Теоретично-експериментальний аналіз геліозахисту як частини енергоефективного будинку

The use of solar energy as a potential alternative source to ensure the heat supply to energy-efficient houses was explored. We have performed preliminary theoretical analysis of energy indicators for the combined heat supplying system when a solar window is used as part of the enclosure for an energy efficient house. In order to enhance operational effectiveness of the studied plant relative to existing solar collectors and to improve it in the structural aspect, the stratification of a heat carrier in the tank-accumulator of the combined heat supply system with a solar window was calculated.The study of operational efficiency of the experimental setup for using solar energy was carried out under the mode of circulation and gravitational motion of the heat carrier by the intensity of radiation of the solar energy simulator on the system of 600 W/m2 and 900 W/m2. Water was used as a heat carrier.We have analyzed changes in temperature of the heat carrier in the solar collector and in the tank-accumulator of the proposed combined solar heat supply system with a solar window as part of the external enclosure of an energy-efficient house.It was established that the heat carrier temperature under the circulation mode reached 26.5 °C. We have also presented comparative field, laboratory, and theoretical calculations of the average temperature of the heat carrier in the tank-accumulator under the mode of the heat carrier gravitation motion under various conditions.Efficiency of the experimental setup was calculated. The dynamics of change in efficiency of the solar heat supply system with a solar window were described. Efficiency was ≈55 % under the mode of heat carrier circulation for heat energy accumulation in the tank-accumulator, depending on heating duration. Under the mode of gravitational motion of the heat carrier, we calculated efficiency for the design of a solar window only, which was 53 %Исследовано использование солнечной энергии как потенциального альтернативного источника для обеспечения теплоснабжением энергоэффективных домов. Проведен предварительный теоретический анализ энергетических показателей комбинированной системы теплоснабжения за использование гелиоокна как части ограждения энергоэффективного дома. С целью повышения эффективности работы исследуемой установки относительно существующих солнечных коллекторов и улучшения ее в конструктивном аспекте было рассчитано стратификацию теплоносителя в баке-аккумуляторе комбинированной системы теплоснабжения с гелиоокном.Исследование эффективности работы экспериментальной установки в системе для использования солнечной энергии проводились в режиме движения циркуляции и гравитации теплоносителя по интенсивности излучения имитатора солнечной энергии на систему 600 Вт/м2 и 900 Вт/м2. В качестве теплоносителя использовали воду.Проанализировано изменение температуры теплоносителя в солнечном коллекторе и баке-аккумуляторе предложенной комбинированной системы солнечного теплоснабжения с гелиоокном как части внешней защиты энергоэффективного дома.Установлено, что температура теплоносителя в режиме циркуляции достигала 26,5 °С. Кроме этого, приведены сравнительные натурные, лабораторные и теоретические расчеты усредненной температуры теплоносителя в баке-аккумуляторе в режиме движения гравитации теплоносителя при различных условиях.Был рассчитан коэффициент полезного действия экспериментальной установки. Описана динамика изменения коэффициента полезного действия системы солнечного теплоснабжения с гелиоокном. В режиме движения циркуляции теплоносителя по накоплению тепловой энергии в баке-аккумуляторе, в зависимости от времени нагрева, КПД составлял ≈55 %. В режиме движения гравитации теплоносителя был подсчитан коэффициент полезного действия лишь конструкции гелиоокна, который составил 53 %Досліджено використання сонячної енергії як потенційного альтернативного джерела для забезпечення теплопостачанням енергоефективних будинків. Проведено попередній теоретичний аналіз енергетичних показників комбінованої системи теплопостачання за використання геліовікна як частини огородження енергоефективного будинку. З метою підвищення ефективності роботи досліджуваної установки відносно існуючих сонячних колекторів та покращення її в конструктивному аспекті, було розраховано стратифікацію теплоносія в баку-акумуляторі комбінованої системи теплопостачання із геліовікном.Дослідження ефективності роботи експериментальної установки в системі для використання сонячної енергії проводили в режимі руху циркуляції та гравітації теплоносія за інтенсивності випромінювання імітатора сонячної енергії на систему 600 Вт/м2 та 900 Вт/м2. Як теплоносій використовували воду.Проаналізовано зміну температури теплоносія в сонячному колекторі та в баку-акумуляторі запропонованої комбінованої системи сонячного теплопостачання із геліовікном як частини зовнішнього захисту енергоефективного будинку.Встановлено, що температура теплоносія в режимі циркуляції досягала 26,5 °С. Крім цього, наведено порівняльні натурні, лабораторні та теоретичні розрахунки усередненої температури теплоносія в баку-акумуляторі в режимі руху гравітації теплоносія за різних умов.Було розраховано коефіцієнт корисної дії експериментальної установки. Описано динаміку зміни коефіцієнта корисної дії системи сонячного теплопостачання із геліовікном. У режимі руху циркуляції теплоносія за накопиченням теплової енергії в баку-акумуляторі, залежно від часу нагріву, ККД становив ≈55 %. В режимі руху гравітації теплоносія було обраховано коефіцієнт корисної дії лише конструкції геліовікна, що становив 53

Heat Flow in Building Components, Experiment and Analysis

Three building components exposed to natural climate were studied: a dynamic insulation in the ceiling of a house, an outer wall and one window in the same wall. The term dynamic insulation implies that part of the inlet or exhaust air passes through the insulation of a house. A house with dynamic insulation was continuously measured for approximately a year and a half. The performance of the dynamic insulation was estimated by using hourly values of the temperature distribution inside the insulation. The air flow through the insulation was calculated as the air flow that best matched the measured temperature distribution. For the calculations both the transient and steady state heat transfer equations were used. The dynamic U-value for the insulation was about 0.05 W/m2°C for the ceiling. This corresponds to a dynamic energy efficiency for the insulation of 35%. Taking into account that only 40% of the total supply air passed through the insulation, the total efficiency became 14%. A heat exchanger for ventilation air have an efficiency above 60%. The general conclusion from the measurements was that dynamic insulation requires a house constructed to much higher standards, as far as air leakage is concerned, in order to work properly. An outer ambient wall with a window were studied with both theoretical analyses and measurements performed under conditions with natural climate. The method used was to estimate the heat flow through wall and window from measured temperatures and solar radiation. The longwave radiation was calculated from surface temperatures. The convective heat transfer was calculated as the difference between the heat flow through the building element and the longwave radiation. With the one-dimensional dynamic heat transfer model for the window which included shortwave radiation it was possible to measure the continuous heat flow through a window from temperature sensors and solar radiation measurements. With the one-dimensional finite difference model for the heat transfer through the wall it was possible to calculate the heat flow through a wall from temperature sensors. It was possible to continuously measure the convective heat transfer coefficient on the inner surface of a wall or a window. The accuracy was not very good: at best ±15% for the window and ± 20% for the wall. Even with this low accuracy the effect of different heating and ventilation strategies on the inside could clearly be detected. The results showed that the importance of the ventilation design and the position of the radiator is crucial. Local convective heat transfer coefficients may be more than 10 times the expected, due to ventilation or position of the radiator

Nexus of thermal resilience and energy efficiency in buildings: A case study of a nursing home

Extreme weather events become more frequent and severe due to climate change. Although energy efficiency technologies can influence thermal resilience of buildings, they are traditionally studied separately, and their interconnections are rarely quantified. This study developed a methodology of modeling and analysis to provide insights into the nexus of thermal resilience and energy efficiency of buildings. We conducted a case study of a real nursing home in Florida, where 12 patients died during Hurricane Irma in 2017 due to HVAC system power loss, to understand and quantify how passive and active energy efficiency measures (EEMs) can improve thermal resilience to reduce heat-exposure risk of patients. Results show that passive measures of opening windows and doors for natural ventilation, as well as miscellaneous load reduction, are very effective in eliminating the extreme dangerous occasions. However, to maintain safe conditions, active measures such as on-site power generators and thermal storage are also needed. The nursing home was further studied by changing its location to two other cities: San Francisco (mild climate) and Chicago (cold winter and hot summer). Results revealed that the EEMs' impacts on thermal resilience vary significantly by climate and building characteristics. The study also estimated the costs of EEMs to help stakeholders prioritize the measures. Passive measures that may not save energy may greatly improve thermal resilience, and thus should be considered in building design or retrofit. Findings from this study indicate energy efficiency technologies should be evaluated not only by their energy savings performance but also by their influence on a building's resilience to extreme weather events

n/a

The effect of the sun and its path on thermal comfort and energy consumption in residential buildings in tropical climates constitutes serious concern for designers, building owners and users. Passive design approaches based on the sun and its path have been identified as a means of reducing energy consumption, as well as enhancing thermal comfort in buildings worldwide. Hence, a thorough understanding regarding the sun path is key to achieving this. This is necessary due to energy need, poor energy supply and distribution, energy poverty and over-dependence on electric generators for power supply in Nigeria. These challenges call for a change in the approach to energy related issues, especially in terms of buildings. The aim of this study is to explore the influence of building orientation, glazing and the use of shading devices on residential buildings in Nigeria. This is intended to provide data that will guide designers in the design of energy efficient residential buildings. The paper used EnergyPlus software to analyze a typical semi-detached residential building in Lokoja, Nigeria, using hourly weather data for a period of 10 years. Building performance was studied as well as possible improvement regarding different orientations, glazing types and shading devices. The simulation results showed reductions in energy consumption in response to changes in building orientation, types of glazing and the use of shading devices. The results indicate a 29.45% reduction in solar gains and 1.90% in annual operative temperature using natural ventilation only. This shows a huge potential to reduce energy consumption and improve people’s wellbeing using proper building orientation, glazing and appropriate shading devices on building envelope. The study concludes that for a significant reduction in total energy consumption by residential buildings, design should focus on multiple design options rather than concentrating on one or few building elements. Moreover, the investigation confirms that energy performance modelling can be used by building designers to take advantage of the sun and to evaluate various design options

Case studies of outdoor testing and analysis of building components

The construction and development of the PASSYS/PASLINK outdoor test cells were funded by the European Commission, with the objective of providing high-quality test environments for quantifying the performance of passive solar building components. Over the years since the original test cells were commissioned, the initial concept for outdoor testing has been extended to include other test cell types. Significant improvements have been made to the experimental procedures and analysis techniques, and a broad range of components has been tested. This paper describes representative experiments that have been conducted using these highly controlled outdoor test environments, indicates some of the related analysis, and shows the type of information that can be obtained from such tests. It demonstrates the way in which component performance can be ascertained in the realistic external environment. The case studies chosen range from building component tests within EC research projects to commercial tests, and from conventional building components to novel integrated facade systems. They also include a large range of passive and active components. Each case study summarises the test component, the purpose of the test, details of the test configuration (period of test, instrumentation, etc.), results and analysis, and associated modelling and monitoring where appropriate. The paper concludes with an appraisal of the advantages and limitations of the test cells for the various component types

High-Performance Integrated Window and Façade Solutions for California

The researchers developed a new generation of high-performance façade systems and supporting design and management tools to support industry in meeting California’s greenhouse gas reduction targets, reduce energy consumption, and enable an adaptable response to minimize real-time demands on the electricity grid. The project resulted in five outcomes: (1) The research team developed an R-5, 1-inch thick, triplepane, insulating glass unit with a novel low-conductance aluminum frame. This technology can help significantly reduce residential cooling and heating loads, particularly during the evening. (2) The team developed a prototype of a windowintegrated local ventilation and energy recovery device that provides clean, dry fresh air through the façade with minimal energy requirements. (3) A daylight-redirecting louver system was prototyped to redirect sunlight 15–40 feet from the window. Simulations estimated that lighting energy use could be reduced by 35–54 percent without glare. (4) A control system incorporating physics-based equations and a mathematical solver was prototyped and field tested to demonstrate feasibility. Simulations estimated that total electricity costs could be reduced by 9-28 percent on sunny summer days through adaptive control of operable shading and daylighting components and the thermostat compared to state-of-the-art automatic façade controls in commercial building perimeter zones. (5) Supporting models and tools needed by industry for technology R&D and market transformation activities were validated. Attaining California’s clean energy goals require making a fundamental shift from today’s ad-hoc assemblages of static components to turnkey, intelligent, responsive, integrated building façade systems. These systems offered significant reductions in energy use, peak demand, and operating cost in California

Predicted and in situ performance of a solar air collector incorporating a translucent granular aerogel cover

This is the post-print version of the Article. The official published version can be accessed from the link below - Copyright @ 2012 ElsevierThere is an opportunity to improve the efficiency of flat plate solar air collectors by replacing their conventional glass covers with lightweight polycarbonate panels filled with high performance aerogel insulation. The in situ performance of a 5.4m2 solar air collector containing granular aerogel is simulated and tested. The collector is incorporated into the external insulation of a mechanically ventilated end terrace house, recently refurbished in London, UK. During the 7 day test period, peak outlet temperatures up to 45 °C are observed. Resultant supply and internal air temperatures peak at 25–30 and 21–22 °C respectively. Peak efficiencies of 22–36% are calculated based on the proposed design across a range of cover types. Measured outlet temperatures are validated to within 5% of their predicted values. Estimated outputs range from 118 to 166 kWh/m2/year for collectors with different thickness granular aerogel covers, compared to 110 kWh/m2/year for a single glazed collector, 140 k h/m2/year for a double glazed collector and 202 kWh/m2/year for a collector incorporating high performance monolithic aerogel. Payback periods of 9–16 years are calculated across all cover types. An efficiency up to 60% and a payback period as low as 4.5 years is possible with an optimised collector incorporating a 10 mm thick granular aerogel cover.This work is supported by the EPSRC, Brunel University, Buro Happold Ltd. and the Technology Strategy Board