Building leakage,infiltration, and energy performance analyses for Finnish detached houses

This study focuses on the relation between the airtightness of a building envelope, infiltration, and energy use of a typical modern Finnish detached house in the cold climate of Finland. The study is conducted with an empirically tested dynamic IDA-ICE simulation model of a detached house. The effect of several factors, such as Finnish climate and wind conditions, balance of ventilation system and leakage distribution, on infiltration was studied and a simple adapted model for the rough estimation of annual infiltration in Finnish detached houses was determined from the numerical simulation results. The energy impact of infiltration is also studied, taking into account the infiltration heat recovery effect. According to the results, infiltration causes about 15–30% of the energy use of space heating including ventilation in the typical Finnish detached house. The average infiltration rate and heat energy use increase almost linearly with the building leakage rate n₅₀. Finland can be roughly divided into two zones based on the average infiltration rate of detached houses, for which stack-induced infiltration is typically dominant, regardless of the climate zone. The infiltration heat recovery effect is minor in the studied detached house.     

Heat transfer model of hot-wall Kang based on the non-uniform Kang surface temperature in Chinese rural residences

Chinese Kangs are widely used for home space heating in rural residences. However, the energy efficiency of a traditional Kang is less than 20%. Thus, the hot-wall Kang is gradually becoming popular in Jilin, Heilongjiang and Inner Mongolia of China because of its higher energy efficiency, comfortable indoor thermal environment and flexibility of application. The hot-wall Kang has three operation modes. The heat transfer model of Kang in previous studies was developed based on the three assumptions, which include the uniform Kang surface temperature, the neglect of the radiation effect of gas and the thermal storage of ash soil layer. However, the model of hot-wall Kang in this paper was improved with respect to the three assumptions, which were discussed in this paper. Then, the model was validated by experiments and applied to optimize the thermal performance of the hot-wall Kang. The results showed that the simulation results were in good agreement with the measurement results. Furthermore, based on the verified model, the better thickness and material of the cover board were found to be 0.06 m and foam concrete, respectively.     

中国被动房外围护系统研究——以寒冷、严寒气候区被动房项目为例

德国的被动房是目前世界公认的具有超低能耗、超低碳排放量、超高室内舒适度等特点的建筑技术体系。德国的气候特征与中国华北地区的气候特征具有相似性,因此,研究并建造被动房对于我国建筑节能工作的发展具有重大的意义。外围护系统作为被动房设计的重点要素,对建筑的节能效率有重大的影响。以寒冷、严寒气候区的被动房项目为例,对被动房外围护系统进行分析与阐述,并以秦皇岛"在水一方"被动式住宅示范项目为例,进行能耗模拟与对比分析。提出适合我国寒冷、严寒气候区气候特点的被动式超低能耗建筑外围护系统的设计策略。     

Experimental study of a solar-assisted ground-coupled heat pump system with solar seasonal thermal storage in severe cold areas

This paper presents the experimental study of a solar-assisted ground-coupled heat pump system (SAGCHPS) with solar seasonal thermal storage installed in a detached house in Harbin. The solar seasonal thermal storage was conducted throughout the non-heating seasons. In summer, the soil was used as the heat sink to cool the building directly. In winter, the solar energy was used as a priority, and the building was heated by a ground-coupled heat pump (GCHP) and solar collectors alternately. The results show that the system can meet the heating-cooling energy needs of the building. In the heating mode, the heat directly supplied by solar collectors accounted for 49.7% of the total heating output, and the average coefficient of performance (COP) of the heat pump and the system were 4.29 and 6.55, respectively. In the cooling mode, the COP of the system reached 21.35, as the heat pump was not necessary to be started. After a year of operation, the heat extracted from the soil by the heat pump accounted for 75.5% of the heat stored by solar seasonal thermal storage. The excess heat raised the soil temperature to a higher level, which was favorable for increasing the COP of the heat pump.     

Modelling floor heating systems using a validated two-dimensional ground-coupled numerical model

This paper presents a two-dimensional simulation model of the heat losses and temperatures in a slab on grade floor with floor heating which is able to dynamically model the floor heating system. The aim of this work is to be able to model, in detail, the influence from the floor construction and foundation on the performance of the floor heating system. The ground-coupled floor heating model is validated against measurements from a single-family house. The simulation model is coupled to a whole-building energy simulation model with inclusion of heat losses and heat supply to the room above the floor. This model can be used to design energy efficient houses with floor heating focusing on the heat loss through the floor construction and foundation. It is found that it is important to model the dynamics of the floor heating system to find the correct heat loss to the ground, and further, that the foundation has a large impact on the energy consumption of buildings heated by floor heating. Consequently, this detail should be in focus when designing houses with floor heating.     

Chinese kang as a domestic heating system in rural northern China—A review

The Chinese kang is an ancient integrated home system for cooking, sleeping, domestic heating and ventilation. It is still widely used today in nearly 85% of rural homes in northern China. In 2004, there were 67 million kangs used by 175 million people. Existing kang designs are mostly based on the intuition and accumulation of craftsman experience. There is a trend that Chinese kang is gradually replaced by bed and coal-burning radiators, domestic heating stoves, etc. using commercial energy. As rural building heating constitutes 25% of total building energy consumption in China, we consider that the transition and new technologies for rural home heating in northern China is crucial for managing future building energy consumption in China. This paper reviews the basic heat transfer and airflow principles of Chinese kang, as well as describing the traditional grounded kang and the relatively new elevated kang. The thermal performance of the kang is shown by data from literature and field surveys. The future of Chinese kang and research needs is also briefly discussed. There is also a need for scientific study in addition to experience accumulation, to form basis for engineering design.     

The performance of a well insulated house heated by an air-water heat pump

This paper describes the performance of a highly insulated house operated under simulated occupancy and heated by an air-water heat pump during 1978–80. The house, which was one of four BRE low energy house laboratories, was heated continuously to 20°C.

Although underfloor heating coils were employed. (in order to provide a low condensing temperature for the heat pump) the control of internal temperatures was largely satisfactory being within ± 2°C of the mean value on over 85% of occasions.

The seasonal coefficient of performance of the heat pump for space and hot water heating was 2.3 which in primary energy terms corresponds to a natural gas boiler of about 70% efficiency. The heat demand of the dwelling at ?1°C was 3.8 kW which was close to the expected value and the heat pump required backup heating only during some defrosts. The backup heating system was used in the true supplementary mode only on 2 days during the winter of 1978/79.     

Method for achieving hydraulic balance in typical Chinese building heating systems by managing differential pressure and flow

Hydraulic unbalance is a common problem in Chinese district heating (DH) systems. Hydraulic unbalance has resulted in poor flow distribution among heating branches and overheating of apartments. Studies show that nearly 30% of the total heat supply is being wasted in Chinese DH systems due to a lack of pressure and flow control. This study investigated using pre-set radiator valves combined with differential pressure (DP) controllers to achieve hydraulic balance in building distribution systems, and consequently save energy and reduce the emissions. We considered a multi-storey building modelled in the IDA-ICE software, along with a self-developed mathematical hydraulic model to simulate its heat performance and hydraulic performance with various control scenarios. In contrast to the situation with no pressure or flow control, this solution achieves the required flow distribution and close-to-design room temperatures, as well as 16% heat savings, 74% pump electricity savings, and proper cooling of supply water. The energy consumption savings would therefore have positive environmental impacts, and be reflected in seasonal reductions of 2.1 kg/m² CO₂, 0.02 kg/m² SO₂, and 0.01 kg/m² NO_x for 3rd step energy efficiency buildings in Beijing.     

1st Environmental conference of Thessaly region, 8–10 September 2012, Hotel Skiathos Palace,Koukounaries, Skiathos Island,Greece

This study was conducted with the aim to assess the potential performance of a photovoltaic thermal mechanical ventilation heat recovery (PV/T MVHR) system. The device is currently considered for the application to the Z-en house project undertaken by Scottish homebuilder. The house’s whole energy demand was calibrated based on the UK Government’s standard assessment procedure for energy rating of dwellings, while the PV/T performance was estimated using an ‘EESLISM’ energy and environmental design simulation tool developed by Kogakuin University. This study concluded that PV generates heat, which makes the fresh air running under the PV roof 10–15?°C warmer than the outside temperature even during the Scottish winter and this warm air extracted from roof-integrated PV modules can be used to help reduce the domestic space-heating demand. Thus, the building-integrated PV/T MVHR system was considered as one of the effective means to assist the net zero energy operation of housing in cool and cold climates, whose dominant domestic energy comsumption derives from space heating.     

上海地区空气源热泵地板采暖系统应用研究

冬季采暖问题在夏热冬冷地区日趋得到重视，而地板采暖系统以其舒适性的优势得到越来越多的关注：其中以空气源热泵作为冷热源的系统既解决了夏季空调的需要，又可在冬季提供舒适的温水地板采暖，近几年在华北等地区得到推广应用。为了考察夏热冬冷地区的空气源热泵地板采暖的技术经济可行性，积累其运行的技术数据，本实验研究以上海地区的一栋独立别墅住宅为对象，经过采暖期中一个月的实测，系统地测得了空气源热泵地板采暖的特性参数和运行能耗数据，把握了空气源热泵地板采暖的运行规律。本文基于实测数据，对上海地区将空气源热泵用于地板采暖系统进行技术经济性分析。     

寒区隧道地源热泵型供热系统取热段温度场解析

为解决寒区隧道冻害问题,将地源热泵型供热系统应用于内蒙古博牙高速林场隧道中。供热系统由取热段、加热段、热泵和分、集水管路组成,可用于隧道洞口段衬砌和排水系统加热。取热段位于隧道中部,获取围岩中的地热能。隧道取热段温度场由热交换管外围岩温度场和热交换管内流体温度场两部分组成。建立考虑衬砌结构和热源的隧道取热段热交换管外围岩传热模型,利用叠加原理、拉普拉斯变换和积分变换相结合的方法获得取热段温度场解析解。基于能量守恒原理建立热交换管内流体传热模型,根据热交换管外围岩温度场,利用迭代法计算热交换管的出口温度。采用反分析的方法确定试验段围岩的综合热物性参数,将理论解与现场试验数据对比分析,其精度满足工程要求。取热段温度场理论解为系统的设计提供理论指导。     

Evaluation of energy-related and economic aspects of heating a family house with dendromass in the north-east of Poland

This paper presents an evaluation of energy-related and economic aspects of production of thermal energy to heat a family house with wood briquette. The object of the study was a detached house with an area of 247 m², situated in Olsztyn, in the north-east of Poland. The study lasted three years, from October 2006 to September 2009. The highest monthly consumption of wood briquette for thermal energy production: heating water for the central heating system and hot utility water production were recorded in January (1052–1333 kg/month). The average annual briquette consumption ranged from 6.36 to 6.72 t/year. With the mean lower heating value of briquette of 17.99 GJ/t, the mean consumption of energy in the fuel ranged from 114 to 121 GJ/year. The annual cost of heat production for a family house with briquette as fuel ranged from €572 to €651, during the 2006/2007 and 2008/2009 seasons, respectively. It would have been cheaper by €187–228 year^?1 to heat the house with seasoned willow chips, whereas using alternative fuels, such as hard coal (fraction 0.5–2.5 cm) oak pellets, natural gas and heating oil would have increased the cost of heat production. If the last of those fuels had been used, it would have increased the cost 3.5-fold as compared with wood briquette.     

Exergy efficiency analysis in buildings climatized with LiCl–H2O solar cooling systems that use swimming pools as heat sinks

Solar cooling is emerging as one of the most interesting applications in the harnessing of solar energy for alternative uses. Current devices can effectively control the climates of small buildings while addressing the issues associated with the excessive thermal energy captured during the summer months. This article presents an exergy analysis of buildings with solar thermal systems used for Domestic Hot Water (DHW) production and heating and cooling support. The cooling system analyzed is a LiCl–H₂O thermally driven heat pump with integral energy storage that uses outdoor swimming pools as heat sink. All subsystems were integrated into the model and considered as a single energy system, and data from installations in three different locations were used. The influences of the heating and cooling demand ratios and the dead state and house temperatures were analyzed. Further, the use of dissipated energy was analyzed, demonstrating that the proposed method facilitates the realistic study of these systems and provides useful analytical tools for improving the overall exergy performance. The energy delivered for heating, cooling and DHW production strongly influences global performance, suggesting that the appropriate sizing of each system is a priority.     

Design optimisation for a low energy home in Sydney

A simple model for a detached house in Sydney is optimised using a building energy simulation program to reduce the annual heating and cooling requirement to the point where a heating and cooling system is no longer necessary. A net present cost analysis, including the construction cost, the HVAC capital cost, and the electricity cost for space heating and cooling, is used to conduct the optimisation. The insulation thickness of the walls and roof, the window type, the thickness of an internal thermal mass wall, and the night ventilation air change rate were varied in the optimisation. Results for the best performing optimisation cases are presented and compared with the net present cost for a similar house, designed to meet the BASIX energy efficiency requirement for New South Wales. The best performing optimisation cases are shown to have a lower net present cost than the equivalent BASIX compliant house. With a view towards creating an operationally zero energy house, an optimisation case with a very low space energy requirement is selected and a photovoltaic system is sized to cover the remaining household electricity consumption over the course of a year.     

Renewable energy for passive house heating: Model of the active solar heating system

The large windows on the south-oriented façade of a passive house strongly contribute to building space heating. These windows constitute the passive solar heating system. This paper studies the active heating system of a passive house, which includes the following sub-systems: (1) solar thermal collectors, (2) a water storage tank, (3) a secondary water circuit, (4) a domestic hot water preparation system and (5) an air ventilation and heating system. Models for all sub-systems are presented. The integrated model was implemented to Pirmasens Passive House (Rhineland Palatinate, Germany). The active solar heating system provides a smaller amount of heat than the heat provided by the passive solar heating system. Almost all the solar energy collected is not used for space heating but to domestic hot water (DHW) preparation. However, there is still a need for the classical water heater to operate all over the year. Almost all space heating thermal load is covered by using the classical air heater that operates mainly during the nights from November to April. The solar fraction lies between 0.180 in February and 0.679 in October, with a yearly average of 0.446. The study reveals that on a yearly basis it is more advantageous to use vertical south-oriented solar collectors instead of roof placed collectors.     

适用于既有住宅计量供暖的串联热量表

由于我国既有住宅的垂直单管顺流式供暖系统不是闭环系统,因此只能采用热分配表来实现计量供暖,但热分配表存在着技术问题,难于在我国既有住宅计量供暖中推广应用。在分析现有热量计量装置存在的问题基础上,提出适用于垂直单管顺流式系统计量供暖的串联热量表,对其安装方式、计量原理及特点进行了研究。串联热量表不受散热器装饰方式及人为因素的影响,计量精度高,实用性高,经济性优。     

火墙式火炕炕体传热特征及内部烟气流动特性实验研究

火炕是目前我国北方地区解决农村采暖问题、优化能源消耗结构和提高室内热环境的一种有效方式。本文以火墙式火炕为研究对象,采用实验研究的方法,分析了火炕内部烟气温度分布、烟气物理性质、烟气流动特性,以及烟气和火炕本体热量分布,为火墙式火炕的进一步优化设计提供了依据,同时也为低流速下烟气流动换热的研究提供了参考。实验结果表明,火炕内部烟气温度主要分上、下两层,烟气质量流速维持在0.05～0.065kg/s,烟气所带热量的60%～80%传给了炕体本身,炕本体效率可高达80.5%。存在的问题是排烟损失和通过火墙正下方地面的热量损失较多,火墙式火炕的结构有待于进一步的优化。     

Developing a passive house with a double-skin envelope based on energy and airflow performance

This research originated from an interest in developing products with a holistic and interdisciplinary systems engineering approach, toward fostering sustainability. A comprehensive method which helps designers make better decisions in the earliest design stage was applied for conceptual model development and comparison. The study developed a new-design passive house with a double-skin envelope that delivers better energy consumption performance for heating and cooling relative to a conventional reference house, while achieving comfort-level indoor temperatures. A single-façade reference house was designed with the identical geometry, material and conditions of the new house living quarters, in order to demonstrate the new house performance using a valid comparison. The new house and reference house were simulated cases and were not calibrated by actual models. The energy simulations demonstrated that the heating and cooling demands of the new house were 19.1% and 18.8% lower than those of the reference house, respectively. Furthermore, fluid dynamics behavior of the air inside the double-skin envelope was analyzed to demonstrate the airflow’s contribution to the energy performance. Computational fluid dynamics simulations revealed that turbulent airflow in the underground space on summer day increased heat transfer, and laminar airflow in the double-skin roof on winter night decreased such transfer.     

石蜡蓄热太阳能炕在北方农村住宅中的应用

本文针对北方农村地区的生活习惯设计了一套采用石蜡蓄热的太阳能采暖炕系统,不仅很好的利用太阳能这种清洁能源解决了炕的采暖问题,还可以在夏季提供部分生活热水。该太阳能炕系统中封装的石蜡由于其良好相变特性和较高的相变潜热,冬季供暖时段白天可在太阳能炕中续存一定的热量,晚上利用相变潜热释放的热量有效保证炕面温度,达到节能和提高舒适性的目的。对实际搭建的太阳能炕系统进行四个连续周期的测量表明,太阳辐照良好的情况下太阳能炕面平均温度可保证30~40℃的人体舒适性温度,具有很好的实际使用价值。     

Parameter identification and model based predictive control of temperature inside a house

HVAC (Heating, Ventilation and Air Conditioning) systems used for heating or cooling buildings, consume a considerable amount of energy. To optimize the energy consumption, the behavior of occupants must be changed. This can be achieved by providing information and suggestions to occupants. A first step is developing of a less expensive and non-invasive measurement system and metering of the electricity and heat consumed. Based on collected experimental data, it can identify the parameters of a thermal model of the house. The model obtained will be used to simulate different aspects that can help to reduce the energy consumption. This paper presents a simple solution for thermal modeling of a house which includes experimental identification of the model's parameters. Such data are used to simulate the thermal behavior of the house and to obtain solutions to reduce energy consumption. In simulation, the control of the thermal system is performed using a model based predictive control algorithm.