Comparison of the EN 15251 and Ashrae Standard 55 adaptive thermal comfort models in the context of a Mediterranean climate

Strong heat waves in the past decade and resulting legal cases which gave full responsibility for indoor thermal comfort to building professionals lead to an increased uncertainty how to maintain thermal comfort in offices without the use of a cooling system. Adaptive thermal comfort standards such as EN 15251 and Ashrae Standard 55 provide methodologies to evaluate comfort in naturally ventilated spaces. Based on a parametric study for a typical cellular office in the context of Athens, Greece, and using the building simulation software EnergyPlus, this study investigates the potentials for the applicability of natural ventilation in a Mediterranean climate. The Ashrae Standard 55 and EN 15251 adaptive thermal comfort models are compared in this context, and conclusions are drawn how the use of natural ventilation based on adaptive models can be further encourgaged.

Occupants' adaptive responses and perception of thermal environment in naturally conditioned university classrooms

A year-long field study of the thermal environment in university classrooms was conducted from March 2005 to May 2006 in Chongqing, China. This paper presents the occupants’ thermal sensation votes and discusses the occupants’ adaptive response and perception of the thermal environment in a naturally conditioned space. Comparisons between the Actual Mean Vote (AMV) and Predicted Mean Vote (PMV) have been made as well as between the Actual Percentage of Dissatisfied (APD) and Predicted Percentage of Dissatisfied (PPD). The adaptive thermal comfort zone for the naturally conditioned space for Chongqing, which has hot summer and cold winter climatic characteristics, has been proposed based on the field study results. The Chongqing adaptive comfort range is broader than that of the ASHRAE Standard 55-2004 in general, but in the extreme cold and hot months, it is narrower. The thermal conditions in classrooms in Chongqing in summer and winter are severe. Behavioural adaptation such as changing clothing, adjusting indoor air velocity, taking hot/cold drinks, etc., as well as psychological adaptation, has played a role in adapting to the thermal environment.

Climate change sensitivity of comfort and energy performance criteria for offices

The climate change scenarios of the Intergovernmental Panel on Climate Change (IPCC) predict a significant increase in temperatures over the next decades. Architecture and building occupants have to respond to this change, but little information is currently available in how far the predicted changes are likely to affect comfort and energy performance in buildings. This study therefore investigates the climate change sensitivity of the following parameters: adaptive thermal comfort according to Ashrae Standard 55 and EN 15251, energy consumption, heating and cooling loads, and length of heating and cooling periods. The study is based on parametric simulations of typical office room configurations in the context of Athens, Greece. They refer to different building design priorities and account for different occupant behaviour by using an ideal and worst case scenario. To evaluate the impact of the climate change, simulations are compared based on a common standard weather data set for Athens, and a generated climate change data set for the IPCC A2 scenario. The results show a significant impact of the climate change on all investigated parameters. They also indicate that in this context the optimisation of comfort and energy performance is likely to be related to finding the best possible balance between building (design) and occupant behaviour and other contextual influences, rather than a straightforward optimisation of separated single parameters.

Impact of climate change on thermal comfort and energy performance in offices - a parametric study

This paper investigates the impact of climate change on comfort and energy performance in offices in relation to the influence of building design and occupants. It focuses on a typical cellular office room in the context of Athens, Greece, as input for a parametric study using the building simulation software EnergyPlus. Three different building design variations are combined with two different occupant scenarios and 4 different weather data sets for IPCC climate change scenario A2.

For naturally ventilated buildings adaptive thermal comfort is evaluated according to ASHRAE Standard 55 and EN 15251. For mixed mode context evaluation is focused on greenhouse gas emissions and peak heating / cooling loads. Results indicate significant impact of the climate change on thermal comfort, and deviations between both comfort models. Comparing climate change, building design and occupant scenarios indicates that building design is the predominant influence on thermal comfort, whereas occupants are the predominant influence on greenhouse gas emissions.

Key influences on office comfort and energy performance in different climates

This paper investigates the magnitude of influence of climate, architectural design and occupants on thermal comfort and final energy consumption in offices in different climates. A parametric study for a typical cellular office room has been conducted using the simulation software EnergyPlus. Two different occupant scenarios are each compared with three different architectural design variations and modelled in the context of three different locations for the IPCC climate change scenario A2 for 2030. The parameters evaluated in this study are final energy consumption and adaptive thermal comfort according to ASHRAE Standard 55. The study shows that the impact of occupants on final energy performance is larger than the impact of architectural design in all investigated climates, but the impact of architectural design is predominant concerning thermal comfort. Warmer climates show larger optimisation potential for comfort and energy performance in offices compared to colder climates.

Feasibility Study of Solar Driven Underground Cooling System

In the United States the peak electrical use occurs during the summer. In addition, the building sector consumes a major portion of the annual electrical energy consumption. One of the main energy consuming components in the building sector is the Heating, Ventilation, and Air-Conditioning (HVAC) systems. This research studies the feasibility of implementing a solar driven underground cooling system that could contribute to reducing building cooling loads. The developed system consists of an Earth-to-Air Heat Exchanger (EAHE) coupled with a solar chimney that provides a natural cool draft to the test facility building at the Solar Energy Research Test Facility in Omaha, Nebraska. Two sets of tests have been conducted: a natural passively driven airflow test and a forced fan assisted airflow test. The resulting data of the tests has been analyzed to study the thermal performance of the implemented system. Results show that: The underground soil proved to be a good heat sink at a depth of 9.5ft, where its temperature fluctuates yearly in the range of (46.5°F-58.2°F). Furthermore, the coupled system during the natural airflow modes can provide good thermal comfort conditions that comply with ASHRAE standard 55-2004. It provided 0.63 tons of cooling, which almost covered the building design cooling load (0.8 tons, extreme condition). On the other hand, although the coupled system during the forced airflow mode could not comply with ASHRAE standard 55-2004, it provided 1.27 tons of cooling which is even more than the building load requirements. Moreover, the underground soil experienced thermal saturation during the forced airflow mode due to the oversized fan, which extracted much more airflow than the EAHE ability for heat dissipation and the underground soil for heat absorption. In conclusion, the coupled system proved to be a feasible cooling system, which could be further improved with a few design recommendations.

Análise do conforto térmico na obra de João Filgueiras Lima, Lelé: Hospitais Sarah de Salvador e do Rio de Janeiro

Estratégias passivas de projeto reduzem significativamente o uso de ar condicionado e melhoram o conforto térmico dos usuários. Isto pode ser ilustrado através dos hospitais da Rede Sarah Kubitschek projetados pelo arquiteto João Filgueiras Lima, Lelé, cujas soluções além de propiciarem ambientes mais agradáveis e salubres, evitam o uso de sistemas mecânicos de resfriamento, reduzindo o consumo de energia elétrica. Deste modo, o presente artigo tem como objetivo avaliar o conforto térmico dos hospitais Sarah de Salvador e do Rio de Janeiro, através de medições in loco da temperatura do ar, umidade relativa do ar e velocidade do ar. A análise dos resultados foi baseada em leituras de projeto, na norma ASHRAE Standard 55/2004 e em parâmetros adquiridos na literatura especializada. Os resultados demonstram a preocupação de Lelé na incorporação de aspectos bioclimáticos nos projetos. No Sarah - Salvador, alguns ambientes permaneceram fora da zona de conforto no período do meio dia, devido ao ganho de calor pela cobertura. No entanto, o uso da ventilação natural auxilia no efeito de resfriamento, melhorando o conforto térmico nos espaços internos. Já no Sarah - Rio, todos os ambientes permanecem dentro da zona de conforto proposta pela ASHRAE 55.

Análise do impacto do sombreamento vegetal no conforto termo-luminoso em edificações no clima quente e úmido

Este trabalho visa analisar o potencial do sombreamento vegetal no edifício para promover conforto térmico, luminoso e eficiência energética, a partir de simulações computacionais nos softwares DesignBuilder e Daysim. Foram simuladas diferentes combinações de fator de céu visível (FCV), transparência da copa vegetal e percentual de abertura da fachada (PAF) para edificação residencial térrea em Nata/RN, a fim de quantificar os impactos e propor recomendações projetuais. Os modelos foram analisados por meio do método de conforto adaptativo indicado pela ASHRAE Standard 55 (ASHRAE, 2010), classificação do nível de eficiência energética do Regulamento Técnico da Qualidade para o Nível de Eficiência Energética de Edificações Residenciais (RTQ-R), resultados de Daylight autonomy (DA) e uniformidade da luz natural para as exigências lumínicas de 100-300-500 lux. Os resultados demonstram grande potencial para integração da vegetação na edificação, principalmente para os fatores de céu médio e grande, e falta de coerência do RTQ-R para classificar as edificações da Zona bioclimática 08 pelo método de simulação.

Análise do impacto do sombreamento vegetal no conforto termo-luminoso em edificações no clima quente e úmido

Este trabalho visa analisar o potencial do sombreamento vegetal no edifício para promover conforto térmico, luminoso e eficiência energética, a partir de simulações computacionais nos softwares DesignBuilder e Daysim. Foram simuladas diferentes combinações de fator de céu visível (FCV), transparência da copa vegetal e percentual de abertura da fachada (PAF) para edificação residencial térrea em Nata/RN, a fim de quantificar os impactos e propor recomendações projetuais. Os modelos foram analisados por meio do método de conforto adaptativo indicado pela ASHRAE Standard 55 (ASHRAE, 2010), classificação do nível de eficiência energética do Regulamento Técnico da Qualidade para o Nível de Eficiência Energética de Edificações Residenciais (RTQ-R), resultados de Daylight autonomy (DA) e uniformidade da luz natural para as exigências lumínicas de 100-300-500 lux. Os resultados demonstram grande potencial para integração da vegetação na edificação, principalmente para os fatores de céu médio e grande, e falta de coerência do RTQ-R para classificar as edificações da Zona bioclimática 08 pelo método de simulação.

Assessing the natural ventilation cooling potential of office buildings in different climate zones in China

This paper presents an investigation of the natural ventilation cooling potential (NVCP) of office buildings in the five generally recognised climate zones in China using the Thermal Resistance Ventilation (TRV) model, which is a simplified, coupled, thermal and airflow model. The acceptable operative temperature for naturally conditioned space supplied by the ASHARE Standard 55-2004 has been used for the comfort temperature setting. Dynamic simulations for a typical office room in the five representative cities, which are Harbin, Beijing, Shanghai, Kunming and Guangzhou, have been carried out. The study demonstrates that the NVCP depends on the multiple impacts of climate, the building's thermal characteristics, internal gains, ventilation profiles and regimes. The work shows how the simplified method can be used to generate detailed, indoor, operative temperature data based on the various building conditions and control profiles which are used to investigate the NVCP at the strategic design stage. The simulation results presented in this paper can be used as a reference guideline for natural ventilation design in China.

Desenvolvimento de estrutura para purificação de água potável, através da irradiação de UV com lâmpadas fluorescentes especiais

Pós-graduação em Engenharia Elétrica - FEIS

User-centered video quality assessment for scalable video coding of H.264/AVC standard

Scalable video coding of H.264/AVC standard enables adaptive and flexible delivery for multiple devices and various network conditions. Only a few works have addressed the influence of different scalability parameters (frame rate, spatial resolution, and SNR) on the user perceived quality within a limited scope. In this paper, we have conducted an experiment of subjective quality assessment for video sequences encoded with H.264/SVC to gain a better understanding of the correlation between video content and UPQ at all scalable layers and the impact of rate-distortion method and different scalabilities on bitrate and UPQ. Findings from this experiment will contribute to a user-centered design of adaptive delivery of scalable video stream.

Principles on assessment of costs on standard basis – necessary or proper

The judgement in Hennessey Glass and Aluminium Pty Ltd v Watpac Australia Pty Ltd [2007] QDC 57 McGill DCJ provides valuable guidance for practitioners as to whether a range of particular costs items should be permitted on an assessment on the standard basis, and the amounts which should be allowed for such items. The items in issue included counsel’s fees and fees paid to expert witnesses. The decision also examined GST implications for the recovery of legal costs.

Compliance with standard precautions and occupational exposure reporting among operating room nurses in Australia

Occupational exposures of healthcare workers tend to occur because of inconsistent compliance with standard precautions. Also, incidence of occupational exposure is underreported among operating room personnel. The purpose of this project was to develop national estimates for compliance with standard precautions and occupational exposure reporting practices among operating room nurses in Australia. Data was obtained utilizing a 96-item self-report survey. The Standard Precautions and Occupational Exposure Reporting survey was distributed anonymously to 500 members of the Australian College of Operating Room Nurses. The Health Belief Model was the theoretical framework used to guide the analysis of data. Data was analysed to examine relationships between specific constructs of the Health Belief Model to identify factors that might influence the operating room nurse to undertake particular health behaviours to comply with standard precautions and occupational exposure reporting. Results of the study revealed compliance rates of 55.6% with double gloving, 59.1% with announcing sharps transfers, 71.9% with using a hands-free sharps pass technique, 81.9% with no needle recapping and 92.0% with adequate eye protection. Although 31.6% of respondents indicated receiving an occupational exposure in the past 12 months, only 82.6% of them reported their exposures. The results of this study provide national estimates of compliance with standard precautions and occupational exposure reporting among operating room nurses in Australia. These estimates can now be used as support for the development and implementation of measures to improve practices in order to reduce occupational exposures and, ultimately, disease transmission rates among this high-risk group.