The reality of living in passive solar homes: A user-experience study

This paper presents a study of a user-experience survey about living in passive solar homes. It was carried out at the Energy Park located in the western part of Milton Keynes. The survey focuses on the reality of living in passive solar homes as perceived or experienced by the occupant. It is hoped that the findings would come to bear on strategic passive solar design decisions that would address the improvement of the well-being of the occupant.. The survey is aimed at assessing user satisfaction with the overall performance of their homes as well as a study of some of the problems that are believed to be common in passive solar housing.Results from the survey seem to indicate that the majority of those who buy passive solar homes are motivated to do so by a desire for thermal comfort at low cost. The building aesthetics is the second most important factor, showing that passive solar home lovers are also conscious of the quality of the architectural design. The overall performance of passive solar homes in this study, with regard to thermal and visual comfort, seems to be generally satisfactory. Statistical analysis showed some significant association between some important environmental design parameters.     

On the study of applications of solar thermal energy for mobile homes

A great deal of work has been done in the study of applications of solar thermal energy for conventional site-built houses; however, little effort has been directed to the study of these applications for mobile homes although they account virtually for a large portion of low cost single family homes. Mobile homes are different from the conventional home and building in configuration, structure, arrangement and cost. The concept and criteria of designing a solar space heating/cooling system for mobile homes differs somewhat from that of a conventional site-built house or building. The mobile home is a low-cost housing. The solar system developed for mobile homes should be really low in cost before it can appeal to the mobile home community. This paper presents the unique characteristics of mobile homes and their impacts on the design/selection of its solar space heating/cooling system and system for supplying domestic hot water. A typical model mobile home is selected for investigation of the solar system design for four representative climatic regions (cool, temperate, hot-humid and hot-arid) of this country. Economical feasibility study is also discussed. A low-cost solar collector is suggested and its estimated performance is presented.     

Development of a database of low energy homes around the world and analyses of their trends

This study aims to develop a database of low energy techniques for homes around the world, for use in systematically evaluating the low energy home in each region, where climate, culture and policy differ. First, a database was made for the purpose of the systemizing passive and active techniques. Data were input according to seven chapters and 155 items, and 66 homes in 17 nations have been recorded. Homes adopting super insulation, high airtightness and solar energy utilization are common in the each country. The thermal insulation performance of wall and window of the housing in Japan is somewhat inferior to that overseas. It was shown that exhaust heat recovery is rarely adopted in Japan and that the underground thermal energy utilization was seen in less than 10% of recorded homes. Second, recorded homes were categorized according to characteristics of adopted strategies, and the reduction rate of purchased energy versus the purchased energy for a typical home was calculated. This revealed the purchased energy reduction rate of homes with both solar heat utilization and photovoltaic power generation to be very high.     

Solar benefits for mass housing in South Africa

The South African Government intends to build one million houses and to electrify 2. 5 million homes in the next 5 years. Only once in a nation's lifetime does such an opportunity occur for solar and low-energy architecture to benefit all. Solar power, solar hot water and thermal design of housing present substantial savings to home owners and the nation. Legislation is presently emerging.     

Passive and active residential solar heating: A comparative economic analysis of select designs

This paper compares four passive solar heating concepts to a conventional air collector/rock storage system. Masonry (Trombe) and water walls are considered in the presence and absence of night insulation. The performance of optimally sized systems is evaluated on a state-by-state basis. The effects of low interest loans and National Energy Act (NBA) income tax credits are examined. With natural gas as the alternative fuel, the passive designs evaluated here offer more promise than the active system. This is true with or without inclusion of incentives, although either incentive option enhances economic performance. The passive designs evaluated in this paper are economically competitive against the electric resistance alternative in all but a few states. Moreover, on a life cycle cost basis, these designs are feasible today. Although the optimal solar fractions are generally low, passive designs offer the opportunity to incorporate solar heating into a new home at costs much less than their active counterparts. This is because there are no discernible fixed costs, thereby allowing a simple movement from zero to 100% solar when evaluating economic feasibility. When both active and passive design are shown to be cost competitive against alternative fuels, higher solar fractions will be associated with the active systems. This is principally due to the substantial fixed cost component of active systems, which forces one to achieve a given solar fraction before economic feasibility can be shown.     

Do the numbers stack up? Lessons from a zero carbon housing estate

Many countries are searching for ways to reduce the energy and carbon impact of housing. The terms net zero-energy home and net zero-carbon home have entered the policy lexicon, without clear definitions and without widespread understanding of the likely policy impact. Is the concept limited to bespoke architect driven buildings for specific green clients, or does it have relevance in the mainstream house building sector and for typical households? When we consider volume house building and contemporary lifestyles, what is the energy end-use reality of so called zero-energy homes? Can government policy instruments deliver housing estates that are thermally comfortable, energy efficient and powered by renewable energy?The Lochiel Park Green Village in South Australia represents a genuine attempt through government policy processes to create a suburb of (nearly) zero-energy homes in a near zero-carbon estate. The development includes 103 highly energy efficient homes of various sizes, all utilising solar thermal and solar photovoltaic sources, and built to stringent environmental urban design guidelines. The energy used and generated at each house is being monitored and analysed to extend our understanding of what happens when families bring their energy habits to near zero-energy homes. Appliance and equipment audits are conducted to extend our knowledge of the energy services utilised in contemporary digital-age lifestyles.This paper provides an insight into the quanta of energy using appliances and equipment that fill our homes and satisfy our ever-growing needs. The paper presents key results from the first two years of monitoring for the initial tranche of houses, demonstrating that although significant reductions in operating energy use have been achieved, few households have reached a net zero energy standard. The research highlights the extent to which our choice of energy systems and our individual behaviour affect the total annual energy use. The energy end-use and energy generation results are examined to identify the contribution of near zero-energy homes to the twin policy challenges of anthropogenic climate change and peak power demand. Using empirical evidence from extensive monitoring, this paper throws new light on the energy use of actual families in contemporary near zero-energy homes.     

Altering existing buildings in the UK

The profiles of both existing housing and existing public and commercial buildings show that many have very poor thermal efficiency. The UK housing stock is replaced at a low rate of about 1% a year, so to cut energy use it is essential to address the challenges of existing buildings. This will involve reducing energy demand through passive measures such as retrofitted insulation, replacement of windows and proper airtightness, while ensuring adequate ventilation. Active measures include upgrading improved boilers and adding locally produced energy from wind, biomass, solar power and other sources. The introduction of Display Energy Certificates will increase energy awareness but there will also need to be a programme of increased demolition for the worst-performing homes. In addition, buildings will need to be adapted to cope with worse weather, higher temperatures and increased flood risk as climate change takes effect. Overheating, rather than excessive cold, is set to become a growing problem for householders and employees in existing UK buildings.     

Effect of financial and fiscal incentives on the effective capital cost of solar energy technologies to the user

Development and dissemination of solar energy technologies in India has been aided by a variety of policy and support measures. One of the promotional measures is the provision of financial and fiscal incentives such as capital subsidy, low interest loan and accelerated depreciation related income tax benefits to the users on the purchase of solar energy technologies. In this study an attempt has been made to determine the effective capital cost of solar energy technologies to the user with the provision of financial and/or fiscal incentives. Results of exemplifying calculations for a domestic and an industrial solar water heating system, a solar home lighting system and a solar drying system have been presented and discussed.     

Systematic comprehensive techno-economic assessment of solar cooling technologies using location-specific climate data

A methodology for assessing solar cooling technologies is proposed. The method takes into account location specific boundary conditions such as the cooling demand time series, solar resource availability, climatic conditions, component cost and component performance characteristics. This methodology evaluates the techno-economic performance of the solar collector/chiller system. We demonstrate the method by systematic evaluation of 25 feasible combinations of solar energy collection and cooling technologies. The comparison includes solar thermal and solar electric cooling options and is extended to solar cooling through concentrated solar power plants. Solar cooling technologies are compared on an economic and overall system efficiency perspective. This analysis has implication for the importance of solar load fraction and storage size in the design of solar cooling systems. We also stress the importance of studying the relation between cooling demand and solar resource availability, it was found that overlooking this relation might lead to overestimations of the potential of a solar cooling system in the range of 22% to over 100% of the actual potential.     

Move it! How an electric contest motivates households to shift their load profile

Photovoltaic systems generate electricity around noon, when many homes are empty. Conversely, residential electricity demand peaks in the evening, when production from solar sources is impossible. Based on a randomized control trial, we assess the effectiveness of alternative demand response measures aimed at mitigating these imbalances. More precisely, through information feedback and financial rewards, we encourage households to shift electricity consumption toward the middle of the day. Using a difference-in-differences approach, we find that financial incentives induce a significant increase of the relative consumption during the period of the day when most solar radiation takes place. Information feedback, however, pushes households to decrease overall consumption, but induces no load shifting.     

The sun rises in the east (of Africa): A comparison of the development and status of solar energy markets in Kenya and Tanzania

This paper describes, compares and analyses the historical development and current status of Kenya's and Tanzania's emerging solar energy markets. The analysis is based on an extensive literature survey and 25 in-depth personal interviews with experts on the East African solar power market. Kenya's solar market is found to be one of the world's leading markets for off-grid solar uses, with a current installed capacity of over 10 MWp and more than 320,000 solar home systems. Having developed much later than the Kenyan market, Tanzania’s market still remains smaller than its neighbour’s, with an installed capacity of around 4 MWp and at least 40,000 solar home systems, but is in the process of catching up. In addition to solar home systems, other applications of solar energy technologies, such as in social institutions, telecoms and tourism, are covered. Major differences and similarities between the Kenyan and Tanzanian solar markets are identified and reasons for these are analysed. Initial policy implications regarding the regulation and promotion of solar energy in East Africa suggest that awareness, availability and affordability are major drivers that all need to be present to enable the widespread adoption of off-grid solar technologies in emerging markets.     

Towards zero energy homes down under

The concept of net zero energy and zero emission home has been a goal for those involved in the sustainable building industry. It is now becoming a reality in many parts of the world with an integrated approach of passive design, energy efficient appliances and local renewable generation. The paper describes the activities in Australia focussing on reducing energy use from the housing sector. It describes the regulatory approach of energy performance for housing which involves developing a house energy rating tool covering the building envelope as well as major energy consuming appliances. It also describes the implementation process which comprises gradually more stringent regulations coupled with financial inducements.The paper describes a world leading new Australian housing development where net zero energy homes are being built and enjoyed. It tells the story of how this outcome is being achieved starting with the planning process and developing environmental guidelines. The paper describes the innovations being used in order to achieve net zero energy homes and reports on energy monitoring results and feedback from householders.     

Trends in observable passive solar design strategies for existing homes in the U.S.

Passive design strategies are among the most cost-effective methods to reduce energy consumption in buildings. However, the prevalence of these strategies in existing U.S. homes is not well understood. To help address this issue, this research evaluated a nationally-representative sample of 1000 existing homes distributed geographically across the U.S. Using satellite images, each building was evaluated for three passive design strategies: orientation, roof color, and level of shading. Several statistically significant regional trends were identified. For example, existing homes in the High Plains, Ohio Valley, Northwest, and Southern regions show a statistically significant trend towards orientation in the East–West direction, an effective passive design strategy. Less intuitively, in terms of what would seem to be optimal passive design, buildings in the High Plains and Ohio Valley generally have lighter roof colors than buildings in the warmer Southwest region. At the national level, no statistically significant trends were found towards the passive design strategies evaluated. These trends give us no reason to believe they were a major consideration in the design of existing homes. Policy measures and education may be required to take advantage of the opportunity for cost-effective energy savings through more widespread passive solar design.     

Technologies to achieve demand reduction and microgeneration in buildings

Buildings account for almost half of UK carbon dioxide emissions, and energy demand in buildings continues to grow. In the context of economic growth, population growth, increasing demand for homes and commercial floor space, and increasing demand for energy services, energy use and probably carbon emissions look set to continue to increase unless there is significant change. This paper outlines enabling technologies that may permit a step-change reduction in energy demand from buildings through the application of next-generation information metering and control, energy-efficiency products and microgeneration. It covers both residential and non-residential buildings. This wide approach has been adopted because technologies and trends tend to migrate from one building sector to another, as, for example, IT has moved from offices into homes and lighting trends from offices and retail into homes. It covers technologies that can be used in new build or major refurbishment. Much of the need for change involves the better use of known technology, and some involves changing behaviour. Some behaviour depends on new technologies such as metering. Understanding how technological innovations are taken up (e.g. stock turnover issues, as well as how technical change occurs) and the economics of new technologies is as important as the technologies themselves.     

Feasibility study on the relation between housing density and solar accessibility and potential uses

This paper aims to address how the solar potential and accessibility of urban housing affects solar energy performance and architectural design. Several simulations were conducted to investigate the relationships between climate conditions and active and passive solar potential by manipulating density-related design factors, including typology, layout, site coverage, floor area ratio (FAR), and number of storeys. The research process consisted of two scenarios: (1) three distinct urban city areas were compared to show the range of solar potential by housing density variation and, (2) 24 generic models of low-rise, mid-rise and high rise housing were analyzed according to changes in density related factors. This research provides a methodology for evaluating solar potential in urban scale and the relationship between housing density and urban design using simulation programs. Based on the outcomes of this research, solar accessibility, the amount of solar irradiation that reaches a building façade and roof, is shown to be related to housing density. The comparison scenarios provide insight into how density and density related factors impact solar potential and, as a consequence, suggest ways to optimize the capacity for solar collection during the initial urban planning phase.     

The development of the domus-Solarhome

This paper describes the development of a German passive solar house concept, the worldwide known Domus-Solarhome. Today it is the most well-known passive solar concept for single family houses in Germany. Five years' experience, thermal performance and operating data of a prototype, since 1980 known as the Semm's Residence in Kiel, enabled the development of the ‘Domus’ with design criteria especially for the climate of mid-Europe. The most important design criteria are discussed. The author explains the way into the market. More than 50 Domus-Solarhomes are already constructed in various parts of Germany. To sell those homes the Domus-Solarhaus Inc. was founded. Domus developed the first passive solar house for middle and low income brackets.     

Wind power systems for zero net energy housing in the United States

This work investigates the feasibility of renewable energy housing development in the U.S. using wind power and solar thermal systems to attain zero net energy consumption. The over all objective was to determine how the wind power and solar thermal system designs and economics differ with various climates, wind and solar resources, energy prices, and state incentives, such as net-metering. Five U.S. cities, one in each of the five climate zones, were selected for this study based on their potential for wind power. A zero net energy housing design tool was developed in order to analyze and compare various system designs. The energy performance and economics of the designs were compared for various sizes of housing development, for seven turbine models, and selected heating systems. The results suggest that while there are some economical options for wind powered zero net energy housing developments, they are generally more expensive (except in the warmest climate zone) than housing with natural gas heating. In all of the cases, the economies of scale for large-scale wind turbines gave more of an economic advantage than net-metering programs gave small- and medium-scale wind turbines.     

Solar-based rural electrification policy design: The Renewable Energy Service Company (RESCO) model in Fiji

Solar photovoltaic technologies have for some time been promoted as a cost effective means of rural electrification in developing countries. However, institutional structures resulting in poor maintenance have adversely affected the sustainability of past solar projects. In Fiji, the Renewable Energy Service Company (RESCO) program is the latest attempt to promote solar-based rural electrification in a fee-for-service model, aiming to remove the high upfront capital costs associated with solar technologies and using a public–private sector partnership for maintenance. This paper assesses the program using survey and interview data. Major flaws are identified, relating to incorrect treatment of principal–agent problems, information asymmetries, motivational problems, and resourcing of government agencies. General lessons for fee-for-service solar home system models emerge, including that incentives for stakeholders must take centre stage in designing and administering such programs, and that active government support and ownership are required to make programs sustainable.     

夏热冬冷地区小城镇被动式太阳房的设计

论述了小城镇被动式太阳房的基本原理,提出了被动式太阳房利用太阳能的几种形式及设计方案。在夏热冬冷地区小城镇住宅中利用太阳能是一种节能而环保的技术。     

Recommendation on modelling of solar energy incident on a building envelope

It is important to know how to design a building to meet seasonally varying energy needs. In high latitude countries in winter the demand for space heating is high and a building envelope should receive maximum incident solar energy. On the other hand, in summer, walls and roofs exposed to incident solar radiation usually require shading to avoid too much solar gain. Data on solar energy availability are crucial for good building design. However, it is important how the availability of solar radiation is determined. An important aim of the paper presented is to give some results of a comparative analysis of two basic sky models, isotropic: Hottel–Woertz–Liu–Jordan and anisotropic: the HDKR, Hay–Davies–Klucher–Reindl, to recommend one of these models for determination of solar energy availability on a building envelope and to formulate the energy balance of a building. Differences between results obtained from both models increase with the slope of exposed surfaces. The biggest differences (12–15%) are evident for vertical south surfaces, especially in summer. The simplified isotropic sky model is not recommended for evaluation of solar radiation availability on the building envelope. Underestimation of solar gains can lead to the selection of an unsuitable concept and construction of a building and result in poor indoor thermal comfort, i.e. overheating of rooms in summer.