Investigation of Solar Thermal Energy in Buildings: A Report

This report investigates solar thermal technology for buildings as a low/zero carbon energy solution. It provides an executive summary, introduction to the technology, and an overview of the current state of solar thermal building applications, including the use of building-integrated solar thermal (BIST) systems. The report explores the impact of solar thermal technology on the energy system, detailing its replacement of traditional fuels and contribution to global energy production. It also examines technical developments, such as industrial solar Fresnel collector fields, and future innovations like Hetero-Epitaxial solar cells. The report addresses barriers to adoption, such as high initial costs and a lack of stakeholder interest, while also highlighting opportunities for growth and development. The report concludes with a summary of the key findings and implications of solar thermal technology in the context of sustainable energy practices.

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SUSTAINABLE ENERGY
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Investigation of a Low/Zero Carbon Energy Technology
Executive Summary
This paper investigates the use of solar thermal for buildings as a technology for low or zero
carbon energy. Solar thermal technology involves the installation of solar heating and cooling
systems into new or existing buildings for the purposes of heating water, heating or cooling of
building spaces. Statistics show that a number of countries have adopted the technology and
over472 GWh of thermal power generated with 135 million tons of CO2 emissions successfully
mitigated. The solar technology is responsible for about 22%of the global total energy and is
estimated to replace some of the non-renewable sources of energy like coal by 2050.However,
there are a number of barriers hindering the development and installation of solar heating and
cooling systems in buildings including the high initial costs and lack of both interest and
technical knowledge. Also, there a number of current technical developments in this technology
including future ones like the use of Hetero-Epitaxial solar cell and Liquid filter with Plasmonic
Nanoparticles.
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Table of Contents
Executive Summary.........................................................................................................................1
Introduction......................................................................................................................................3
Current State of the Solar Thermal Building Technology...............................................................3
Impacts of Building Solar Thermal Technology on the Energy System and Other Fuels..............6
Technical Developments of Building Solar Thermal Technology..................................................7
Barriers and Opportunities in the Building Solar Thermal Technology..........................................9
Conclusions....................................................................................................................................10
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Introduction
High carbon emissions have been identified as the main cause of global climatic changes such as
the global warming. The high emissions have been spear headed by the current world
developments and industrialization, therefore to ensure sustainable developments, the level of
CO2 emissions must be reduced to the minimal limits.
The term low/zero carbon technology refers to the various technologies that result into low level
emissions of carbon (iv) oxide (CO2) into the environment. There are a number of such
technologies that have been incorporated in various sectors or industries ranging from the
transport to the building industry. The various low carbon technologies include offshore wind,
tidal power, wave power, carbon capture and storage, low carbon district heating, alternatives to
petrol/diesel road vehicles, solar thermal for buildings, concentrated solar power, rechargeable
battery storage and nuclear fission or fusion. This paper investigates solar thermal for buildings
as a low/zero carbon technology (Zhao 2015).
Current State of the Solar Thermal Building Technology
Solar energy has been identified as one of the most efficient and readily available renewable
sources energy in the world. The solar energy has largely been put into uses primarily for heating
and cooling buildings, supply of hot water in the residential buildings and the supply of power in
the buildings. Through the building integrated solar thermal (BIST) systems, this technology has
proven to be very efficient in energy savings, building operational costs and reduction in the
carbon emissions (Zhang 2015).The working of a BIST system is based on a group of system
modular collectors which first receives the radiations before converting it into heat energy. The
circular working medium then receives part of the converted heat which is then transported to the
first heat storage unit. In the storage unit, there is an exchange of heat between the refrigerating
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pump and the medium for circulation. Through this interactions, the circulating medium reduces
in temperature thus absorbing the heat in the facades or screens ready for the next circle of heat
exchange.
Figure 1: A Typical Building Integrated Solar Thermal Systems (Zhang 2015).
There are various categories BIST systems that are employed in buildings .The categorization is
based on the medium of the heat transfer which includes air based, hydraulic and the PCM based
types. The air based system works in such a way that the intake air is heated by the solar heat and
supplied to the building for ventilations and heating. In the hydraulic systems the effectively
collected solar heat is used in the heating of water using other advanced solar devices for supply
of hot water and building heating. The PCM based type of BIST systems combines both water
and air or any other hydraulic means for the storage of solar heat energy. These systems are able
to solar heat during generation and release the energy for usage during poor solar periods. It is
important to note that the air based systems are relatively cheaper in terms of cost but less
efficient due rapid loss of heat in the air masses (Zhang 2015).
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In the current state, the application of solar thermal systems has been witnessed in the generation
of hot water in the residential buildings and small scale plants. The use of solar energy in
buildings has been in the rise in various countries with some setting up policies and incentives to
encourage solar usage (International Renewable Energy Agency 2015).
According to the International Energy Agency (2019), through the solar heating and cooling
programme, a total of 472 GWh was put into operation at the end of 2017 period. So, the use of
building solar thermal systems rose by 4% during the 2015/2016.Studies also show that countries
like China, US, Turkey, India and Brazil are among the leading in the utilization of solar thermal
systems. In addition, a total of 135 million tons of carbon IV oxide has been saved in the year
2017 when 388 tWh of solar energy saved over 42 tons of oil (IEA-SHC 2018).
China is still leading in the utilization of the thermal solar systems in the residential buildings.
However, there has been a slight decline in the installation residential solar systems in China and
Europe with the global thermal capacities declining by about 4.2% at the end of 2017.The
decline is attributed to the rising competition from other renewable technologies. However,
markets like India, Mexico and turkey have recorded growth in the residential solar thermal
energy installation (IEA-SHC 2018). Figure 5 shows the current state of use of worldwide use
solar heating and cooling systems.
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Figure 2: Solar Heating and Cooling Markets in 2016 (IEA- Solar Heat Worldwide 2018)
Impacts of Building Solar Thermal Technology on the Energy System and Other Fuels
The building solar thermal systems have been identified as the simplest way of harnessing the
solar energy for the purpose heating water and building spaces. The system is cost effective and
can easily replace the use of other sources like electricity in the domestic water heating activities.
Currently, use of solar hot water accounts for over 472 GWh of the world thermal power. This
means a significant quantity of other sources of fuels previous used has been replaced by the
solar thermal power. For instance the use of unglazed solar collectors in the heating of swimming
pools has been witnessed in countries like USA and Australia. Also, according to Jenny (2014),
the use of electricity in heating water and building spaces have been overtaken by the use of
solar heating systems in the UK with the systems providing about 70% of the domestic hot water
used annually in the country.
According to projections by the IEA (2019), solar energy will replace the coal energy by the
year 2050 with capacity of generating 22% of the total global energy. It has been estimated that
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renewable sources of energy currently contributes about 30% of the global energy. The CO2
contributions by the renewable sources like solar energy is significantly lower than the fossil
sources like coal.
Solar industrial reports also indicate that thermal solar is less expensive than the photovoltaic
(PV) solar systems. Also, the thermal solar systems are very effective in the provision and
conservation of energy than the PV, the solar thermal system is able to store the energy unlike
the PV which directly converts the solar energy to electricity thus effective only day hours. The
cost of the building solar thermal technology has been in the decline therefore beating the cost of
electricity generated from fossil fuels like diesel and petrol.
Generally, the solar thermal technology for buildings has reduced the cost of energy in the
operation of buildings, both residential and public. Also, it is slowly replacing other sources of
energy like coal and other fossil fuels like oil (Solar Heat Worldwide 2018).
Technical Developments of Building Solar Thermal Technology
The planet is increasingly industrializing and advancing in technologies thus the solar thermal
technology has reported massive developments over the years since its introduction to the
market. Technical developments of this technology mainly focuses on making the system more
efficient and consequently saving on its installation and operational costs.
Some of the current developments in the solar thermal technology for buildings is the expansion
of collectors through the establishment of the industrial Solar Fresnel Collector Fields. This
establishment covers very large areas of up to 2100 m2 with temperatures of up to 200oC and is
used in the cooling of large areas like stadiums (Dipl.-Ing 2017). Two methods have currently in
use for the collection of solar thermal including the line focus collection and the point focus
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collection. The line focus collection method is the old method and involves the use of a parabola
shaped mirror which is made to rotate along an axis while tracking the movement of the sun
throughout the day. The solar energy is fully utilised in the process of rotation. On the other
hand, the point focus collection method entails setting up of a series of mirrors around a central
tower. The mirrors collectively focuses the rays from the sun to a single point on the tower for
utilization. However, it is important to note that the line focus method is less costly and involves
less technical requirements than the point focus method of collection (Solar Thermal 2017).
Figure 5: Football Stadium Solar Cooling System
Developments have also been observed in the circulation and storage of the hot water including
the establishment of large water storage tanks, cylindrical, cubical and pressurized polymeric
stores. Also, recent development includes the modular hot water store which withstands quite
higher pressures of up to 2.5 bars and requires very little spaces in the building including lower
losses of heat (Dipl.-Ing 2017).
Some of the future technical developments in the solar thermal for buildings include the ongoing
developments of Hetero-Epitaxial solar cell and Liquid filter with Plasmonic Nanoparticles.
Hetero-Epitaxial solar cell is a low cost hybrid converter that once developed will be able to
perform two functions including electricity thermal heat generation through splitting of sunlight.
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The Liquid filter with Plasmonic Nanoparticles is a hybrid solar systems that will be able to
capture and convert the non-visible wavelengths of light to heat energy (Renewable Energy Hub
2018).The overall result of such future developments is to improve efficiency and lower costs of
solar thermal technologies in buildings.
Barriers and Opportunities in the Building Solar Thermal Technology
The main barrier facing the development and implementation solar thermal technologies in
buildings is the high initial cost of installation of the system. The current cost of installing solar
thermal system ranges between 8,000 and 10,000 US dollars which is quite expensive for most
residential building owners. Policies have been established by various governments to control the
costs of solar systems in line with the need for reducing the levels of CO2 emissions.
The lack of interest from various stakeholders involved in the building environment is another
barrier that is greatly facing the solar thermal technology. Architects and civil engineers involved
in the design of buildings always consider solar modules as technical devices rather than the
components of a building. For this reason, solar systems are not always incorporated in most
designs given that the clients also have no information on the available solar systems. Agencies
like the International Energy Agency are in the processes of conducting surveys and providing
awareness about the long term benefits of solar systems (Farkas 2015).
In addition, there architects and engineers have insufficient technical knowledge on the
installation of solar systems in buildings. The available building design codes does not provide
sufficient information of such installations thus other people specifically specialised in the solar
system need to be employed during constructions.
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Opportunities are available for adoption of solar thermal technology ranging from government
incentives, subsidised costs and favourable government policies. Governments such as the
Australia Government provide rebates and a considerable financial incentives to various solar
owners. Also, other benefits like tax credits are provided by various governments depending the
size and type of solar systems installed by citizens. According to Crago & Chernyakhovskiy
(2017), such opportunities by various governments have effectively increased the demand for the
installation solar heating and cooling systems in building across the world. This has finally led to
a significant mitigation of CO2 emissions.
Conclusions
Personally, it is worth noting that the use solar thermal for buildings as a technology for low or
zero carbon energy is a very effective and cheaper than other technologies available. Statistical
data have shown that there is rising demand in the use of technology and a significant amount of
CO2 emissions mitigated from the environment. Also, projections by the IEA show that the use
solar thermal technologies will be able to replace the use fossil fuels like coal and reduce the
generation of electricity from non-renewable sources like oil. Therefore this technology should
be adopted in both public and residential buildings across the world.
In conclusion, various governments should put emphasis on the adoption of the solar heating and
cooling systems in buildings. The barriers facing the development of this technology such high
costs and lack of interest and knowledge among various stakeholders should be mitigated. Also,
the need for sustainable development is very important for a country and the world at large due
to the recent concerns over the rising climatic changes. The use solar heating and cooling
systems in building is one of the factors for sustainable developments that should be taken
seriously. Finally, there is evidence that the use solar thermal for buildings has more advantages
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than the few advantages. Despite the high installation costs, there are other long term benefits
like the lower building operational costs and significant mitigation of carbon emissions.
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