Evaluation of a solar thermal system using building louvre shading devices

External louvres are increasingly used to provide solar protection for building glazed surfaces. The integration of collectors into the external louvres of buildings offers a means of reducing system cost as well as providing architects with more freedom to integrate the technology into their designs. This work concerns the modification of existing louvre designs to integrate a solar collector in the shading device. The evaluation of a thermal solar system for water heating is assessed in this paper. A numerical model for the integrated solar collector was developed for different configurations and the collector efficiency is quantified for each configuration. System thermal performance was obtained for the climatic conditions of Lisbon (Portugal) and Tenerife (Spain). Economic and environmental viability of the system is assessed.     

An empirical validation of the daylighting algorithms and associated interactions in building energy simulation programs using various shading devices and windows

Empirical validation of building energy simulation programs is an important technique in examining the effectiveness and accuracies of implemented algorithms. In recent years, daylighting algorithms incorporated in building energy simulation programs have become increasingly sophisticated in their abilities to predict the illuminance, light power reductions, and the associated thermal load interactions. The focus of this study was to examine measured and simulated light levels in an actual building constructed for research purposes. Daylighting models were constructed in EnergyPlus and DOE-2.1E and the predicted illuminance and light power were compared with measurements; an assessment of heating and cooling interactions using a variable-air-volume reheat (VAVRH) system was also performed by analyzing reheat coil powers for the VAV boxes. The average differences from EnergyPlus for reference point daylight illuminance, light power, and reheat coil power predictions were within 119.2%, 16.9%, and 17.3%, respectively. DOE-2.1E predicted reference point daylight illuminances were within 114.1%, light powers were within 26.3%, and reheat coil power were within 25.4%.     

Assessment of energy savings from the revised building energy code of Thailand

The government of Thailand legislated an Energy Conservation Promotion Act (ECP Act) in 1992 and set bye-laws that identify designated buildings (DBs) and detail mandatory requirements for energy conservation for DBs in 1995. An Energy Conservation Promotion Fund (ENCON Fund) was also created to fund energy audits on 1900 DBs. Recently the requirements and procedures for energy conservation in buildings have been revised where system performance requirements for building envelope, lighting, air-conditioning, and hot water generation are adopted. Moreover, the new building energy code (BEC) distinguishes different categories of DBs, provides credit for use of solar energy, and introduces a new option of whole building energy compliance. The authors develop building models from data obtained from energy audit reports and use them to estimate savings on energy and peak demand from future new buildings using forecasted energy and peak demand data from the Load Forecast Subcommittee, a panel tasked to forecast future electric load of Thailand. From a modest level of energy saving in the first year that the code is expected to be enforced, the level of saving rise to over 10% and 20% annually of requirement of target buildings in 6 and 12 years respectively.     

Effect of building regulation on energy consumption in residential buildings in Korea

According to the International Energy Agency (IEA), the energy demand for the building sector constituted about 25.3% of the final energy use in South Korea. The energy demand for residential buildings counts for 50.3% of the building sector and has also increased by 2.9 percent every year. The Korean government has shifted focus and is now promoting energy efficiency within the building sector and has set long-term energy conservation goals.Despite these efforts to minimize building energy, the Korean government has changed the building regulation to allow remodeling of the balcony space as a living space. Remodeling the balcony space to become an indoor space means that a buffer space for the outdoor environment is lost, causing thermal discomfort and discomfort glare and moreover, increasing the heating and cooling energy demand in residential buildings. Also, it results in an increase in building energy demand in South Korea.In this study, the effect of the alteration of balcony space on the indoor thermal environment and the heating and cooling energy demand of residential buildings in Korea were investigated by field measurement and simulation. From the measurement results, the indoor temperature of the condition without a balcony was 0.8 °C lower than that with a balcony. The heating and cooling load of the unit without the balcony space was 39% and 22% higher, respectively, than that of the unit with the balcony space. This increase results in considerable energy loss in the national scale and the ratio will be 0.3% of the final energy use in Korea. Also, it represents about 1.3% of the final energy use within the building sector of Korea.     

How energy efficiency fails in the building industry

This paper examines how energy efficiency fails in the building industry based on many years of research into the integration of energy efficiency in the construction of buildings and sustainable architecture in Norway. It argues that energy-efficient construction has been seriously restrained by three interrelated problems: (1) deficiencies in public policy to stimulate energy efficiency, (2) limited governmental efforts to regulate the building industry, and (3) a conservative building industry. The paper concludes that innovation and implementation of new, energy-efficient technologies in the building industry requires new policies, better regulations and reformed practices in the industry itself.     

Evaluation of the impact of the surrounding urban morphology on building energy consumption

Empirical models of minimum (T_min), average (T_avg) and maximum (T_max) air temperature for Singapore estate have been developed and validated based on a long-tem field measurement. There are three major urban elements, which influence the urban temperature at the local scale. Essentially, they are buildings, greenery and pavement. Other related parameters identified for the study, such as green plot ratio (GnPR), sky view factor (SVF), surrounding building density, the wall surface area, pavement area, albedo are also evaluated to give a better understanding on the likely impact of the modified urban morphology on energy consumption.The objective of this research is to assess and to compare how the air temperature variation of urban condition can affect the building energy consumption in tropical climate of Singapore. In order to achieve this goal, a series of numerical calculation and building simulation are utilized. A total of 32 cases, considering different urban morphologies, are identified and evaluated to give better a understanding on the implication of urban forms, with the reference to the effect of varying density, height and greenery density. The results show that GnPR, which related to the present of greenery, have the most significant impact on the energy consumption by reducing the temperature by up to 2 °C. The results also strongly indicate an energy saving of 4.5% if the urban elements are addressed effectively.     

Empirical validation of models to compute solar irradiance on inclined surfaces for building energy simulation

Accurately computing solar irradiance on external facades is a prerequisite for reliably predicting thermal behavior and cooling loads of buildings. Validation of radiation models and algorithms implemented in building energy simulation codes is an essential endeavor for evaluating solar gain models. Seven solar radiation models implemented in four building energy simulation codes were investigated: (1) isotropic sky, (2) Klucher, (3) Hay–Davies, (4) Reindl, (5) Muneer, (6) 1987 Perez, and (7) 1990 Perez models. The building energy simulation codes included: EnergyPlus, DOE-2.1E, TRNSYS-TUD, and ESP-r. Solar radiation data from two 25 days periods in October and March/April, which included diverse atmospheric conditions and solar altitudes, measured on the EMPA campus in a suburban area in Duebendorf, Switzerland, were used for validation purposes. Two of the three measured components of solar irradiances – global horizontal, diffuse horizontal and direct-normal – were used as inputs for calculating global irradiance on a south-west façade. Numerous statistical parameters were employed to analyze hourly measured and predicted global vertical irradiances. Mean absolute differences for both periods were found to be: (1) 13.7% and 14.9% for the isotropic sky model, (2) 9.1% for the Hay–Davies model, (3) 9.4% for the Reindl model, (4) 7.6% for the Muneer model, (5) 13.2% for the Klucher model, (6) 9.0%, 7.7%, 6.6%, and 7.1% for the 1990 Perez models, and (7) 7.9% for the 1987 Perez model. Detailed sensitivity analyses using Monte Carlo and fitted effects for N-way factorial analyses were applied to assess how uncertainties in input parameters propagated through one of the building energy simulation codes and impacted the output parameter. The implications of deviations in computed solar irradiances on predicted thermal behavior and cooling load of buildings are discussed.     

A review of building energy regulation and policy for energy conservation in developing countries

The rapid growth of energy use, worldwide, hfs raised concerns over problems of energy supply and exhaustion of energy resources. Most of the developed countries are implementing building energy regulations such as energy standards, codes etc., to reduce building energy consumption. The position of developing countries with respect to energy regulations implementation and enforcement is either poorly documented or not documented at all. In addition, there is a lack of consistent data, which makes it difficult to understand the underlying changes that affect energy regulation implementation in developing countries. In that respect, this paper investigates the progress of building energy regulations in developing countries and its implication for energy conservation and efficiency. The present status of building energy regulations in 60 developing countries around the world was analysed through a survey of building energy regulations using online survey. The study revealed the present progress made on building energy regulations in relation to implementation, development and compliance; at the same time the study recommends possible solutions to the barriers facing building energy regulation implementation in the developing world.     

Computer validation of scale model tests for building energy simulation

Dimensional analysis was used to derive the physical properties for a small-scale model building and its heating, ventilating, and air conditioning (HVAC) system. The model was built, and its thermal response was studied over a number of heating and cooling cycles. Temperature variation was recorded in the form of temperature/time plots. Experimental results showed the model to be capable of realistic behaviour. Detailed comparisons with full-scale response could not be made, since an imaginary prototype was assumed. Recent computer simulation, however, produced results analogous to those obtained from the model tests. This suggests that small-scale models can be used to quantitatively reproduce building energy response. Current efforts are being directed towards the modelling of an existing building, in which both air temperature and velocity will be measured. The aim is to validate small-scale modelling as a viable tool in building-energy research.     

Application and development of solar energy in building industry and its prospects in China

China is the second largest country in energy consumption. More and more energy demand pressures cause the Chinese government to review its economy and energy policies in order to support the sustainable development. In China, the building sector amounts to 27.8% total energy consumption, which is only behind the industry sector. China has abundant solar energy resource, which is extensively applied to buildings. Therefore, solar energy utilization in buildings has become one of the most important issues to help China optimize the energy proportion, increasing energy efficiency and protecting the environment. Solar energy resource and its district distribution in China are introduced in detail in this paper, and the representative solar energy application to the building sector is highlighted as well. The solar energy utilization obstacles, especially policy disadvantages in building sector in China, are reviewed. Moreover, the application prospects of solar energy in building sector are presented in combination with the China economic and household industry growth.     

Future proof construction—Future building and systems design for energy and fuel flexibility

Buildings of the future must be designed and constructed to reduce energy demand. From a thermal point of view, technologies to minimise heating needs already exist. But in order to reduce future cooling requirements, more positive action will be required. This applies both in commercial buildings, where cooling demand is already significant, and in the domestic sector, where air conditioning is gaining a foothold. A further problem in the housing sector is the rising electrical demand from appliances, which has increased significantly in recent years. In addition to changes in construction practice, such as using means to mitigate the effects of warming climates, better, more sophisticated control systems must be more fully utilised, such as the automatic switching off of appliances, and advanced controls and metering.     

An economic analysis of energy requirements and input costs for tomato production in Turkey

The aim of this study was to examine direct and indirect input energy in per hectare in tomato (industrial type) production and compare it with production costs. The research also sought to analyse the effect of farm size. For this purpose, the data were collected from 95 tomato farmers by questionnaire method. The results indicated that tomato production consumed a total of 45.53 GJ ha⁻¹ of which diesel energy consumption was 34.82% followed by fertilizer and machinery energy. Output–input energy ratio and energy productivity were found to be 0.80 and 0.99 kg of tomato MJ⁻¹, respectively. Cost analysis revealed that the most important cost items were labour costs, machinery costs, land rent and pesticide costs. According to the benefit–cost ratio, large farms were more successful in energy use and economic performance. It was concluded that energy use management at farm level could be improved to give more efficient and economic use of energy.     

Long-term validated simulation of a building integrated photovoltaic system

Electrical and thermal simulations of a building integrated photovoltaic system were undertaken with a transient system simulation program using real field input weather data. Predicted results were compared with actual measured data. A site dependent global-diffuse correlation is proposed. The best-tilted surface radiation model for estimating insolation on the inclined surface was selected by statistical tests. To predict the module temperature, a linear correlation equation is developed which relates the temperature difference between module and ambient to insolation. Different combinations of tilted surface radiation model, global-diffuse correlation model and predicted module temperature were used to carry out the simulation and corresponding simulated results compared with the measured data to determine the best combination which gave the least error. Results show that modification of global-diffuse correlation and module temperature prediction improved the overall accuracy of the simulation model. The monthly error between measured and predicted PV output was lied below 16%. Over the period of simulation, the monthly average error between measured and predicted PV output was estimated to be 6.79% whereas, the monthly average error between measured and predicted inverter output was 4.74%.     

Evaluation of energy requirements for all-electric range of plug-in hybrid electric two-wheeler

Recently plug-in hybrid electric vehicles (PHEVs) are emerging as one of the promising alternative to improve the sustainability of transportation energy and air quality especially in urban areas. The all-electric range in PHEV design plays a significant role in sizing of battery pack and cost. This paper presents the evaluation of battery energy and power requirements for a plug-in hybrid electric two-wheeler for different all-electric ranges. An analytical vehicle model and MATLAB simulation analysis has been discussed. The MATLAB simulation results estimate the impact of driving cycle and all-electric range on energy capacity, additional mass and initial cost of lead-acid, nickel-metal hydride and lithium-ion batteries. This paper also focuses on influence of cycle life on annual cost of battery pack and recommended suitable battery pack for implementing in plug-in hybrid electric two-wheelers.     

Method for simulating predictive control of building systems operation in the early stages of building design

A method for simulating predictive control of building systems operation in the early stages of building design is presented. The method uses building simulation based on weather forecasts to predict whether there is a future heating or cooling requirement. This information enables the thermal control systems of the building to respond proactively to keep the operational temperature within the thermal comfort range with the minimum use of energy. The method is implemented in an existing building simulation tool designed to inform decisions in the early stages of building design through parametric analysis. This enables building designers to predict the performance of the method and include it as a part of the solution space. The method furthermore facilitates the task of configuring appropriate building systems control schemes in the tool, and it eliminates time consuming manual reconfiguration when making parametric analysis. A test case featuring an office located in Copenhagen, Denmark, indicates that the method has a potential to save energy and improve thermal comfort compared to more conventional systems control. Further investigations of this potential and the general performance of the method are, however, needed before implementing it in a real building design.     

Comprehensive energy and economic analyses on a zero energy house versus a conventional house

A zero energy house (ZEH) was built side by side with a baseline house in suburban Las Vegas. Actual energy performance measurements were carried out on the incorporated energy saving features and solar applications. The data show that a radiant barrier and a water-cooled air conditioner are major contributors to the energy savings, while an insulated floor slab and thermal mass walls are not effective for energy-conservation during cooling periods. Photovoltaic roof tiles produce enough green power to cover the use in the ZEH, and the solar water heater can reach a peak efficiency of 80%. The energy saving contribution of each incorporated component was obtained using Energy10 and eQUEST3.6 models, and then these codes were used for economic application evaluation. The two analysis codes yield similar results that compare well with the actual building performance data. Four items are clearly economically valuable for these applications: high performance windows, compact fluorescent lights, highly-insulated roofs and air conditioners with water-cooled condensers. PV tiles show a good financial return when rebates are considered. The Integrated Collector Storage (ICS) unit has a high efficiency but with a little higher thermal price. Thermal mass walls are too costly to have wide market appeal.     

Owners perception on the adoption of building envelope energy efficiency measures in Swedish detached houses

The paper focuses on Swedish homeowners’ need for and perceptions about adopting building envelop energy efficiency measures. The paper is based on a questionnaire survey of 3059 homeowners (response rate of 36%) selected by stratified random sampling during the summer of 2008. The results showed that 70–90% of the respondents had no intention of adopting such a measure over the next 10 years. The main reasons for non-adoption were that homeowners were satisfied with the physical condition, thermal performance, and aesthetics of their existing building envelope components. A greater proportion of respondents perceived that improved attic insulation has more advantages than energy efficient windows and improved wall insulation, but windows were more likely to be installed than improved attic insulation. Respondents gave high priority to economic factors in deciding on an energy efficiency measure. Interpersonal sources, construction companies, installers, and energy advisers were important sources of information for homeowners as they planned to adopt building envelope energy efficiency measures. Policy measures to facilitate the rate of adoption of energy efficient building envelope measures are discussed.     

Calculation procedure of the shading factor under complex boundary conditions

Together with the evolution of buildings and systems, energy assessment models have become more and more detailed, requiring a precise evaluation of the building loads and gains.For an accurate analysis of solar heat gains, technical standards introduce an external shading reduction coefficient of the incident solar radiation, called shading factor. Its value is provided for simple geometries, which are usually not suitable to properly describe a real environment. In addition, the relations adopted to evaluate the shading factor are based on simplified hypotheses, which cause non-negligible errors when compared to more complex algorithms.The objective of this study is the development of a calculation procedure of the shading factor under complex boundary conditions. The algorithms have been implemented in a software tool written in Matlab language. It can provide for the value of the shading factor on a generically oriented and tilted surface. After setting the site and the time for the simulation, generic-shaped windows can be modelled. The external environment, which can be imported from DXF files, can include a horizon profile, generic-shaped obstructions and vegetation. The calculation can be performed for every sky condition: clear, average or generic. In addition, the simulation can be run to obtain instantaneous, daily average or monthly average shading factor values.     

Calculation of solar irradiance profiles from hourly data to simulate energy systems behaviour

In various studies of solar energy systems (sizing, estimation of production), we need solar irradiation data collected with a smaller time interval than those often available in databases (often hourly irradiations). We compare three models (constant, linear and extraterrestrial) which simulate an hourly profile of solar irradiance and allow the determination, with a given reliability, of minute data of global solar irradiation from hourly measured irradiations. These models are compared from the point of view of various statistical tests using data collected on a Mediterranean site. The extraterrestrial model shows very satisfying results and improves greatly the accuracy compared with a constant model.     

Energy and economic analysis of an integrated solar absorption cooling and heating system in different building types and climates

The use of solar energy in buildings is an important contribution for the reduction of fossil fuel consumption and harmful emissions to the environment. Solar thermal cooling systems are still in their infancy regarding practical applications, although the technology is sufficiently developed for a number of years. In many cases, their application has been conditioned by the lack of integration between cooling and heating systems. This study aims to evaluate the potential of integrated solar absorption cooling and heating systems for building applications. The TRNSYS software tool was used as a basis for assessment. Different building types were considered: residential, office and hotel. The TRNSYS models are able to run for a whole year (365 days), according to control rules (self-deciding whether to operate in heating or cooling modes), and with the possibility of combining cooling, heating and DHW applications. Three different locations and climates were considered: Berlin (Germany), Lisbon (Portugal), and Rome (Italy). Both energy and economic results are presented for all cases. The different local costs for energy (gas, electricity and water) were taken into account. Savings in CO₂ emissions were also assessed. An optimization of solar collector size and other system parameters was also analysed.