Yzel, I - The Design of a Low-Tech Solar Heating System for Residential use in Climatic Zone 2 of... by jacques_23

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THE DESIGN OF A LOW-TECH SOLAR HEATING SYSTEM FOR RESIDENTIAL USE IN CLIMATE ZONE 2 OF SOUTH AFRICA

IAN YZEL 209041170

- Research Document by Ian Yzel 209041170 Submitted in partial fulfillment of the requirements for the degree Master of Architecture in Architectural Technology (Structured) at the Department of Architecture and Industrial Design

in the FACULTY OF ENGINEERING AND THE BUILT ENVIRONMENT at the TSHWANE UNIVERSITY OF TECHNOLOGY Supervisor: Prof J Laubscher Co-Supervisors: Mr SP Steyn Mr M van Schoor PRETORIA 2021

Front page - Figure 1: Front page: Nongoma informal settlement: KZN (Author, 2021)

DEPARTMENT of ARCHITECTURE and INDUSTRIAL DESIGN

DECLARATION ON PLAGIARISM The Department of Architecture and Industrial Design emphasises integrity and ethical behaviour concerning the preparation of all assignments. Although the lecturer/ study leader/ supervisor/ mentor will provide you with information regarding reference techniques and ways to avoid plagiarism, you also have a responsibility to fulfil. Should you feel unsure about the requirements, you must consult the lecturer/ study leader/ supervisor/ mentor concerned before submitting an assignment. You are guilty of plagiarism when you extract information from a book, article, web page, or other sources of information without acknowledging the source and pretending that it is your own work. This applies to cases where you quote verbatim and when you present someone else’s work in a somewhat amended (paraphrased) format or when you use someone else’s arguments or ideas without acknowledgment. You are also guilty of plagiarism if you copy and paste information directly from an electronic source (e.g., a website, e-mail message, electronic journal article, or CD ROM), even if you acknowledge the source. You are not allowed to submit another student’s previous work as your own. Furthermore, you are not allowed to let anyone copy or use your work to present it as their own. Any student who produces work alleged to be plagiarised will be referred to the Academic Affairs Disciplinary Committee for a ruling. Plagiarism is considered a severe violation of the University’s regulations and may lead to your suspension from the University. In accordance with Regulation 4.1.11.1(j) of Chapter 4 (Examination Rules and Regulations), and Regulations 15.1.16 and 15.1.17 of Chapter 15 (Student Discipline) of Part 1 of the 2021 Prospectus, I (full names & surname):

Ian Yzel

Student number:

209041170

Declare the following: 1. I understand what plagiarism entails, and I am aware of the University’s policy in this regard. 2. I declare that this assignment is my own original work. Where someone else’s work was used, it was acknowledged, and reference was made according to departmental requirements. 3. I did not copy and paste any information directly from an electronic source (e.g., a web page, electronic journal article, or CD ROM) into this document. 4. I did not make use of another student’s previous work and submitted it as my own. 5. I did not allow and will not allow anyone to copy my work to present it as his/her own work. I further declare that this research proposal is substantially my own work. Where reference is made to the work of others, the extent to which that work has been used is indicated and fully acknowledged in the text and list of references.

05 January 2022 Signature

Date

Table of Contents ABSTRACT ................................................................................................................v 1. CHAPTER 1: PROJECT CONTEXT ......................................................................1 2. CHAPTER 2: LITERATURE REVIEW....................................................................5 2.1 Pretoria as study region................................................................................6 2.2 Test results from existing installation ............................................................7 2.3 Internal air circulation ...................................................................................8 2.4 Airborne transmission of infections ...............................................................9 2.5 Heat storage from solar air heater ................................................................9 2.6 Heat storage material and calculations.........................................................9 2.7 Optimum solar angle ..................................................................................11 3. CHAPTER 3: RESEARCH OUTLINE ..................................................................13 3.1 Research Objective ....................................................................................14 3.2 Research Question ....................................................................................14 3.3 Delimitations ...............................................................................................16 3.4 Methodology ...............................................................................................16 3.5 Research Context .......................................................................................17 3.6 Research Paradigm ....................................................................................17 3.7 Research Design ........................................................................................19 4. CHAPTER 4: SYSTEM DESIGN ..........................................................................22 4.1 Concept ......................................................................................................23 -

Detail model of solar air heater Exploded model of rock bed heat collector Exploded model of solar air heater

4.2 Construction of Solar Air Heater .................................................................30 4.2.1 Solar air heater 4.2.2 Rock bed heat collector

5. CHAPTER 5: PILOT STUDY ................................................................................40 5.1 Pilot Study Part 1 ........................................................................................41 5.1.1 Testing equipment 5.1.2 Methodology 5.1.3 Results 5.1.4 Conclusion

5.2 Pilot Study Part 2 ........................................................................................45 5.2.1 Methodology 5.2.2 Results 5.2.3 Calculations 5.2.4 Conclusions 5.2.5 Alterations and changes

6. CHAPTER 6: DATA PROCUREMENT ................................................................51 Part 3: Introduction ...........................................................................................52 6.1 Full experiment Part 1: Ventilated heating system .....................................52 6.1.1 Introduction 6.1.2 Methodology 6.1.3 Results 6.1.4 Conclusion

6.2 Full experiment Part 2: Enclosed heating system .......................................61 6.2.1 Introduction 6.2.2 Methodology 6.2.3 Results 6.2.4 Conclusion

6.3 Full experiment Part 3: Ventilated cooling system ......................................69 6.3.1 Introduction 6.3.2 Methodology 6.3.3 Results 6.3.4 Conclusion

6.4 Full experiment Part 4: Enclosed cooling system .......................................73 6.4.1 Introduction 6.4.2 Methodology 6.4.3 Results 6.4.4 Conclusion

6.5 Comparison ASHRAE thermal comfort and results from experiment .........79 6.5.1 Ventilated heating system (Winter range 20°C to 23°C) 6.5.2 Enclosed heating system (Winter range 20°C to 23°C) 6.5.3 Ventilated cooling (Summer range 23°C to 26.6°C) 6.5.4 Enclosed cooling (Summer range 23°C to 26.6°C) 6.5.5 ASHRAE standard 6.5.6 Conclusion from comparison

6.6 Application of solar heating/ cooling system ...............................................80 7.2.1 New built solar heating system application 7.2.2 Retrofit solar heating system application

6.7 Cost analysis ..............................................................................................83

7. CHAPTER 7: CONCLUSION ...............................................................................84 7.4 Recommendation .......................................................................................85 7.4.1 Heating system recommendation 7.4.2 Cooling system recommendation

7.5 Opportunities for communities ....................................................................86 7.5.1 Local labour opportunities 7.5.2 Local economy upliftment

iii

Water and air, the two essential fluids on which all life depends, have become global garbage cans. ― Jacques-Yves Cousteau

ABSTRACT According to the latest statistics issued on electricity tariffs in South Africa, the tariffs have increased five times more than inflation between 2007 and 2020. Low-income households often use non-renewable fuels such as coal and paraffin to generate indoor heat to substitute for electricity. Generating heat from non-renewable fuels is the leading cause of indoor air pollution and poor health conditions for the occupants of these households. The study aims to improve the indoor comfort levels for low-income households by substituting non-renewable fuels. To substitute the use of non-renewable fuels, a costeffective and energy-efficient system should be designed and tested. To improve the indoor temperature while allowing for ventilation, a solar heating system with heat storage capacity was developed by evaluating existing studies on solar air heaters and heat storage materials and systems. The heating system was constructed and tested to determine its effectiveness. Through developing a cost-effective solution, the study investigated the possibility of constructing the solar heating system from waste and off-cut materials. If solar heating can be implemented successfully, the aim is to substitute nonrenewable fuels. The system will assist with internal ventilation and limit the spread of viruses or infections within enclosed spaces. The proposed heating system will transfer the external, ambient air through the system and allow heated fresh air to enter the housing units without opening windows or doors during the winter season. The study was carried out with the following components: a solar air heater with dimensions of 1000mm (L) x 500mm (W) x 100mm (H) and a rock-bed heat collector. A study was conducted to observe the performance of the rock bed heat collector when using different types of rocks to store heat and various positions, layouts, and arrangements for the system to make recommendations regarding optimal performance. The data acquired from the pilot study was implemented to conduct the final study to determine the effectiveness of the solar heating system. The study used the minimum ASHRAE human comfort levels to assess the efficacy and cost-effectiveness of the design proposal.

Through testing the proposed heating system, it was anticipated that the indoor temperature and airflow would improve through iterative design. Suppose the use of non-renewable fuels can be replaced by implementing the solar heating system; in that case, the thermal comfort levels of informal dwellings can be improved without reliance on harmful sources of energy. Keywords: Air pollution, non-renewable fuels, conventional heating, fresh air, rock bed heat collector, alternative heating system, renewable energy, cost-effective.

‘

PROJECT CONTEXT • History of informal settlements • Existing population of informal settlements in South Africa • Contributing factors to poor indoor thermal comfort • Focus of the study

1. PROJECT CONTEXT Informal dwellings can be defined as unplanned housing units on land which has not been surveyed or proclaimed (HDA 2017: 8). Furthermore, an informal dwelling can be defined as a makeshift structure without the approval of the Local Municipality. The data published by the Housing Development Agency (HDA) of South Africa (2017) indicates that the number of households living in informal settlements in South Africa stands at a total of 1,249,777 households, containing 3,306,697 individuals with an average of 2,6 people per household of 2 to 3 individuals (HDA 2017: 18). In a study by the Department of Environmental Affairs (DEA) of South Africa on dense, lowincome households with an income below R3 500 per month, a need is identified to address the impact of air pollution generated from the burning of non-renewable fossil fuels for indoor temperature regulation. (Government Gazette no. 40088, 2016: 11, 23). Information obtained on the ambient air quality from more than 90 monitoring stations identified geographical areas within Gauteng, Free State, Mpumalanga, Limpopo, Northwest, and Western Cape Province, which have polluted ambient air above 50µg/m3 and proved to be unhealthy for human inhabitation (Government Gazette no. 40088, 2016: 8). Due to the lack of thermal insulation in the walls, floor, and roof, the internal temperature of an informal dwelling can differ between as little as 4-5˚C from the ambient temperatures during the winter season (Naicker et al, 2017: 1).

Low-income households burn paraffin or coal (alternatively referred to as non-renewable fuels) within living spaces to generate heat. A research study published by the South African Department of Environmental Affairs (DEA, 2008) has indicated that six metropolitan areas in South Africa are responsible for 69% of the ambient air pollution in the selected geographical areas (Friedl et al, 2008: 2). The study also estimated that 9 000 deaths are caused annually in South Africa due to indoor air pollution from non-renewable fuels. Therefore, it is essential to investigate, identify and develop an alternative indoor heating method. One such method is solar energy that is both renewable and non-toxic when implemented. Informal dwellings was the focus of the case study.

According to a study published by the World Health Organization (WHO), it was found that the rate of spread of viruses and infections in enclosed and poorly ventilated rooms is much

higher compared to ventilated spaces (WHO, 2020). It is anticipated that the proposed heating system can improve ventilation by replacing the internal air with warmed fresh air. The fresh air enters from the bottom of the solar air heater and replaces the internal air. The proposed study will address indoor air pollution and improve the indoor temperature. The study will focus on providing a cost-effective and energy-efficient solution for indoor space heating. The integrated indoor heating system should be designed to be retrofitted to any informal dwelling at an affordable price. The study will also focus on creating job opportunities by making use of local labour within low-income communities. The construction of a solar heating system will require the skills of an electrician, plumber, and carpenter. Figure 2 illustrates the proposed concept design of the solar air heating system, which will be developed and tested further in Chapters 5 and 6.

Figure 2: Typical illustration of proposed heating system experimental set-up during the winter season (Author, 2021).

Figure 3 below illustrates the proposed concept design of the solar air heating system, which can be utilised for cooling during the summer season. The concept will be developed, tested, and discussed further in Chapters 5 and 6. During the evening, the cool ambient airflow through the system cools the rocks. The hot internal airflow over the rocks during the daytime. When implementing the system to a house, the warm air from the internal space will be extracted to flow through the rock bed, transfer heat to the rocks and cool down the air, which will be supplied back to the internal space.

Figure 3: Typical illustration of proposed cooling system experimental set-up during the winter season (Author, 2021).

LITERATURE REVIEW • • • • • • • •

Chapter 2: Introduction Study region Results from previous studies Air circulation Airborne transmission of infections Heat storage from solar air heater Heat storage material and calculations Optimum solar angle

: 5

2. INTRODUCTION Chapter 2 discusses various topics supporting the study, which will be used throughout the document. This chapter will focus on previous studies, existing problems, and information to form a base for the study. 2.1 Pretoria as the study region A survey (Census, 2019) was carried out on 11 783 798 households to determine the total number of “shacks not in a backyard” (referred to as informal dwellings in this study) in South Africa. The results from the survey indicated that nationally, 1 375 858 households make use of an informal dwelling. The survey indicated that 448 383 households in Gauteng use informal dwellings — this was the highest of all provinces (HDA, 2019:44). Furthermore, the survey results indicated that in Gauteng, Tshwane, and Johannesburg have the highest informal dwellings at 216 066 households (HDA, 2019:46). The annual mean temperature in Pretoria is 18.25 C° (using the annual maximum and minimum temperatures). During May to August (winter season), the average temperature is 13.5 C° (Climate-data.org, 2020). According to the Koppen-Geiger climate classification, Pretoria is classified as ‘humid subtropical’ with cold interior temperatures (Kottek et al., 2006). Pretoria has almost no rainfall during the winter season, with 28 days of sunshine each month from May-August. Therefore, the experiment will be conducted in Pretoria, situated in climatic zone two (temperate interior) of the South African climatic zones map (SANS 204:2011: 30). A further study can be done by testing the system on informal dwellings in the remaining regions and climate zones.

Figure 4: Map of South Africa and Gauteng (Vectorstock, 2021)

2.2 Test results from existing installations Classrooms in New Zealand are grossly under-ventilated in cold weather and have excessively high bacteria levels, potentially leading to adverse respiratory infections and other health effects (Bassett et al., 1999, McIntosh 2011). Nearly all New Zealand classrooms depend entirely on natural ventilation via open windows (Cutler-Welsh, 2006). The school days are in line with the availability of solar radiation. Therefore, it is found that schools are the ideal environment for utilising solar air heaters for indoor heating and ventilation (Boulic et al., 2014: 1). The problem identified within the classrooms of New Zealand is similar to that identified within the informal dwellings based in South Africa. The system was implemented to address under-ventilated spaces, high levels of bacteria, and indoor temperatures. The results proved that solar air heaters, with the dimension of 75 mm x 3 000 mm x 1 020 mm (3m²) constructed from a 6 mm thick transparent cover, 2 mm thick black felt absorbent layer, perforated aluminium backplate, and 18-watt photovoltaic panel, providing electricity to the circulation fan, can generate sufficient heat for a classroom of 200 m² (Boulic et al., 2014: 2).

The results showed that the intervention positively impacted the school environment with decreased carbon dioxide levels and 2,5 times less energy consumption (Boulic et al., 2014: 3). The study on classrooms shows that human comfort levels can be improved by using a solar air heater system by improving indoor temperatures and air quality. The solar air heater still requires a circulation fan assisting with the indoor air ventilation and a method to store heat. 2.3 Internal air circulation In Switzerland, an investigation was done using a vertical, wall-mounted solar air heater (13.1m x 2.2m) with an electrical fan to circulate fresh air into an industrial building to improve the indoor air quality and temperature (Sicre and Baumann 2015: 140). The industrial building does not have any thermal insulation other than the sheet metal skin of the building with a floor area of 300 m² and 8.2 m high; the total volume of the structure is 2 460 m³. The scale of this project is larger than the proposed housing units used in this study; however, the solar air heater should be able to perform equal or better on a smallscale project like the industrial building (Sicre and Baumann 2015: 139). The data gathered from the study indicated that the solar air heater replaced the indoor air sufficiently at a flow rate of 50m³/h per 1m² from provided by a 28m² solar-air heater. The air within the building was replaced by fresh air within 1 hour 35 minutes, which indicates that, on a larger scale, using a solar air heater for ventilation proved efficient. The solar air heater produced an average of 30°C of heating into the indoor space over three months (Sicre and Baumann 2015: 142). The similarity between the industrial building and the informal-dwelling units is that both are constructed primarily from sheet metal and a mild steel frame with no additional thermal insulation in the walls or roof to improve the thermal comfort levels. Although there are similarities between the industrial building and the housing units, the system should still be tested in a controlled environment in South Africa to obtain results that can be used in a further study to implement the system on informal dwellings.

2.4 Airborne transmission of infections According to a study by the KTH Royal Institute of Technology, it was found that tuberculosis is one of the top ten causes of death and is spread through the air. Ten million people fell ill with tuberculosis, and 1.5 million people died in 2018. Furthermore, it was found that an infected person spreads these viruses into the air by coughing, sneezing, or spitting. Only a few germs are required to be inhaled to infect another person (Lutzow & Mikiver, 2020:6). According to a World Health Organization (WHO) study, the spread of these viruses can be reduced when internal spaces are ventilated by replacing the internal air approximately three times per hour (WHO, 2020). It is anticipated that the spread of these viruses can be reduced when implementing a solar heating system with fresh air circulation.

2.5 Heat storage from the solar air heater When a solar air heater is used in conjunction with a rock bed, the rock bed can store heat for optimal efficiency and supply heat during the evening (Marongiu, Soprani, Engelbrecht, 2019: 1). Developing a cost-effective solar air heater that can be constructed from waste material will enable communities to construct their own solar heating systems. According to a study by Politeknik Dergisi (2020), it is found that a solar air heater can be constructed from waste materials and still be effective (Sözen et al., 2020: 9). Further in the study, it was indicated that a solar air heater, constructed from waste materials, increased the thermal internal comfort levels between 33% and 42% (Sözen et al., 2020: 6). 2.6 Heat storage material and calculations A study was conducted to investigate the possibility of storing heat within a rock, water, and phase change materials (Eckhoff and Okos 2013: 2). After comparing the three alternatives, it was found that rock would be the best material for heat storage on a solar air heater system, which uses air to transfer heat (Eckhoff and Okos 2013: 5). Once the system is installed, maintenance is minimal, and few elements can decrease the performance of the storage (Eckhoff and Okos 2013: 2). Furthermore, rock is readily available and affordable and relatively easy to compose, compared to water and phase change material which can also be used as heat storage materials. From previous test results, rocks between 100 mm

to 150 mm with round edges have shown the best results to store heat with airflow velocity at 10 m per second. The rocks must be free of dust and small stones, which will restrict airflow (Eckhoff and Okos 2013: 6). Table 1: Heat storage characteristics of rock (Eckhoff and Okos 2013: 4) HEAT STORAGE CHARACTERISTICS OF ROCK Storage material

Bulk density

Specific heat

Imperial information Rock

100lb/ft³

0.2BTU/lb.°F

Metric translated information Rock

1601.8kg/m³

0.658J/kg.°C

The information in Table 1 will be used in Table 2 to determine the amount of rock required to discharge sufficient heat into a room or space. Table 2 will indicate the formula used in Chapter 4 to calculate the amount of rock required for the experiment. The information available from the study conducted is all in imperial format. It will be translated to the metric format as indicated in Tables 1 and 2. Table 2 is utilised to determine the amount of rock required for a specific room/ space as heat storage material.

Table 2: Calculation for heat storage material required (Eckhoff and Okos 2013: 6) VOLUME OF ROCK REQUIRED AS STORAGE MATERIAL Description

Example

Example (Metric)

(Imperial) a

Heating requirement of space/ room

15000BTU

4396 Watt/ hour

Duration for the heat required

24 hours

Storage reserve

3 days

Total heat required (a x b x c)

1 080 000BTU

316 512 Watt/ hour

Bulk storage material (table 1)

100lb/ft³

1601.8kg/m³

Specific heat storage material (table 1)

0.2BTU/lb°F

0.658J/kg.°C

Temperature range

50°F

10°C

Heat from storage material (e x f x g)

1000BTU/ft³

10 550.4 Watt/m³

Storage material required (d / h)

1080ft³

30m³

2.7 Optimum solar angle According to a study conducted by the Department of Mechanical and Aeronautical Engineering at the University of Pretoria, the optimum tilt and azimuth angles were determined through a system called Solys 2 tracking system. Furthermore, the system was used to track the solar exposure for 365 days in Bloemfontein, Durban, Graaff-Reinet, Pretoria, Richtersveld, Stellenbosch, Van Rhynsdorp and Vryheid (Le Roux, 2019: 6). The azimuth is the angle between the horizontal axes and vertical perpendicular axes.

The study proved that a solar panel at the optimum tilt and azimuth angle could generate 10% more solar energy when placed in a fixed position. A solar panel tracking the sun’s movement can generate, on average, 45% more solar energy (Le Roux, 2019: 17). The results from the study are tabled below: Table 3: Optimum solar angles (Le Roux, 2019: 15). Study Results Location Optimum Tilt

Optimum Azimuth

Bloemfontein

28⁰

6⁰

Durban

29⁰

8⁰

Graaff-Reinet

29⁰

-7⁰

Pretoria

26⁰

4⁰

Richtersveld

26⁰

-14⁰

Stellenbosch

27⁰

-4⁰

Van Rhynsdorp

27⁰

-12⁰

Vryheid

29⁰

1⁰

RESEARCH OUTLINE • • • • • • • •

Chapter 3: Introduction Research objective Research questions Delimitations Methodology Research Context Research Paradigm Research Design

INTRODUCTION

Chapter 3 sets an outline of the research document, which will be used throughout. This chapter discusses the following aspects: • • • • • • •

Research objective Research questions Delimitations Method Research Context Research Paradigm Research Design

This chapter ends with the design summary, which combines the process of unfolding the research document.

3.1 RESEARCH OBJECTIVE The study aims to determine the potential use of a solar air heating system with heat storage material (rock) by testing the system’s performance as an alternative method for indoor heating and ventilation in informal dwellings based in South Africa. Consequently, the objectives of the study are: 3.1.1 To acquire the initial ambient temperatures. 3.1.2 To acquire specific temperature and solar radiation data to identify indoor comfort levels defined by ASHRAE comfort models. 3.1.3 To conduct a detailed experiment by constructing the solar heating system with all its parts. 3.1.4 To analyse the data and determine findings and infer recommendations. 3.2 RESEARCH QUESTIONS: A solar air heating system is proposed to address the current living conditions and thermal comfort levels in informal dwellings by testing the potential use of a cost-effective and energy-efficient heating system. The occupants of the identified dwellings generally cannot afford to purchase electricity for space heating. The households instead make use of affordable non-renewable fuel resources; however, they compromise their health in the process. A rock-bed heat collector will be combined with a solar air heater system to produce sufficient heat during the day and night. The study will focus on informal dwellings based in

South Africa. The current problem identified for informal dwellings is uniform across all lowincome communities. The main problem is divided into sub-problems with the related hypothesis in Table 1 below. Table 4: Integrating the main aim, sub problem and hypotheses SUB-PROBLEM (1 - 5)

HYPOTHESIS (1 – 5)

(Posed as a question) Sub-Problem 1:

Hypothesis 1:

What alternative method of heating is It is hypothesised that a solar air heating system available without using hazardous fuels can be used as an alternative heating method to generate sufficient indoor heat? by using solar energy in South Africa. Sub-Problem 2:

Hypothesis 2:

How can a solar-air-heater system improve indoor air quality?

It is hypothesised that when a solar-air-heater system with a solar-powered fan and rock bed heat collector is implemented, the system will circulate and replace internal, stale air with cleaner external air.

Sub-Problem 3:

Hypothesis 3:

How will the solar air heater store sufficient heat to be used during the evening if the system relies only on solar energy?

It is hypothesised that a solar air heater system combined with a rock bed heat collector to store heat during the day could discharge heat that can be used during the evening.

Sub-Problem 4:

Hypothesis 4:

Can the system produce sufficient heat It is hypothesised that the proposed system can and ventilation? produce sufficient heat and ventilation. Sub problem 5:

Hypothesis 5:

Will the resulting system be costeffective for low-income communities?

It is hypothesized that constructing a solar air heater with a rock bed is an affordable heating method with low maintenance costs for lowincome communities.

3.3 DELIMITATIONS The following delimitations are applicable to the study: 3.3.1 The proposed study will investigate the performance of the rock bed heat collector by providing heat during the evening. 3.3.2 Weather data from Pretoria will be obtained to compare the effectiveness of the system. 3.3.3 The study will aim to improve internal airflow but will not pay attention to the health impact of occupants due to the polluted air and deaths caused by polluted air. 3.3.4 The study will address the internal temperature. 3.3.5 The focus of the study will not be on the thermal performance of the external envelope. 3.3.6 The focus of the study will be to provide a heating system that is not reliant on electricity or non-renewable fuels to create a healthier environment for low-income households. 3.3.7 The study will not involve heat-storage materials other than rock. 3.4 METHODOLOGY The proposed study will be done through iterative design development research. The results from the experiment will be used to determine if the system will improve the internal temperature and facilitate ventilation during both day and night. The ambient temperature readings during the experiment will be used to determine the effectiveness of the system. 3.4.1 Phase 1: Pilot Study (Chapter 3) The study will consist of the following three phases: •

Phase 1 – Pilot study,

•

Phase 2 – Data procurement, and

•

Phase 3 – Design iteration.

During the pilot study, a basis for the study will be formed by gathering information on each component used during the test. Data from previous studies will be used to determine the optimum size of the solar air heater and the rock bed heat collector. The solar air heater will be tested to determine the total heat generated during the day. The rock bed heat collector will be connected to the solar air heater to test the heat storage capacity of the rock bed.

3.4.2 Phase 2: Data procurement (Chapter 4 & 5) During Phase 2 of the study, the three components tested in the pilot study will be connected. The test during Phase 2 will determine the performance of the solar air heater during the day and night. The results from the pilot study are used to indicate the heat loss factor between the components. The experiment will be done in isolation to determine the optimum performance without any tampering on the system. The results will indicate whether the thermal comfort increases when the solar air heater system with the rock bed heat collector is implemented. 3.4.3 Phase 3: Design iteration (Chapter 6) During Phase 3, the experiment will be conducted through iterative design development research by testing the solar heating system over multiple days during both the summer and winter seasons. The potential for space heating will be tested over multiple days to explore the possibility of seasonal charging. The solar heating system will be tested during the summer season to determine the potential to cool internal spaces. The solar air heater will be covered and inactive during the summer to limit solar energy and heat. The methodology will be discussed further in chapter 6, parts 3 and 4. After completing phases 1, 2, and 3, a feasibility study will be done to determine the exact cost of the system to be constructed from waste or off-cut materials available in low-income communities. 3.5 RESEARCH CONTEXT The research context was formed through research done on previous studies published about the existing real world problem and previous experiments done on a solar air heater in combination with a rock bed to address the problem of indoor air pollution. 3.6 RESEARCH PARADIGM Table 5 communicates the researcher’s normative position regarding the positivist and interpretivist research paradigms, using a scale of predispositions formulated by Laubscher (2011:15):

Table 5: The researcher’s paradigm indicated on the model developed by Laubscher (2011:15) RESEARCHER’S PARADIGM

Meta-theoretical assumptions

Ontology

Detached experience Person (researcher) and reality are separate.

Epistemology

Objectivity Objective reality exists beyond the human mind.

Research object

Separate The research object has inherent qualities that exist independently from the researcher.

Research method

Content analysis through statistics Preferred research methods include laboratory experiments, field experiments, surveys, etc.

Theory of truth

Statement = Truth→ Objective Reality Establishing a direct relationship between the research statements and reality.

Validity

Certainty: The data truly measures reality. A direct relationship exists between measurements + phenomena.

Reliability

Replicability Research results can be reproduced by the researcher or other researchers to achieve a consistent result.

Strongly Agree

Agree

Neutral

Alternative terms: Quantitative, scientific, experimental, hard, reductionist, prescriptive, psychometric, etc.

Disagree

Pre-disposition of the researcher on a continuum scale Strongly Disagree

Positivism

Interpretivism

Alternative terms: Qualitative, soft, non-traditional, holistic, descriptive, phenomenological, anthropological, naturalistic, illuminative, etc. Integrated experience Person (researcher) and reality are inseparable (life-world). Subjectivity Knowledge of the world is intentionally constituted through a person’s lived experience Incorporated The research object is interpreted in the light of the meaning structure of the person’s (researcher’s) lived experience. Content analysis through interpretation Preferred research methods include case studies, ethnographic studies, phenomena-graphic studies, ethnomethodological studies, etc. Initial interpretation = Truth → confirms a meaning (from researcher’s experience) Truth as intentional fulfilment: interpretations of research object match lived experience of the subject. The knowledge (claim) is defensible Evaluation criteria include credibility, transferability, dependability, and ability to confirm. Interpretive awareness Researchers recognise and address the implications of their subjectivity.

Normative position of the researcher:

The researcher can separate himself from the research process. The researcher can only be isolated from the process for not less than a week. An objective thought process will be followed, focusing on facts and observations from the research.

The research object exists independently from the researcher and won’t be affected by the researcher’s experience. However, since the experimental setup is a design project, the researcher’s frame of reference will influence the trajectory of the study, and new data may reframe the original research questions. The primary method for obtaining data will be through the use of data loggers. The use of surveys will also be implemented to obtain information on the knowledge of this research topic.

The researcher has no previous experience or involvement with this study; therefore, the outcome will not be influenced by past familiarity.

There is a direct connection between the data composed and the results thereof. The researcher will be observant and truthful throughout the research process. It is possible that the study can be repeated by different researchers, but the outcome may vary because of environmental circumstances.

3.7 RESEARCH DESIGN The relationship between the research question, data required, and data analysis constitute the basis of the research design. Fellows and Liu argue that the definition of different research styles varies to such an extent that the boundaries between different styles are not well defined (2003:21). However, in Research Methods for Construction, Fellows and Liu (2003:21-28) discuss different research styles and strategies according to the respective authors in Table 6 below. Table 6: Summary of research styles Research styles/strategies Research styles as termed by Bell (1993) (as cited in Fellows & Liu, 2003: 21-28)

Research strategies as termed by Yin (1994) (as cited in Fellows &

Implementation in the proposed (1997) (as cited in Fellows & Liu, 2003: 21-28) study Shortened description as defined by Fellows and Liu

Liu, 2003: 21-28)

Action

Research intentionally attempts to affect change in the social system.

Not applicable

Ethnographic

A scientific study of races and cultures involving the hermeneutic circle.

Not applicable

Histories

The past is studied based on the research questions

Yes

‘How?’ and ‘Why?’ Archival analysis

Present or past is studied; little control over independent variables is required.

Yes

Surveys

Statistical sampling represents a population and often employs questionnaires and interviews.

Not applicable

Case studies

An in-depth investigation of certain aspects through interviews with key’ factors.’

Partially

This is usually conducted in laboratories to determine the relationship between variables.

Yes

Experiments Experimental

(Including quasiexperiments)

Using the format and outline developed by Laubscher (2011: 19), the different phases of the research design are communicated in Table 7.

Table 7: Summary of the research design RESEARCH DESIGN: IMPLEMENTATION OF SOLAR AIR HEATER WITH HEAT STORAGE MATERIAL AS AN ALTERNATIVE HEATING SYSTEM ON RDP AND INFORMAL DWELLINGS IN CLIMATIC ZONE 4 OF SOUTH AFRICA. PHASE 1: A REVIEW OF APPLICABLE LITERATURE PHASE 1.1 (Refer to Chapter 2)

Theme: Thermal comfort (Indoor ventilation and temperature) Focus area: Informal dwellings in dense low-income communities Data source: Selected literature 1.1 Understanding the current problem identified for space heating in informal dwellings. 1.2 Determine the minimum requirements and standards for indoor air quality 1.3 Shortly describe the current methods of indoor heating 1.4 Briefly describe the impact of the current methods used for heating in informal and RDP dwellings PHASE 1.2 (Refer to Chapter 2)

Theme: Climatic classification Focus area: Identifying the available alternative methods for indoor heating Data source: Relevant Literature 1.2.1 Investigate the available alternative methods of heating that can benefit the study and the community 1.2.2 Determine the viability of the proposed heating system proposed in the study through previous studies conducted 1.2.3 Investigate and analyse previous applications and results of the proposed heating system in regions with similar environmental characteristics. ▼

PHASE 2: PILOT STUDY PHASE 2.1: (Refer to Chapter 5) Theme:

Experiment

Focus Area:

Determine the appropriate size of the solar air heater and rock bed heat collector applicable to the volume of the units used in the study.

Data source:

Research material and computer analysis

2.1.1

Determine the size/ ratio of the solar air heater when taking into consideration the floor area of the housing units and also the type of material to be used for the solar air heater for optimal performance.

2.1.2

Determine the size of the rock bed heat collector to be constructed for sufficient heat storage. ▼

PHASE 2.2 (Refer to Chapter 5) Theme:

Testing of measuring instruments

Focus Area:

Determine the accuracy of the data obtained from the simulation when comparing the results with the results of previous studies and experiments

Data source:

Research material + experiment results

2.2.1

Determine the effectiveness of the experiment compared to the results of previous studies conducted and weather data of Pretoria to determine the viability of the study. ▼

PROGRESS REVIEW (See note1) NOTE1: When conducting a progress review, the researcher should decide whether a further investigation into the thermal performance of insulation materials will be beneficial to the study. ▼

PHASE 3: DATA PROCUREMENT (cf. Chapter 6) Theme:

Collection data

Focus area:

Data collection from the experiment when implementing the system

Data source:

Experiment

3.1

Determine the correct size and ratio of the solar air heater and rock bed on an informal dwelling. Use the annual weather data to determine the effectiveness of the system.

3.2

▼

PHASE 4: DATA INTERPRETATION (cf. Chapter7) 4.1

Analysis of data collected and compared

4.2

Statistical description and analysis of the data

4.3

Interpretation of the data ▼

PHASE 5: FINDING & CONCLUSION (Chapter 7) Recommendation and conclusion deduced from the produced and analysed data during chapters 4 and 5. ▼

PHASE 6: PROPOSAL Proposal to implement the solar air heater system in informal dwellings for better thermal comfort and the lowering of air pollution.

SYSTEM DESIGN • Chapter 4: Introduction • Concept designs - Detail model of solar heating system - Exploded model rock bed heat collector - Exploded model of solar air heater • Construction of Solar Heating System - Solar air heater - Rock bed heat collector

4 INTRODUCTION Chapter 4 presents the concept development of the solar heating system. The concepts are presented through annotated hand sketches. The chapter also presents the concept sketches developed into 3D rendered models. The chapter discusses the materials used for constructing the full-scale model to be tested in chapters 5 and 6. The chapter ends with calculating the amount required for the rock bed heat collector to determine the size of the box to be constructed. 4.1 CONCEPT The basic principles of the proposed solar heating system are based on a solar air heater providing heat during the day and a rock bed heat collector storing heat during the day to produce heat during the evening. Figure 5 illustrates the concept of the solar heating system. The ambient air enters the solar air heater from the bottom, and exchanges heat between the air and the heat collector plate. The heated air is transferred through the solar air heater into the rock bed heat collector. It is anticipated that the heat from air flowing from the solar air heater is transferred to the surface and core of the rocks. The heat is stored within the rocks during the evening by circulating air through the rock bed into a room or space.

Figure 5: Concept diagram drawing of solar air heater and rock bed heat collector (Author, 2021).

Figure 6 illustrates the concept sketches of the solar air heater to be used for the experiment. The solar air heater will be constructed from waste and off-cut materials as per section 4.2.

Figure 6: Concept diagram drawing of a solar air heater (Author, 2021)

Figure 7 illustrates the obstacles placed within the solar air heater to increase the heat transfer rate between the air and backing plate. Obstacles increase the time the airflow through the solar air heater and therefore increase the heat transfer rate.

Figure 7: Concept drawing of obstruction in solar air heater (Author, 2021).

Figure 8 illustrates that the rock bed heat collector consists of an inner and outer envelope. The outer envelope consists of a 19mm thick timber shutter board with a 50mm thick polystyrene insulation between the inner and outer envelope. The inner envelope consists of a 19mm thick timber shutter board filled with 100mm 150mm rock to capture the heat from the solar air heater. The box will have an inlet for hot air from the solar air heater and an outlet for heat from the rock to be circulated into a room or space.

Figure 8: Concept drawing of rock bed (Author, 2021)

Figure 9 illustrates the complete solar heating through a concept model, which will be used during the experiment to determine the efficiency. The concept model consists of the solar air heater fixed on the enclosed rock bed heat collector box. As indicated in the literature review section, the optimum tilt angle for Pretoria is 26°; this will be the angle of the solar air heater during the experiment.

Figure 9: Concept model of complete solar air heating system to be tested during the experiment (Author, 2021)

Figures 10 and 11 below illustrate the concept models illustrate the exploded view of the rock bed heat collector and the solar air heater with all the components.

Figure 10: Concept model: Exploded view of rock bed heat collector box (Author, 2021)

In Figure 11, the exploded concept model of the solar air heater is illustrated.

Figure 11: Concept model: Exploded view of a solar air heater (Author, 2021).

4.2 CONSTRUCTION OF SOLAR HEATING SYSTEM Most of the materials to construct the solar heating system was procured from local resources or waste and off-cut materials from previous construction projects. The electrical components such as the electric fan and solar panel were bought from an electronics shop. In this section, the materials used during the construction process are documented. The materials are grouped for the construction of the solar air heater and the rock bed heat collector. Each item will indicate the original use, origin (if applicable), type of material and the material’s use for the project. 4.2.1 Solar air heater: 4.2.1.1

Heat collector plate and obstruction material

The original use of material: 0,8mm thick Chromadek roof sheeting. Origin: Obtained from scrap metal yard in Silverton, Pretoria. Use of material: The material is used for the heat collector plate of the solar air heater. Cost: R10 per/kg with a total cost of R70.00. The material was cut to size to fit the internal dimensions of the solar air heater.

Figure 12: Chromadek roof sheet (Author, 2021)

Figure 13: Obstacles in solar air heater (Author, 2021)

4.2.1.2 Timber frame The original use of material: 152mm x 38mm SA Pine roof trusses. Origin: Obtained from a construction project; the material was removed and redundant. Use of material: Main external frame of the solar air heater. Cost: No cost, redundant material from a construction project.

Figure 14: SA Pine timber frame for solar air heater (Author, 2021)

Figure 15: SA Pine timber planks

4.2.1.3 Glass panel The original use of material: Off-cut glass from large panes cut to size for window frames. Origin: Off-cut glass obtained from BJ Glass and Aluminium in Silverton, Pretoria. Use of material: Translucent panel over solar air heater box. Cost: R30.00

Figure 16: Glass panel (Author, 2021)

4.2.1.4 Insulation The original use of material: Bubble wrap packaging material and used newspapers. Origin: Obtained from a waste bin in Silver Lakes, Pretoria. Use of material: Insulation material between the heat collector plate and backing board. Cost: No cost.

Figure 17: Newspaper insulation (Author, 2021)

Figure 18: Bubble wrap insulation (Author, 2021)

In Figures 17 and 18, the newspaper was placed on the heat collector plate with the bubble wrap placed on top of the newspaper to act as insulation material to prevent heat loss from the solar air heater.

4.2.1.5 Backing board The original use of material: Timber courier box for fragile items. Origin: Put out as waste by neighbouring house Use of material: 20mm Thick backing board for solar air heater box. Cost: No cost. The timber courier box was dismantled and cleaned. Only the timber without any water damage was used for the construction of the solar air heater.

Figure 19: Timber courier box (Author, 2021)

4.2.1.6 Solar panel and circulation fan Origin: The solar panel and circulation fan was bought from Electronics FG Description: The circulation fan is 12 V, 1,5 Watt with a 12 V, 5 Watt solar panel fixed to the front of the solar air heater. Cost: Total cost R168.00 The total cost of the solar air heater will be discussed further in Chapter 7.

Figure 20: Circulation fan (Author, 2021) Figure 21: Solar panel (Author, 2021)

4.2.1.7 Complete solar air heater box: In Figure 22, the complete solar air heater box, which will be used during the pilot study in Chapter 4. The internal surface of the solar air heater was painted black to increase the heat generated. The box consists of the main frame, translucent glass panel, heat collector plate, circulation fan, solar panel, backing board, insulation, and black paint for the internal surface.

Figure 22: Complete solar air heater (Author, 2021)

4.3 CONSTRUCTION OF ROCK BED HEAT COLLECTOR To enable the system to store heat generated from the solar air heater, a rock bed heat collector will be utilised with the solar air heater to store the heat. The rock bed heat collector will be constructed from waste or off-cut materials. The rock bed heat collector needs to be insulated to reduce the heat-loss factor when the rocks within the box are charged during the day. The rock bed heat collector has a size of 500mm x 500mm x 1000mm and can store 0.25³ of rock. The rocks within the box will be 100mm to 150mmØ in size, as indicated in the literature review in Chapter 3. All of the materials used to construct the rock bed heat collector are off-cut and waste materials available from previous construction projects and dumpsites. Below are the materials used for the construction of the rock bed heat collector.

4.3.1 Rock bed heat collector 4.3.2.1 Envelope construction The original use of material: 19mm Thick timber shutter board. Origin: Off-cut timber obtained from a previous construction project Use of material: External envelope constructed from the timber shutter board. Cost: No cost The timber shutter board was cut to size to construct a 1000mm x 500mm x 500mm box filled with rock. The internal surface is to be covered with insulation material to prevent heat loss.

Figure 23: Off-cut shutter board (Author, 2021) (Author, 2021)

Figure 24: Construction of heat collector box

4.3.2.2 Insulation material The original use of material: 50mm Thick polystyrene packaging material Origin: Waste bin in Silver Lakes, Pretoria. Use of material: The polystyrene material was used to insulate the envelope of the rock bed heat collector. Cost: No cost The insulation material used to construct the rock bed heat collector was obtained from a waste bin where packaging material is disposed of. The polystyrene was in different sizes and shapes and was cut to fit the internal surface of the box.

Figure 25: Insulation in waste bin (Author, 2021)

Figure 26: Bulk insulation obtained (Author, 2021)

Figure 27: Insulation fixed to timber box (Author, 2021)

4.3.2.3 Heat storage material The original use of material: Excavated slate rock from a construction site. Origin: Obtained from a construction site in Olympus, Pretoria. Use of material: The rock is used as heat storage material in the rock bed heat collector box. Cost: No cost The nominal size of the rocks should be between 100mm and 150mm dia. for optimum performance, as indicated in the literature review in Chapter 3.

Figure 28: Rocks from a construction site (Author, 2021)

Figure 29: Size of rocks obtained (Author, 2021)

4.3.2.4 Circulation pipes The original use of material: Redundant 50mmØ plumbing pipes. Origin: Off-cut pipes obtained from a construction site in Olympus, Pretoria. Use of material: The pipes transfer the air from the solar air heater through the rock and out into the living space or room. The U-PVC bents required for the project were bought from Plumblink to connect the pipes. Cost: R64.00 The inlet pipes are connected to the top of the solar air heater and the top and the outlet at the bottom of the rock heat collector box. The hot air must flow over the rock before the air reaches the outlet pipe. The outlet of the rock bed heat collector will supply hot air to a space or room when implemented on a house.

Figure 30: Placement of U-PVC pipes

Figure 31: Inlet pipe to rock bed heat collector

Figure 32: Outlet from rock bed heat collector

4.3.2.5 Rock bed The size of the rock bed heat collector box was determined by the amount of rock required for the system. In Table 8, the amount of rock required for the rock bed heat collector is calculated in accordance with Table 2 of Chapter 2. The calculation will be based on a 1m³ space/ room, which requires heat for 12hours per day. Table 8: Total rock required for heat storage. VOLUME OF ROCK REQUIRED AS STORAGE MATERIAL

Description

Imperial

Metric

Heating requirement of space/ room of

968BTU

283 Watt/ hour

1m³ b

Duration for the heat required

12 hours

Storage reserve

0 days

Total heat required (a x b x c)

11 616BTU

3396 Watt/ hour

Bulk storage material (table 1)

100lb/ft³

1601.8kg/m³

Specific heat storage material (slate)

0.18BTU/lb°F

0.658Watt/kg.°C

(table 1) g

Temperature range

70°F

21°C

Heat from storage material (e x f x g)

1260BTU/ft³

22 133.67 Watt/m³

Storage material required (d / h)

9.2ft³

0.26m³

4.4 CONCLUSION According to the calculations in Table 8, a total of 0.26m³ of rock is required to discharge heat to a volume of 1m³ for 12 hours during the night-time. The results will be carried over to Chapter 5 to implement and test the heat storage efficiency of the rock through a pilot study. The full-scale model constructed from the waste and off-cut materials will be utilised in chapters 5 and 6 to test the system's performance in a controlled environment.

PILOT STUDY • Chapter 5: Introduction • Pilot study (Part 1) - Test equipment - Method - Results - Conclusion • Pilot study (Part 2) - Method - Results - Calculations - Conclusion - Alterations and changes

INTRODUCTION

Chapter 5 presents the testing equipment utilised for both the pilot study in Chapter 5 and the main study in Chapter 6. The Chapter focuses on the pilot study conducted to determine the system's efficiency prior to conducting full experiment. The results from the pilot study are presented through a table and graphs extracted from the temperature loggers. After presenting the pilot study results, calculations based on the results are done to confirm the system`s performance and compliance with the South African Bureau of Standards: Part O (2011: 17). The chapter ends with the alterations made to the system to improve its performance. 5.1 PILOT STUDY (Part 1) The pilot study is divided into the following two parts: •

Part 1 of the pilot study will determine the efficiency of the solar air heater before connecting the rock bed heat collector.

•

Part 2 of the pilot study will focus on the performance of the solar heating system when the rock bed heat collector is connected to the solar air heater.

5.1.1 TESTING EQUIPMENT •

BTU (British thermal units) Psychrometer: This testing equipment was used during the experiment to determine the flow speed of the air circulating through the solar air heater and rock bed heat collector. The meter is used to test the airflow in ventilation systems installed in commercial buildings.

Figure 33: Psychrometer (Author, 2021)

•

Data Logger: The data logger is used to track the temperature within a room or space for an extended period. The data logger will track the temperature within the solar air heater and rock bed heat collector. The data from the logger will be extracted and transferred into a graph and table to determine the efficiency of the system.

Figure 34: Data logger (Author, 2021)

The data loggers were calibrated after the study was completed by comparing the room temperature of a standard digital thermometer and a contactless infrared thermometer (on room mode). The data loggers measured 25.7°C, the standard digital thermometer measured 25.7°C, and the infrared thermometer measured 25.9°C. The difference in temperature measured was less than 1% and is deemed to be calibrated correctly compared to alternative devices.

5.1.2 EXPERIMENT METHODOLOGY The experiment was conducted for 24 hours from 30 June 2021 at 6:00 am till 1 July 2021 at 6:00 am. The solar air heater was placed at a 26° angle facing North with full solar exposure. The temperature was measured at the outlet of the solar air heater with a data logger capturing the temperature every hour. A data logger was placed outside the solar air heater to measure the ambient temperature every hour. The airflow speed was measured with a psychrometer at the outlet of the solar air heater. The difference between the temperature measured at the outlet and the ambient temperature will be compared to determine the efficiency of the solar air heater. The airflow speed will be utilised to determine the replacement of fresh air within a room or space.

Figure 35: Solar air heater outlet (Author, 2021)

Figure 36: Complete solar air heater

5.1.3 RESULTS Figure 37 and Table 9 illustrate the temperatures recorded from the solar air heater and the ambient air. Table 9: Pilot study part 1 results TIME

TEMPERATURE AT SOLAR AIR HEATER OUTLET

AMBIENT TEMPERATURE

DIFFERENCE BETWEEN AMBIENT AND OUTLET