Building integration photovoltaic module with reference to Ghana: using triple junction amorphous silicon

This paper assesses the potential for using building integrated photovoltaic (BIPV) roof shingles made from triple-junction amorphous silicon (3a-Si) for electrification and as a roofing material in tropical countries, such as Accra, Ghana. A model roof was constructed using triple-junction amorphous (3a-Si) PV on one section and conventional roofing tiles on the other. The performance of the PV module and tiles were measured, over a range of ambient temperatures and solar irradiance. PVSyst (a computer design software) was used to determine the most appropriate angle of tilt. It was observed that 3a-Si performs well in conditions such as Accra, because it is insensitive to high temperatures. Building integration gives security benefits, and reduces construction costs and embodied energy, compared to freestanding PV systems. Again, it serves as a means of protection from salt spray from the oceans and works well even when shaded. However, compared to conventional roofing materials, 3a-Si would increase the indoor temperature by 1-2 °C depending on the surface area of the roof covered with the PV modules. The results presented in this research enhance the understanding of varying factors involved in the selection of an appropriate method of PV installation to offset the short falls of the conventional roofing material in Ghana

Energy generation and consumption in Ghana

Electricity consumption in Ghana is estimated to be increasing by 10% per annum due to the demand from the growing population. However, current sources of production (hydro and thermal facilities) generate only 66% of the current demand. Considering current trends, it is difficult to substantiate these basic facts, because of the lack of information. As a result, research into the existing sources of generating electricity, electricity consumption and prospective projects has been performed. This was achieved using three key techniques; review of literature, empirical studies and modelling. The results presented suggest that, current annual installed capacity of energy generation (i.e. 1960 MW) must be increased to 9,405.59 MW, assuming 85% plant availability. This is then capable to coop with the growing demand and it would give access to the entire population as well as support commercial and industrial activities for the growth of the economy. The prospect of performing this research is with the expectation to present an academic research agenda for further exploration into the subject area, without which the growth of the country would be stagnant

Domestic cold pitched roofs in the UK: - effect of using different roof insulation materials

The type and thickness of insulation on the topside horizontal of cold pitched roofs has a significant role in controlling air movement, energy conservation and moisture transfer reduction through the ceiling to the loft (roof void) space. To investigate its importance, a numerical model using a HAM software package on a Matlab platform with a Simulink simulation tool has been developed using insitu measurements of airflows from the dwelling space through the ceiling to the loft of three houses of different configurations and loft space. Considering typical UK roof underlay (i.e. bituminous felt and a vapour permeable underlay), insitu measurements of the 3 houses were tested using a calibrated passive sampling technique. Using the measured airflows, the effect of air movement on three types of roof insulation (i.e. fibreglass, cellulose and foam) was modelled to investigate associated energy losses and moisture transport. The thickness of the insulation materials were varied but the ceiling airtightness and eaves gap size were kept constant. These instances were considered in order to visualize the effects of the changing parameters. In addition, two different roof underlays of varying resistances were considered and compared to access the influence of the underlay, if any, on energy conservation. The comparison of these insulation materials in relation to the other parameters showed that the type of insulation material and thickness, contributes significantly to energy conservation and moisture transfer reduction through the roof and hence of the building as a whole

Principles and calibration of solid phase microextraction fibre (passive sampler) for measurements of airflow and air infiltration in dwellings

Tracer gas techniques have been the most appropriate experimental method of determining airflows and ventilation rates in houses. However, current trends to reduce greenhouse gas effects have prompted the need for alternative techniques, such as passive sampling. In this research passive sampling techniques have been used to demonstrate the potential to fulfil these requirements by using solutions of volatile organic compounds (VOCs) and solid phase microextraction (SPME) fibres. These passive sampling techniques have been calibrated against tracer gas decay techniques and measurements from a standard orifice plate. Two constant sources of volatile organic compounds were diffused into two sections of a humidity chamber and sampled using SPME fibres. From a total of four SPME fibres (two in each section), reproducible results were obtained. Emission rates and air movement from one section to the other were predicted using developed algorithms. Comparison of the SPME fibre technique with that of the tracer gas technique and measurements from an orifice plate showed similar results with good precision and accuracy. With these fibres, infiltration rates can be measured over grab samples in a time weighted averaged period lasting from 10 minutes up to several days. Key words: passive samplers, solid phase microextraction fibre, tracer gas techniques, airflow, air infiltration, houses

Post occupancy evaluation of a sports pavilion within an educational establishment

The focus of buildings performance is no longer merely the basic functions of providing shelter or safeguarding human lives and property. Concerns relating to indoor environment quality (IEQ) has increasingly been a topic of interest, mainly in terms of occupants’ comfort and energy consumption. However, these concerns are not often assessed in educational buildings especially sports venues for reasons unknown. This study presents an evaluation of a sports pavilion at University of Reading. IEQ variables, energy consumption and occupancy patterns have been investigated through in-situ measurements which are analysed in comparison with existing benchmark and building energy simulation. The in-situ measurements reflect that the IEQ in the pavilion is considered to be generally satisfactory after comparison with benchmarks. The findings also show that the building has good air-tightness hence high-energy retention. The building was modelled using Integrated Environmental Solutions (IES), a building simulation software. The model verified against metered energy consumption showed a 1.6% deviation. The paper also discussed relevant recommendations to maintain good IEQ and energy efficiency

Investigating the level of awareness of building assessment tools in the construction industry of Botswana

Environmental building assessment tools have been developed to measure how well or poorly a building is performing, or likely to perform, against a declared set of criteria, or environmental considerations, in order to achieve sustainability principles. Knowledge of environmental building assessment tools is therefore important for successful design and construction of environmentally friendly buildings for countries. The purpose of the research is to investigate the knowledge and level of awareness of environmental building assessment tools among industry practitioners in Botswana. One hundred and seven paper-based questionnaires were delivered to industry practitioners, including architects, engineers, quantity surveyors, real estate developers and academics. Users were asked what they know about building assessment, whether they have used any building assessment tool in the past, and what they perceive as possible barriers to the implementation of environmental building assessment tools in Botswana. Sixty five were returned and statistical analysis, using IBM SPSS V19 software, was used for analysis. Almost 85 per cent of respondents indicate that they are extremely or moderately aware of environmental design. Furthermore, the results indicate that 32 per cent of respondents have gone through formal training, which suggests ‘reasonable knowledge’. This however does not correspond with the use of the tools on the ground as 69 per cent of practitioners report never to have used any environmental building assessment tool in any project. The study highlights the need to develop an assessment tool for Botswana to enhance knowledge and further improve the level of awareness of environmental issues relating to building design and construction

Morphometric analysis of body and claw dimensions of building dwelling UK bat species: to aid knowledge of bat interactions with roosting surfaces

The increasing use of non-woven materials, such as breathable roofing membranes (BRMs) within buildings that either currently contain a bat roost or may do in the future, has led to concerns over bat safety by those involved in bat conservation in the UK. Whilst some information is currently available on the selection of roosts in roofs by bats, along with technical specifications of individual membranes, there is no research that has investigated the interactions between the two. Prior to determining the methods needed to test interactions between bats and BRMs, a series of preliminary investigations were conducted; including research and physical measurements on selected anatomical features of bats commonly found roosting in buildings in the UK. Data on body size and shape were gathered from a combination of experimental measurements of bat specimens (deceased) and information collated from literature. Data on bat claw morphology were collected by applying a method used to measure raptor talons, measurements obtained included; width, length and the curvature (hook ratio) of their claws. The results of this research provide additional information about bat body and claw morphometrics. It was found that bat species/group had a significant effect upon the length, width and curvature of the claws (to varying degrees). Pipistrelle species have the shortest and third narrowest claws, whereas serotines have the longest and widest claws on average. The curvature of the claws does not vary greatly between species; however, more variation was seen in the lower portion of the claws. The results from this research also demonstrate that the current standard industry tests do not represent the fine scale at which a bats claws interact with their roosting surfaces. Consequently, this information can be used to aid the development of industry tests for determining the suitability of BRMs for use in bat roosts

Energy overview of Botswana: generation and consumption

Botswana has a basic need to explore its energy concept, this being its energy sources, generation and percentage of the population with access to electricity. At present, Botswana generates electricity from coal, which supplies about 29% (on average) of the country’s demand. The other 71% is imported mainly from South Africa (Eskom). Consequently, the dependence of Botswana on imports posses threats to the security of its energy supply. As a result, there is the need to understand the bases for a possible generation expansion that would substantiate existing documentation. In view of this need, this study investigates the existing energy sources as well as energy consumption and production levels in Botswana. The study would be further developed by making projections of the energy demand up until the year 2020. The key techniques that were used include; literature review, questionnaire survey and an empirical study. The results presented indicated that, current dependable operation capacity (i.e. 100MW) should be increased to 2,595 MW or more assuming 85% plant efficiency. This would then be able to meet the growing demand for energy use. In addition, the installed capacity would be able to support commercial and mining activities for the growth of the economy

Double jeopardy: the potential for problems when bats interact with breathable roofing membranes in the United Kingdom

In order to reduce environmental impacts and achieve sustainability, it is important to balance the interactions between the built and natural environment. The construction industry is becoming more aware of ecological concerns and the importance that biodiversity and maintenance ecosystem services has for sustainability. Bats constitute an important component of urban biodiversity and several species in the UK are highly dependent on buildings, making them particularly vulnerable to anthropogenic and environmental changes. Many buildings suitable for use as bat roosts often require re-roofing as they age and traditional bituminous roofing felts are frequently being replaced with breathable roofing membranes (BRMs). In the UK new building regulations and modern materials may substantially reduce the viability of existing roosts, yet at thesame time building regulations require that materials be fit for purpose. Reports suggest that both bats and BRMs may experience problems when the two interact. Such information makes it important to understand how house dwelling bats and BRMs may be affected. This paper considers the possible ways in which bats and BRMs may interact, how this could affect existing bat roosts within buildings and the implications for BRM service life predictions and warranties. Keywords –Breathable Roofing Membranes, Bats in Buildings, Material Deterioration, Sustainability, Conservation, Biodiversi

Barriers of solar energy uptake and the potential for mitigation solutions in Barbados

Understanding the barriers that inhibit the deployment of renewable energy technologies to achieve long-term reductions in carbon emissions from the use of fossil fuels is paramount to Barbados. Although there are targets towards renewable energy (solar, wind, biomass, geothermal) uptake, the share of these technologies in the energy mix does not exist in Barbados due to the total dependence on fossil fuels. In this paper, a review of potential challenges and the main problems for deployment of alternative energy sources is presented. Through interviews, questionnaires with a focus group of key personnel’s, the paper documents the lack of renewable energy sources (with emphasis on solar energy) as one of the main alternatives to meet the carbon emission targets set by the country. The barriers and challenges facing the implementation of solar energy deployment have been clarified. From the results, it is evident that significant policy barriers still exist at the country level, which has reduced the effectiveness of a concerted national effort to deploy renewables. The current policy landscape which benefits from fossil fuel imports, the lack of technical know-how and the lack of research and development in the renewable energy space are amongst the key barriers identified. The paper also outlines the key policy’s frameworks, regulatory environment and the lack of incentives, which encompasses the renewable energy sector, and presents a critical analysis of the barriers faced by the industry. A mitigation framework is proposed to bridge the gap of solar energy (renewable energy) deployment