Five-year measurements of thermal performance for a semi-underground test house

In order to obtain fundamental data on the thermal performance of a semi-underground room, a twin-type test house was constructed on the campus of Tohoku University in September 1984. The test house has two rooms with south-facing windows above the ground surface, and a corridor between the two rooms. The floor level is 1.3m below the ground surface. Thermal insulation 0.1m deep and 1.35m wide was installed horizontally around the room on the east at a level 0.3m below the ground surface. The room on the west has no such “horizontal” insulation. Five-year measurements of air temperatures in both rooms, soil temperatures around the rooms, energy consumption for space heating, and so forth were made in four different situations. An experimental study found that horizontal insulation was effective in reducing the annual temperature fluctuation of indoor air, and in reducing the heating load. These effects, which were also analyzed from the viewpoint of heat balance in the room, were verified by computer calculations based on the two-dimensional finite element method.     

Performance details of a rotating prism solar wall

The “kinetic wall” discussed in the First International Symposium in this series has been incorporated into a passive solar house that was built at Sede Boqer, Israel. The house has been lived in and monitored since October 1982. The present paper shows an analysis of the first winter's thermal performance figures of the rotating prism wall and compares it with some more conventional passive heating methods that are employed in the other rooms of the house.During the heating period from November 1st 1982 until March 31st 1983, the average ambient temperature at Sede Boqer was 10.5°C with a mean diurnal temperature swing of ±5.0°C. By contrast, the average air temperature in the room heated by the kinetic wall was 18.0°C with a mean diurnal temperature swing of magnitude less than ±1.0°C. No backup heating was necessary in this room.The rotating prism wall has proved to be easy to realize, convenient to live with and a remarkably effective space heating device.     

Reduction of heat flux by a flowing water layer over an insulated roof

This communication presents an investigation of the reduction of heat flux by the flow of water over an insulated roof; the water surface is exposed to periodic solar radiation and atmospheric air while the bottom of the insulation is in contact with the room air at a constant temperature (corresponding to an air conditioned building). The heat conduction equation characterizing the temperature distribution in the roof/insulation, has been solved using appropriate periodic boundary conditions. It is seen that as the flow velocity increases, the heat flux coming into the room decreases while the heat taken away by the flowing water increases. It is concluded that the maintenance of a flowing water layer over an insulated roof is to a great extent more effective than a roof pond system; to some extent it is also more effective than a water film spray system over the roof for reduction of the cooling load of a building.     

Comparative thermal performance of new and old houses

The commitment to reduce energy consumption in buildings has focused attention on improving thermal insulation by employing measures such as the use of insulated cavity walls, double glazed sealed windows and insulated lofts. The energy consumption and thermal performance of two different types of house, an old and a new detached house are compared. Attention was focused on the living areas. The rate of air in-flow as determined by tracer gas, the air velocity and temperature distribution at two levels of 0.15 and 1.2 m were measured. The results show that in the new house the temperature difference between a seated person's head and ankle is more than 3 °C. This difference is increased when the central heating is switched on. In both houses the gap under the entrance door is large and contributes to a high internal air velocity. Despite the inadequacy of the installed air ventilator, the energy efficiency of the new house is demonstrated.     

Thermal performance analysis and economic evaluation of roof-integrated solar concrete collector

This paper examines the thermal performance of a roof-integrated solar concrete collector for reducing heat gain to a house and providing domestic hot water. The solar concrete collector is made of PVC pipes embedded in deck slab or concrete roof. No glazing on the top of the solar concrete collector or insulation at the back has been used as in conventional solar water heaters. To compare the energy saving, two test rooms of 2.3 m width, 2.5 m length and 2.5 m height were built. In the first room, the reinforced cement concrete (R.C.C.) slab was used as deck slab whereas the second room was equipped with a cement concrete solar collector. The experimental results showed that the cement concrete solar collector is extremely interesting as it can produce up to 40 l of hot water per day at water temperatures ranging from 40 to 50 °C. A mathematical model based on the conservation equations of energy is developed to predict the performance of the cement concrete solar collector. There is reasonable agreement from the comparison between measured data and predicted results. The economic analysis indicates that the payback period is rather fast.     

陶粒湿屋面隔热效果的测试研究

屋面作为建筑物与大自然的主要交汇面,是太阳光和热的主要承受面,也是降水的主要承受面。从陶粒湿屋面概念和隔热机理分析入手,在2007年7月23日至8月5日期间,对试验房和对比房室内外空气温度和各表面温度进行了实地测试,并对测试结果进行了整理分析。结果表明:由于陶粒的铺设,不仅使陶粒湿屋面建筑夏季室内热环境舒适性提高了,即陶粒湿屋面夏季具有明显的隔热降温作用。同时,还可以有效地减小夏季作用在屋面防水层上的温度振幅,延缓防水层的老化、延长使用寿命,减缓城市排污系统的压力,使建筑与自然环境相协调。     

Comparison of DOE-2 with temperature measurements in the Pala test houses

The predictions of version 2.1E of the DOE-2 program for building energy analysis have been compared with measurements in the Pala test houses near San Diego, CA. This work was part of the California Institute for Energy Efficiency ‘Alternatives to Compressor Cooling in California Transition Zones’ project in which DOE-2 was used for parametric analysis of cooling strategies that reduce peak electrical demand. To establish the validity of DOE-2 for this kind of analysis the program was compared with room air temperature measurements in a ‘low-mass’ house with conventional insulated stud wall construction and a ‘high-mass’ house with insulated concrete walls. To test different aspects of the DOE-2 calculation, four different unoccupied, unconditioned thermal configurations of these houses were considered: unshaded windows, shaded windows, white exterior surfaces, and forced night ventilation. In all cases DOE-2 agreed well with the air temperature measurements, with a mean deviation between simulation and measurement ranging from 0.2 to 1.0 K depending on configuration and type of house. Comparisons with inside surface temperature measurements also showed good agreement. Agreement between predictions and measurements improved when a more accurate calculation of foundation heat transfer was used, the ground surface temperature was calculated, and the normal 7-day ‘warm-up’ period in DOE-2 was extended to 11 days for the high-mass house.     

Application of passive cooling systems in the hot and humid climate: The case study of solar chimney and wetted roof in Thailand

The thermal performance of two passive cooling systems under hot and humid climate condition is experimentally investigated. The experimental results were obtained from a test cell and a controlled cell with identical walls but different roof configurations. The passive cooling systems applied to the test cell are solar chimney and water spraying on roof. The experimental results obtained from the test cell are compared with the closed and no passive cooling controlled cell. In addition, the significant of solar-induced ventilation by using a solar chimney is realized by utilizing a wind shield to reduce the effect of wind-induced ventilation resulting in low measured air velocities to the solar chimney and low computed value of coefficient of discharge. The derived coefficient of discharge of 0.4 is used to compute Air Changes rates per Hour (ACH). The ACHs with application of solar chimney solely are found to be in the range of 0.16–1.98. The studies of air temperature differences between the room and the solar chimney suggest amount of air flow rates for different periods in a year. The derived relationships show that the air flow rate during February–March is higher than during June–October by 16.7–53.7%. The experimental results show that application of the solar chimney in the test cell could maintain the room temperature at 31.0–36.5 °C, accounting for 1.0–3.5 °C lower than the ambient air and 1.0–1.3 °C lower than the controlled cell. However, to make the test cell's room temperature much lower than the ambient temperature and increase the flow rate of air due to the buoyancy, the application of water spraying on roof is recommended together with solar chimney. The application of the two systems in the hot and humid climate are discovered to sustain the room temperature of the test cell to be lower than the ambient air by 2.0–6.2 °C and lower than the controlled cell by 1.4–3.0 °C.     

黑球温度对房间热舒适性的影响分析

本文通过分析黑球温度计的工作原理,依据青藏铁路某被动太阳房试验数据研究,分析了太阳房室内黑球温度、空气温度和围护结构内表面温度之间的关系,提出用室内黑球温度和室内空气温度以及围护结构内表面温度的温差来评价房间热舒适性的方法和依据。     

A PV system enhanced the performance of roof solar collector

A simple PV ventilation system was used to enhance the performance of roof solar collector (RSC) for reducing heat gain and increasing the ventilation rate inside houses. The RSC is composed of CPAC Monier concrete tiles at the outer side, air gap and gypsum board at the house side. The PV system consists of one PV panel (27 Wp), a DC electrical fan (7.3 W) installed in the gap of RSC and a control unit.

Field testing results showed that the average temperature gradient between CPAC tiles, gypsum board and room was low, about 7°C, demonstrating a high heat gain reduction. The temperature of gypsum board was very close to the indoor temperature. The average PV powered air flow rate and the corresponding air change per unit RSC were about 100–250 m³/h and 3–8 ACH, respectively. Such rates are 2–4 times higher than those obtained with the natural ventilation induced by RSC. In addition, PV-powered RSC is an interesting option in the sense that it promotes solar energy and conserve energy.     

内保温住宅的户间传热温差

以目前新建住宅中较为普遍的钢筋混凝土内保温外墙、陶粒混凝土内墙结构的居住建筑为对象，建立房间不稳态传热的数学模型，通过数值求解，得出了四种典型房间，在北京地区供暖室外设计温度下，采用分室调节最低值（即停止采暖）时，其室温和邻室的户间传热温差及房间围护结构温度分布的变化规律，为进行住宅按户计量供暖设计热负荷的确定，提供了户间传热计算的依据，也为按户计量收费和建筑保温及防结霜研究提供了参考依据。     

外墙外保温系统对室内热环境的影响

采用对比试验的方法,建立采用外墙外保温系统的试验房间和不保温的对比试验房间,利用自动数据采集系统连续采集两房间不同部位的实时温湿度,分析外墙外保温系统的隔热保温性能。试验结果显示,外墙外保温系统具有优异的隔热保温性能。在相同的空调温控设定条件下,采用外保温的房间室内温度基本不受外界温度变化的影响。保温房间室内温度分布均匀。使用外墙外保温系统能营造良好的室内热环境。     

拉萨市建筑冬季热环境影响因素测试分析

为了掌握建筑朝向及外窗等因素对拉萨市冬季室内热环境的影响规律,为被动式太阳房的设计和采暖设计提供基础数据,笔者对该地区建筑冬季室内、外热环境进行了测试。结果表明:即使没有采暖系统,当地南向房间仍可基本达到人体热舒适中的温度要求;白天窗帘开启比窗帘关闭可提高南向房间日均室温1.1℃。即使南、北向房间分别采用单层、双层玻璃窗,当白天窗帘关闭时,前者日均室温也比后者高4.0℃;而当白天窗帘均开启时,前者更可高出7.4℃。北向房间双层玻璃窗全关闭与仅外扇关闭相比,日均室温可提高1.2℃。根据测试结果,建议增强北向外围护结构保温性能、增大南向房间透光面积,有利于改善当地建筑冬季室内热环境。     

One-year Measurement of Indoor Climate and Energy Consumption of Super-insulated Houses in a Mild Climate Region of Japan

Two super-insulated houses were constructed near Sendai City in accordance with the Canadian R-2000 manual (Canadian Home Builders' Assoc., 1987). Shelter performance, thermal environment, air quality and energy consumption of these two houses were investigated for one year. The two super-insulated houses were very airtight compared with other houses. The one-year measurement of room temperature and humidity for one super-insulated house showed that the daily mean temperature for the dining-living room and the master bedroom was 15°C-20°C during the winter and 22°C-28°C during the summer. Absolute humidity for these rooms was less than 5 g/kg (DA) during the winter. The indoor environment of the two super-insulated houses during the heating season was more thermally comfortable, compared with that of ordinary houses in Japan. During the summer, the indoor temperature in these two houses was stable during the day and did not decrease at night even if the outdoor air temperature dropped. The CO₂ concentration in these two houses was lower than that of other airtight houses due to continuous mechanical ventilation. The space heating energy consumption for one super-insulated house was less than that of ordinary houses in Tohoku District in which only the living-dining room was heated.     

A parametric study of Trombe walls for passive cooling of buildings

Air movement in a naturally-ventilated room can be induced through the use of a solar chimney or Trombe wall. In this work Trombe walls were studied for summer cooling of buildings. Ventilation rates resulting from natural cooling were predicted using the CFD (computational fluid dynamics) technique. The renoramlization group (RNG) k-ε turbulence model was used for the prediction of buoyant air flow and flow rate in enclosures with Trombe wall geometries. The CFD program was validated against experimental data from the literature and very good agreement between the prediction and measurement was achieved. The predicted ventilation rate increased with the wall temperature and heat gain. The effects of the distance between the wall and glazing, wall height, glazing type and wall insulation were also investigated. It was shown that in order to maximize the ventilation rate, the interior surface of a Trombe wall should be insulated for summer cooling. This would also prevent undesirable overheating of room air due to convection and radiation heat transfer from the wall.     

Energetisch und bauphysikalisch optimierte Sanierung eines Baudenkmals in Görlitz

Optimized energy saving rehabilitation of a baroque building monument. With the rehabilitation of the baroque building Handwerk 15 in Görlitz the authors achieved the energy efficiency class A+ under observance of all conditions from preservation of historic buildings and monuments, taking into account the environmental issues as well as durability and safety of the constructions in the house. The rehabilitation includes the internal thermal insulation of the historically valuable façade on the street side, the thermal insulation of the façade on the backyard side, the use of solar energy for hot water and for the support of heating especially in summer for heating the ground floor, a ventilation system with heat exchanger, the use of gray water generated from domestic processes such as laundry and bathing, and an underfloor heating for the ground floor with waste water as medium. The measurement results will be verified with numerical simulations (temperature, air, moisture transport in porous materials) of the separate building constructions and the technical components. The physical influence of the high building mass is quantified. The effects of the HVAC system on the historical building construction like for instance the timber beam floor will be investigated. Based on experiences about avoiding condensate and hoarfrost on inclined insulated glass together with a glass producing firm a new insulate glass with a special coating was developed.     

综合式太阳房辅助通风性能模拟

被动式太阳房是降低建筑能耗的有效方法之一。针对带有阳光间的综合式太阳房在夏季用于辅助通风时的通风性能进行了计算分析。通过对其阳光间建立传热模型,计算求解阳光间内空气的平均温度,从而求得太阳房辅助通风的通风量。结果表明,综合式太阳房的辅助通风性能可以满足一般住宅的新风要求,但对于有更高通风要求的建筑物则能力有限。文中的模拟计算,为今后对综合式太阳房进行深入的理论和实验研究提供了必要的理论基础。     

植被屋面隔热性能对比测试分析

在夏季自然气候条件下对植被屋面和无植被对比屋的面隔热性能进行了测试,通过分析测试数据,获得了屋面内表面温度分布特征、温度波的衰减性、屋面内表面与室外空气温度的关联性以及植被屋面各构造层的衰减性等相关隔热性能参数,并对其进行了对比评价分析,为其在实际工程应用提供了实验依据。     

Design considerations with ventilation-radiators: Comparisons to traditional two-panel radiators

Performance of heat emitters in a room is affected by their interaction with the ventilation system. A radiator gives more heat output with increased air flow along its heat transferring surface, and with increased thermal difference to surrounding air. Radiator heat output and comfort temperatures in a small one-person office were studied using different positions for the ventilation air inlet. In two of the four test cases the air inlet was placed between radiator panels to form ventilation-radiator systems. Investigations were made by CFD (Computational Fluid Dynamics) simulations, and included visualisation of thermal comfort conditions, as well as radiator heat output comparisons. The room model was exhaust-ventilated, with an air exchange rate equal to what is recommended for Swedish offices (7 l s⁻¹ per person) and cold infiltration air (−5 °C) typical of a winter day in Stockholm.Results showed that under these conditions ventilation-radiators were able to create a more stable thermal climate than the traditional radiator ventilation arrangements. In addition, when using ventilation-radiators the desired thermal climate could be achieved with a radiator surface temperature as much as 7.8 °C lower. It was concluded that in exhaust-ventilated office rooms, ventilation-radiators can provide energy and environmental savings.     

Temperature under a house with variable insulation

A calculation method of high accuracy is presented for the two-dimensional steady-state ground temperature under a long house. The thermal insulation thickness is arbitrarily variable along the ground surface. Explicit, iterative formulas with rapid convergency are given. The heat loss from the house and the ground surface temperature are given for three types of insulations. The method is available as a PC-program.