airflows model is not applicable to the unsteady airflow rates. A statistical expression for the unsteady wind effects on the unsteady airflow rates is proposed from statistical analysis.
Highlights
► We evaluate the effects of unsteady wind flow on natural ventilation rate. ► The fluctuation of wind direction is independent of wind speed. ► Directional fluctuations strongly influence the pressure coefficient. ► The statistical model for prediction of unsteady wind effects is proposed.
March 2013 Publication year: 2013 Source:Building and Environment, Volume 61
The thermal resistance (R-value) of an enclosed airspace depends on the emissivity of all surfaces that bound the airspace, the size and orientation of the airspace, the direction of heat transfer through the airspace, and the respective temperatures of all surfaces that define the airspace. A table is provided in the 2009 ASHRAE Handbook of Fundamentals (Chapter 26) that contains the R-values of enclosed airspaces. The ASHRAE table is extensively used by modellers, architects and building designers in the design for thermal resistance of building enclosures. This table provides R-values for enclosed airspaces for different values of airspace thickness, effective emittance, mean airspace temperature, and temperature differences across the airspace. The effect of the airspace aspect ratio (length/thickness) on the R-value is not accounted for in the ASHRAE table. However, in previous studies, it was shown that the aspect ratio of the airspace can affect its R-value.In this paper, previous studies undertaken by the author that focused on determining the R-value for vertical enclosed airspaces and horizontal enclosed airspaces with downward heat flow are extended to investigate the effect of the aspect ratio on the R-value of horizontal enclosed airspaces under an upward heat flow condition for different airspace thicknesses and having a wide range of values for effective emittance, mean temperature, and temperature differences across the horizontal airspaces. The R-values predicted from numerical simulation are compared with those provided in the ASHRAE table. Considerations were also given to investigate the potential increase in the R-values of enclosed airspaces when a thin sheet is placed horizontally in the middle of the airspace and whose surfaces have different values of emissivity. Thereafter, practical correlations are developed for determining the R-values of horizontal enclosed airspaces for future use by modellers, architects and building designers. The simplicity of these correlations for horizontal airspaces with upward heat flow along with those that were previously developed for vertical airspaces and horizontal airspaces with downward heat flow suggests that these correlations could be included in the ASHRAE Handbook of Fundamentals.
Highlights
► The dependence of R-value of horizontal enclosed airspace on its aspect ratio was investigated. ► The aspect ratio has more effect on the R-value of enclosed airspace of larger thickness. ► Practical correlations are developed for determining the R-values of enclosed airspaces. ► The developed correlations can be easily used by modellers, architects and building designers. ► R-value could be tripled due to installing thin sheet in the middle of enclosed airspace.
March 2013 Publication year: 2013 Source:Building and Environment, Volume 61
With building heating and cooling accounting for nearly 14% of the national energy consumption, emerging technologies that improve building envelope performance have significant potential to reduce building energy consumption. Actual savings from these technologies will depend heavily upon their performance in diverse climate and operational conditions. In many cases, early-stage research can benefit from detailed investigation in order to develop performance thresholds and identify target markets. One example, a dynamic, highly transparent, near-infrared switching electrochromic (NEC) window glazing, is the focus of this investigation. Like conventional electrochromics, the NEC glazing can dynamically tune its optical properties with a small applied voltage. Consequently, the glazing can block or transmit solar heat to reduce cooling or heating loads, respectively. Unlike conventional electrochromics, NEC glazings remain transparent to visible light, causing no adverse effect to daylighting or building aesthetics. This study utilizes the software COMFEN to simulate a broad range of NEC performance levels, for commercial and residential buildings in 16 climate-representative reference cities. These simulations are the basis for identifying performance levels necessary to compete with existing static technologies. These results indicate that energy savings are strongly influenced by blocking-state performance. Additionally, residential applications have lower performance requirements due to their characteristic internal heat gains. Finally, the most dynamic NEC performance level is simulated in competition with high performing static alternatives. Here heating and cooling energy savings range from 5 to 11 kWh/m2 yr for commercial and 8–15 kWh/m2 yr for residential, in many regions on the order of 10%.
Highlights
► We model a new transparent electrochromic window glazing in a south-facing façade. ► Simulations are done for 16 climate regions in commercial and residential facades. ► Performance levels are determined to outperform existing window technologies. ► Overall heating and cooling savings depend most on how well solar heat is blocked. ► In some regions and buildings, heating/cooling savings from this glazing exceed 10%.
March 2013 Publication year: 2013 Source:Building and Environment, Volume 61
This study proposes an Artificial Neural Network (ANN)-based thermal control method for double skin envelope buildings in winter. A thermal control logic for controlling heating systems and openings on the internal and external envelopes of a double skin building was developed using the ANN-based predictive and adaptive control model. Employing the predicted values for the future indoor air temperature (i.e., the air temperature rise or drop by the next control cycle), the control logic predetermines the operation of the heating system and the opening conditions of internal and external envelopes of a double skin building.After the parametrical optimization of the initial ANN model, the performance of the optimized ANN model was tested for prediction accuracy and adaptability using the data measured from an actual double-skinned envelope building. The analysis results revealed that the ANN model proved its prediction accuracy and adaptability for the different climate conditions and envelope orientations. The developed control logic and model in this study are effectively applied for thermal control of double skinned envelope buildings.
Highlights
► Proposes an Artificial Neural Network (ANN)-based thermal control method for double skin envelope buildings in winter. ► A thermal control logic was developed using the ANN-based predictive and adaptive control model. ► The performance of the optimized ANN model was tested for prediction accuracy and adaptability. ► The developed control logic and model are effectively applied for thermal control of double skinned envelope.
