Category Archives: EuroSun2008-9


C. Silvi

Gruppo per la storia dell’energia solare (GSES) — Via Nemorense, 18 — 00199 Rome, Italy

E-mail: csilvi@gses. it


This poster presentation aims at introducing to the EuroSun 2008 participants the exhibition “Solar Cities From the Past to the Future: Scientific Discoveries and Technological Developments” opening in Rome in the spring of 2009. Now in its second edition, the first of which took place in 2006 at the Genoa Science Festival, the exhibition will be installed at two prestigious and symbolic venues, the Museum of Roman Civilization and the Central State Archive. In Genoa the message was: for thousands of years, and until just 200 years ago, human beings developed experience in building and operating cities run on solar energy alone. Can this experience be useful in designing the solar cities of the future? Is it possible to return to the use of the sun’s energy for lighting, heating and cooling buildings, for producing electricity, fuels, and construction materials for the cities of a technologically advanced world? The upcoming event in Rome will continue to explore these and other questions. Solar features of models of houses, baths, villas, preserved at The Museum of Roman Civilization, will be highlighted with the heliodon approach. The thesis that future or modern solar cities have their main roots essentially in the past will be reiterated.

1. Introduction

Renewable solar energy — what the sun sends us every day, the driving force of all forms of life on earth, of the winds and the water cycle, the growth of forests and other biomass — has always been, is and will always be the principal energy source on our planet.

All over the world, people used solar energy alone until barely 200 years ago, when fossil fuels — coal, oil and gas (actually fossilized forms of solar energy) — began to gain sway. Like nuclear fuel, these forms of energy are not renewable and eventually will be exhausted.

The use of renewable solar energy is thus an age-old experience marked by fundamental discoveries that made it possible to build cities that ran on solar energy alone, ranging from the discovery of fire, which enabled humans to use the solar energy stored in forest wood and other forms of biomass, to the discovery of agriculture and the birth of the first human settlements. The ancient Greeks’ discovery that streets and buildings can be oriented so as to exploit the sun’s light and heat directly and naturally gave birth to solar architecture. The Greeks’ idea was built upon by the Romans, as codified by Vitruvius in De Architectura, and handed down for centuries.

These discoveries characterize what I would call the primitive or ancient solar age. Though we take them for granted today, they are still of the greatest importance in our daily lives. It’s as if an ancient renewable-solar-energy soul were living on in the cities of our modern world, nearly forgotten and not accounted for

If our forbearers were able to build and run cities with renewable solar energy alone for thousands of years, is it not possible for us to do so in the future? This question was raised explicitly in the 1st edition of the exhibition “Solar Cities From the Past to the Future: Scientific Discoveries and Technological Developments” promoted and organized by the Italian Group for the History of Solar Energy (GSES), and the “Italian National Committee ‘The History of Solar Energy’” (CONASES), a multi disciplinary non profit entity established in 2006 by the Italian Ministry for Cultural Heritage and Activities. The exhibition was held during the Genoa Science Festival at the Doria Pamphilj Prince’s Palace from October 26 to November 7, 2006 [2][3].

Подпись: Fig. 1 . Map of Imperial Rome, showing locations of the major baths, facing south or southwest (From a Golden Thread, by K. Butti and J. Perlin, 1981) Подпись: Fig. 2 . An aerial view of Spello, a typical Italian small town, whose shape and relationship with the surrounding farmland is a reminder of its solar past (Foto G. Reveane, 1993).

The exhibition traced the evolution of the Italian human habitat from antiquity to the present day and with a look to the future. It recounted the changes in cities, architecture and energy and food — supply infrastructure, and the scientific discoveries and technological developments that marked the major stages in their history, for instance the Romans’ introduction of flat window glass 2000 years ago [1].

Visitors to the exhibition at the Prince’s Palace were able to explore solar city past, present and future with the aid of more than 40 posters, various videos, seminars and conferences. A brief video report of the exhibition is available on You Tube [4].

A city of modern or future solar age has its roots in the discoveries and inventions made during the Renaissance and the scientific revolution. One example of the progress made over the past five hundred years is the giant steps taken in the understanding how light works by great scientists such as Galileo, Leonardo, Newton, Huygens, Maxwell, Planck and Einstein. The explanation of the photoelectric effect by Einstein contributed to underscore other aspects of the structure of the atom, the nature of light and the electrical origin of the cohesive forces in molecules and matter. All this has opened fascinating prospects for the use of direct solar energy in the modern or future solar age, from solar cells with efficiency ratings of 50% or more to smart glass and photon solar architecture and city planning.

Will scientific discoveries and technological developments allow us to build the solar city of the future, a city powered solely by solar energy?

A thesis presented in Genoa by GSES and CONASES was that to bring the modem solar city into being we must intelligently combine and integrate the experience gained by the ancient cities — not only in terms of technical know-how, but also of art, culture, relations and communication — with the many solutions made available by the scientific discoveries and extraordinary technological developments of the past two hundred years, especially the most recent decades. In other words, as suggested by Norbert Lechner, “Use the best of the old and the best of the new.” [5]. This thesis will be reiterated in Rome’s exhibition.

The impact of water heating on the overall consumption of electric energy in Brazil

Based on the results from the latest survey, it is estimated that 22.6% of the electric energy consumption of the residential sector is using an electric shower device (Figure 1) which instantaneously heats the water as it flows through it commonly called Instantaneous Electric Shower Device; in turn, this represents about 6% [7] of the electric energy consumption in the whole of Brazil (± 22 TWh).

The graph of the average residential load curve in Figure 2 reveals that it is at peak-hour_ normally between 06:00PM and 09:00PM_ that the use of electric shower as a water heating device is the most widely spread [1].

The value indicated in brackets in the key corresponds to the percentage in electric energy consumption for each domestic piece of equipment.

image002 Подпись: □ Microwaves (0,1%) □ Washing machine (0,4%) □ Iron (2,6%) □ Sound (3,5%) □ TV (9,5%) □ Air conditioner (19,8%) U Electric shower (22,6%) □ Rumination (14,3%) □ Freezer (5,2%) □ Refrigerator (22,1%) image004

The load curve of the Brazilian Electrical System-BES, on a typical day, is shown in Figure 3 [11]. Fig. 2. Residential Average Load Curve (W) Fig. 3. Load Curve of the BES (MW)

These studies about the Ownership and the Utilization of Equipments (Pesquisa de Posse de Equipamentos e Habitos de Uso — PPH in Portuguese) coordinated by PROCEL/Eletrobras, are also meant at qualifying the type of ownership, using a customised questionary but with the same standards of measurement from other research institutes for relevant comparison. Through the careful analysis of the individual answers from end consumers regarding the use of their domestic equipments, it is possible to raise important data about living conditions and socio-economic information for example, as well as about the quality of the electric energy supply as a whole, market changes following the electric energy rationing of 2001, domestic appliances purchasing habits etc.

Table 1 shows a summary of the comparative data from the various surveys ran by PROCEL between 1988 and 2005 about instantaneous electric shower ownership in Brazil: it is clear that the number of households using this device increased over those 17 years.

Table 1. Percentage (%) of Brazilian households with electric shower





















In 2005, 42 % of all residencial electric showers were turned on between 06:00PM and 07:00PM causing the Brazilian Electrical System-BES to reach its maximum level in electric energy demand.

There was also a noticeable change of habits in the first hours of the day. Whilst in 1988, 10% of all households in the country had at least one person using this equipment between 06:00AM and 08:00AM, in 2005 this percentage had increased to 31%. (Figure 4).

Fig. 4. Use of electric shower (typical day)


According to Table 2, the Southern region not only has the highest index in electric shower use as well as the highest average ownership with 1.17 electric shower per household_ way above the national average of 0.89.

Table 2. Average ownership of electric shower per household in unit (2005)













Futhermore, it appears that 21% of all interviewees, by 2005, had already switched electric shower devices for solar heating systems. A new demand is also emerging by means of the efforts of a few Brazilian municipalitiescouncils to integrate within their City Planning Directives the obligation, for all new buildings, to offer solar collectors installation facilities.


PROCEL has been focusing, with partner entities and enterprises, on promoting the technological development of equipments using solar energy for water heating.

The Welsh Housing stock

Error! Reference source not found. shows the main dwelling types in Wales and the percentage of the total housing stock that each type occupies. It can be seen that the semi-detached house is by far the most common residential property type, accounting for 44% of the total housing stock, excluding year 2000 onwards properties. The data in bold type shows the building types modelled in this project. These models can be seen to represent around 50% of the total housing stock. A suitable Case Study of a pre-1919 terrace could not be found, but if we were to model this as well then 66% of the housing stock type would be covered.

No data for post-2000 dwellings

Подпись:Rhodes et al [3] provides greater detail of the housing stock, including physical properties, improvements, etc., but it is clear that a large percentage of the housing stock was built before energy efficiency was a serious consideration.

From figure 1, taken from the Renewable Energy Route Map for Wales [1], we see that the domestic sector accounted for 23% of the total carbon emissions in Wales in 2003. The breakdown between electrical and thermal demand is not known.

For this paper the annual electrical demand for each of the dwellings is taken to be 3090 kWh [8].

Study results

At UL FGG KSKE two studies dealing with the influence of glazing properties on daylight levels and energy balance of a building were conducted. Our primary goal was to find out to what extend lower U value of windows influences daylight levels in buildings. In addition, we monitored energy balance of

buildings (transmission losses and solar gains) and compared benefits and deficiencies (can lower heating energy use compensate lower daylight levels).



□ a:b < 1:2 □ a:b > 1:2 m n = 0,5 □ n = 1,0 □ n = 1,5 □ n = 2,0 □ average change Eav-eq [%] □ average change Qn/Au [%]

Fig. 2: Comparison of change in heating energy demand (Qn/Au) and daylight levels (Eav-eq) on the sample of 27 randomly selected buildings with two variants of glazing. The buildings are classified according to air change rate (n [1/h]), building geometry (length to width ratio) and the number of walls with windows (1,2,3).


In the first study [1] students collaborated in a joint comparative analysis carried out in the framework of seminars at two subjects: Building, Environment, Energy (UL FGG UNI — Construction course, 4th year) and Bioclimatic building (UL FGG VSS — Construction course, 3rd year) in academic year 2006/2007. The study comprised student-selected buildings for which the influence of changed glazing characteristics on internal environment and energy balance of buildings were calculated. The choice of buildings included a wide selection of types and geometries of buildings, from small residential houses, schools and larger public to office buildings (Fig. 1). Random selection of buildings (surface- to-volume ratios were among 0.10 and 1.00) covered current architectural production and ensured that the results were general enough to be statistically valid. For each of the 27 buildings students calculated yearly energy balance in a building (according to EN 832, all at the same location) and daylighting in a room of a chosen building (21. 3., 21.6., 21.9. and 21. 12. at 12:00 under standard CIE overcast sky) for two variants of commercially available window glazing:

1. double glazing, U = 1.40 W/m2K, g = 0.65, tv = 0.70

2. triple glazing, U = 0.60 W/m2K, g = 0.50, tv = 0.50

All the other input data remained the same (location, geometry of building, sizes of windows, U values of non-transparent parts, orientations, etc.). Daylighting calculations were carried out with a computer

tool SPOT1M v3.1 Sensor Placement + Optimization Tool. Heating energy demand according to EN 832 was calculated with computer tool GEnV 1.1.

In the case of 27 student-selected buildings, change of window glazing resulted in the average reduction of specific heating energy demand (Qn/Au) by 14.4%. At the same time the reduction of average illuminance level (Eav-eq) in rooms decreased by immense 25.3%. The reduction of the ratio of heating to daylight is almost 1:2 and is in some cases even higher. For instance, case P17-TS reached 0.7% reduction of heating energy demand and 29.2% reduction of daylight level in a chosen room. Similar result was obtained in case P19-TS where heating energy demand was reduced by 1.5% and the reduction of daylight was 27.8%. Only in three cases (P1-TS, P2-TS and P16-TS) the heating energy demand reduction was higher than the reduction of daylight levels in rooms (Fig. 2).

After students executed calculations of energy consumption and internal illuminance levels in their buildings for both types of selected glazing, they were expected to make a decision on the final configuration of their buildings external envelope in regards to their findings. In the end they had to make an argumented decision whether they were going to use triple or double glazing. In such a way students were encouraged to make an executive design decision on the basis of their own findings (executed calculations of energy demand for heating and internal illumination levels) and knowledge about building physics and internal environment that they accumulated during seminar course and lectures in their respective subjects. With such an approach to seminar work students are not just given information but are expected to use the tools and knowledge at their disposal to come up with the best solution for a certain case on the basis of their own experience. A valuable lesson for future civil engineers is learned — that interventions in one area of building design can influence other aspects of the building as well, and for optimal results a holistic approach is necessary.

Very similar results were obtained in an independent parallel study [2] carried out by the staff of KSKE. We studied a hypothetical single room object 4m x 6m x 2.5m with one south oriented window positioned on the shorter wall, for which we changed size and glazing characteristics. The window size varied from 14% (1/7 — K1 configuration) of floor area, 20% of floor area (K2 configuration), to 42% (glazing of entire wall — K3 configuration) of floor area. Two variants of window glazing characteristics were chosen:

1. double glazing, U = 1.12 W/m2K, g = 0.61, tv = 0.76

2. triple glazing, U = 0.74 W/m2K, g = 0.50, tv = 0.66

The U value of the non-transparent building envelope was U = 0.15 W/m2K. For easier comparison in both studies the same computer tools were used.

As expected, the analyses showed distinctly negative influence of triple glazing on daylighting of spaces compared to double glazing. Surprisingly, use of heating energy was minimally reduced when triple glazing was used. Energy balance of the K1 configuration with the smallest window opening (Az = 1/7 of floor area) was almost the same if double (Qn/Au = 68.33 kWh/m2a) or triple glazing (Qn/Au = 67.80 kWh/m2a) was used. The difference was only 0.78 %. At the same time the illuminance level (Eav) fell by 13.1 % when triple glazing was used. The reason for small differences of energy demand is the g factor and decreased solar gains (Qs), which are 18% lower when triple glazing is used, but the transmission losses (Qt) are reduced by only 9.2% (Fig. 3).

The actual values of heating demand reduction and illuminance levels deterioration differ compared to the first study, but the ratio between them is identical (when triple glazing is used, daylighting level is reduced by a factor 2 regarding heating energy demand). The results of both studies show a trend of extreme deterioration of daylighting in buildings and relatively small reduction of heating energy demand when triple glazing is used.

In the third configuration (K3 — window size is 42% of floor area) the size of glazing is 20% of the entire fa? ade area, which, compared to the first configuration, presents three times larger window area. As expected, transmission losses dramatically increase and double glazed configuration has 17.4% higher losses than the triple-glazed one. Regarding solar gains the situation is reversed; in the case of triple glazing the gains are 18.8% lower. In the context of the entire building heating energy demand is

by 7.0% higher when double glazing is used, but at the same time the average illuminance level is reduced by 14.6% (Fig. 4).

It is obvious that major part of heat losses originate from ventilation, when well insulated non­transparent envelope (U = 0.15 W/m2K) and quality glazing (U = 1.12 W/m2K, g = 0.61, tv = 0.76) are used. In the first configuration with double glazing 57 % of the entire heat losses belong to ventilation losses (Qv).

Reducing U value of glazing in buildings, which have 10% — 20% of glazed fa? ade area in the present state-of-art is not reasonable. The quantity of transmitted daylight disproportionally decreases compared to heating energy demand. Furthermore, the reduction of g and Tv factors has negative impact not only on solar gains and daylighting, but also on health and use of energy for electric lighting. Especially prolonged use of artificial lighting is the factor that additionally speaks in favor of window glazing with higher visual and solar transmittance.

2. Conclusion

Students collaborated in joint comparative analyses of the presented problem. They used 27 randomly selected buildings of various building types (small residential buildings, schools, and larger office buildings), geometries and configurations. For each building they calculated yearly daylighting under standard overcast CIE sky and heating energy consumption according to EN 832. The buildings were glazed with two variants of glazing systems (double glazing: U value 1.40 W/m2K, g = 0.65, tv = 0.70 and triple glazing: 0.60 W/m2K, g = 0.50, tv = 0.50). All other input data remained the same. The average of 27 buildings showed that by changing double-glazing for triple glazing heating demand of buildings reduced by 14.4%, but at the same time it deteriorated daylight levels in the reference rooms by dramatic 25.3% (Fig. 1). The proportions between the heating reduction and daylight levels were in some cases even more drastic and reached close to 50% of daylight reduction. Only in 3 cases the reduction of heating energy demand was larger than the reduction of daylight levels. A parallel analysis that was carried out independently, as an internal study at KSKE, showed similar results.

Both analyses showed the trend of drastic reduction of daylight levels in the reference rooms and at the same time small or even in some cases negligible improvement of the heating energy balance. The study showed that in moderate climate at the moment the technical maximum is double glazing with U value in the range of 1.1 W/m2K and transmissions about tv = 0.76 and g = 0.61. Both values are given for clean glass and perpendicular incidence angle. In reality we have to allow for correction factors and can expect even more evident differences. Daylight represents a very important element of wellbeing of users and directly influences the amount of electrical energy used for artificial lighting. At the same time lower g value reduces the possibility of solar heat gains. Considering the present characteristics of commercially available triple glazing we can justly ask ourselves, if wide use of such glazing can be justified.


[1] A. Krainer, M. Kosir, Z Kristl,. Analyses of glazing characteristics influence on internal environment in 27 randomly chosen buildings — partly realized by the students in the framework of the seminars Building — Environment-Energy (UL FGG UNI — construction, 4th year) and Bioclimatic buildings (UL FGG VSS — construction, 3rd year), UL FGG KSKE; 2007.

[2] A. Krainer, M. Kosir, Parametrical study of U value influence on daylghting and energy balance of a hypothetical one-space building — internal publication, UL FGG KSKE; 2007.

[3] A. Krainer, M. Kosir, Z. Kristl, M. Dovjak, Passive house versus bioclimatic house. Gradbeni vestnik letnik 57 (2008) 3, 58-68.

[4] L. Heschong, Windows and Classrooms: A Study of Student Performance and the Indoor Environment. Fair Oaks, Heschong Mahone Group. California Energy Commission, 2003.

[5] L. Heschong, Windows and Offices: A Study of Office Worker Performance and the Indoor Environment. Heschong Mahone Group. Fair Oaks, California Energy Commission, 2003.

. The 2nd edition of the of the Italian travelling exhibition on Solar Cities From the Past to the Future

The installation designed for Genoa has been completely revised for Rome, where there will be a much larger display space, longer opening time, site-specific models and documentation. In parallel to the exhibition, as in Genoa, a series of conferences, seminars, debates and shows will also be held. Details will be published in the fall.

2. The Exhibition at Museum of Roman Civilization

Подпись: Fig. 5 . Solar Architecture: Model of a Roman Hospital (courtesy of the Museum of Roman Civilization). Подпись: Fig. 6 . Archeological remains (Frigidarium) of 3 the Baths of Trajan and Hadrian, Cyrene, Libya.

The Museum of the Roman Civilization is a unique venue for an exhibition on solar energy. The two sections, historical and thematic, present a synthesis of Rome’s history, from its origin to VI century B. C., and the various aspects of Roman expansion. It holds a large collection of reproductions and models that illustrate the history of the formation of the city of Rome and of the Empire, as well as the use of sun’s energy in hospitals, villas, baths, etc. [6][7].

The solar features of these buildings will be illustrated by the use of a heliodon, which will reproduce the sun’s path in various moments of the day as well as different seasons.

Energy Efficiency and solar heating systems in Brazil

According to data from the Brazilian Association of Heating — ABRAVA in Portuguese [9], there was an increase in the sales of solar collectors in 2001 reaching 480,000 m2 _ way above the average of previous years. However, sales fell down in the following years to an average 350,000 m2 per year. Whereas countries like Austria and Greece attend up to 12% and 22% of their population respectively [10], with solar thermal energy, Brazil’s index doesn’t even reach 1%.

In order to understand better the current situation, it is important to take into consideration the high initial cost of installing solar systems in comparison to the much lower cost of acquiring an electric shower device in addition to how easy the latter is to install. These three factors represent a serious barrier to the growth of the solar energy market in Brazil.

As an example: a low-cost solar system, sold over the Internet [11] and made of PVC with only two solar collectors and a storage unit of 200 liters, has a price tag of about €400 excluding installation costs. The price tag of another equipment made of metals, subsequently offering better results, can reach double this value. In Brazil, one can easily buy an instantaneous electric shower device of 5,400 Watts for about €10 [12] with no extra installation cost as it is a quick and easy “Do It Yourself — DIY” job.

Another current barrier, is the absence, in some big Brazilian cities, of specialized companies or professionals to install the solar equipments as well as to maintain them.

The partial results of an on-going nationwide study, coordinated by PROCEL in partnership with Papal Catholic University-Minas Gerais (PUC-MG in Portuguese), point out the existence of a €40,000 solar water heating system for a gym’s swimming pool in a residential area of Rio de Janeiro which started causing problems ever since it was installed back in 2006. The company it was bought from still hasn’t been able to offer a practical solution for it to work properly and thus the use of the system was switched to a system using natural gas.

These examples indicate the delay of solar heating systems in penetrating the Brazilian market. Considering that 81.5% of all Brazilian households heat water to take showers, 90.8% of the time it is using electric energy while only 7.3% of the time it is using natural gas [4].

In 2000, as one of its main lines of action and within its solar energy heating dissemination strategy, PROCEL launched its awarding process of the PROCEL Energy Saving Seal (Figure 5) to solar collectors and thermal tanks in association with the National Institute of Norms, Measurements and Industrial Quality — INMETRO in Portuguese [13].

Fig. 5. PROCEL Seal


The purpose of PROCEL Seal is to stimulate the national production of more efficient equipments and domestic appliances giving consumers information and guidelines in order to buy more energy efficient equipments thus contributing towards technological development and the reduction of the environmental impact.

The PROCEL Seal is annually awarded to equipments with the most efficient indexes of energy efficiency, in its respective category, usually characterized with an “A” at the top of the National Energy Conservation Label — ENCE in Portuguese (Figure 6). Please note that for a couple of specific product categories, further technical and qualitative features are required of the equipments, to be checked and considered towards the awarding of the PROCEL Seal. (Example: the proven electrical safety of the equipment).

In order to be awarded the PROCEL Seal, the product is submitted to various technical tests run by impartial and competent labs indicated by PROCEL. The adhesion of the producing companies for labelling, to this day, is volunteered.

While at its beginning, the program counted only two participating product manufacturers, in 2007, 160 types of solar collectors were listed from 29 different manufacturers [13], representing more than 50% marketshare.

The PROCEL Seal has been awarded to solar collectors since 2000 thus contributing to the significant improvement of the performance of those currently available on the market.

Figure 7 shows the evolution of the average monthly production of specific energy from solar collectors for shower water heating between 2000 and 2007, for all collectors labelled by the INMETRO as well as those awarded the PROCEL Seal.


Procel Seal Average ENCE

Fig. 7. Evolution of the average monthly production of specific energy from solar collectors

(kWh/month per m2)

Whilst the PROCEL Seal has been awarded to the thermal tanks of solar heating systems since 2002, these equipments have already been receiving the ENCE label since 2001. Until 2003 there were no difference in the criteria required for the awarding of the PROCEL Seal and the ENCE label. However, from that year onwards, distinctive indexes were established in relation to the specific loss of monthly energy for both of them, to be consistent with the PROCEL Seals indexes which are constantly upgraded.

Figure 8 shows the evolution of the specific loss of energy’s monthly average of 200 liters thermal tanks labelled between 2001 and 2007. The curve points out to the significant improvement of these equipments’ performance and available on the market over the years.


Fig. 8. Evolution of the specific loss of energy’s monthly average in thermal tanks


In 2000, the university PUC-Minas Gerais and PROCEL, in partnership with the City Council of Contagem (Minas Gerais), took part in a project to install 100 solar water heating systems with a capacity of 200 liters each. This project was the largest of its kind in terms of the ratio scale/number of households, in Brazil. It also provided valuable data which allowed for the addition of solar heating systems on the list of electric energy utilities’energy efficiency projects thus meeting the National Agency of Electric Energy’s (ANEEL in Portuguese) legal requirements_ a compulsory investment of 0.5% of these companies’net income.

The Contagem’s Project corroborated an average reduction in electric energy consumption of up to 40%, depending on the type of heating systems installed, proportionate to savings of up to 60% in utility bills [14]. This project has demonstrated the financial viability of the use of solar heating systems for the lower-income population. Based on these results, the Electric Energy Distribution Utility of Minas Gerais (CEMIG in Portuguese) stimulated a number of this kind of projects which turned the state of Minas Gerais pioneer in the use of solar systems nationwide.

In 2005, PROCEL, in the context of PEE, acquired equipments to expand the technical capacity of the University PUC-MG’s Solar Laboratory which is responsible for testing solar collectors towards the ENCE and the PROCEL Seal labelling process. This technical expansion, thanks in particular to a solar simulator imported from Germany, allows for most of the tests to be ran indoors by the laboratory thus speeding up the overall process_ from a month to less that a week_ reducing the impact of the weather condition. This equipment is the first of its kind in the whole of Latin America out of 5 in existence in the whole world and it cost USD 500,000, donated by GEF (Figure 9).

In the same way, the Laboratory at the Technology Research Institute in Sao Paulo (IPT in Portuguese) benefited from PROCEL’s help in acquiring new equipments for tests on thermal tanks with the same positive effects.

There are various ongoing studies being carried out to demand the labelling of all solar collectors and thermal tanks with ENCE. However, to become compulsory, this process needs to clarify policies as well as to provide the minimum energy efficiency indexes to be indicated as established by the law #10.295 of 2001 [15], also known as “Energy Efficiency Law”. These initiatives will empower the sector to generate new mechanisms to further advance the quality of solar heating equipments.

In this context, the carrying out by PROCEL, in partnership with PUC-MG, of the studies mentioned earlier represent a new step since they are destined for the accurate assessment of solar heating systems’ installations found in Brazil today be it in: the residential sector (showers and swimming pools), the service sector (hotels, gyms and schools) or the industrial sector. Involving about 60 professionals such as university professors, researchers, consultants and scholarship holders from various large Brazilian cities such as Belo Horizonte, Rio de Janeiro, Porto Seguro, Brasilia, Campinas, the nationwide project’s main objective is to lay the strategic plan towards further technical development and dissemination of the solar energy in Brazil.

2. Conclusion

As the studies carried out by Eletrobras/PROCEL (PPH) have shown, the use of electricity is predominant for water heating amongst Brazilian households due to the overwhelming presence of electric showers as the device most commonly used for this purpose. The immediate consequence of this fact is reflected in the inflated demand during the electric system’s peak-hour.

It has been asserted that the consumption of electric energy for water heating in Brazil is overall considerably high and historical data is pointing out at an ongoing growth trend should no provision, whether political or technical, be made rapidly for this sector.

Thus, the use of solar energy for water heating in Brazil has huge growth potential since less than 1% of the population currently makes use of this type of energy. Taking these facts into consideration and notwithstanding the favorable climate in the country, with approximately 2,200 hours sunshine per year [10], one can assert that the most recommended alternative for this end use is to substitute the electric shower with alternative sources of energy such as solar energy. In this context, PROCEL has been achieving a series of carefully planned and controlled activities towards the dissemination and the stimulation in the use of solar heating systems in Brazil. These activites can count on the collaboration of significant business partners such as INMETRO, PUC — MG, IPT, ABRAVA as well as the Manufacturers’Association. These partnerships are essential to

reach the results sat through our objectives. One of PROCEL s main lines of action has been the structuring of the testing laboratories supporting ENCE and the PROCEL Seal’s labelling process.

Since the use of solar heating systems is not recommended in all regions nor all conditions, there are constant efforts made by manufacturers, laboratories and PROCEL itself not only to contribute to the overall improvement in the efficient consumption of electric energy, but also of water and electric safety in water heating electric equipments. Indeed, these equipments were amongst the first to be considered for labelling with ENCE. Despite all of these combined effortst and the results shown by the success of the projects already running, there is still a long way to go in order to encourage nationwide the expansion of the use of this water heating technology: one of the most important step is to add it in the financing program of popular housing.

Water heating solar equipments are currently being taken into consideration by the Ministry of Mines and Energy (MME) to be added to the existing energy efficiency law. This should be implemented as of the year 2009 which will represent a true landmark in the sector’s advances.


[1] PROGRAMA NACIONAL DE CONSERVACAO DE ENERGIA ELETRICA-PROCEL. Available at <http://www. eletrobras. com/procel.>.

[2] CENTRAIS ELETRICAS BRASILEIRAS-ELETROBRAS. Available at <http://www. eletrobras. com>.

[3] PROGRAMA NACIONAL DE CONSERVACAO DE ENERGIA ELETRICA. “Relatorio de Avaliagao de Resultados: Ano 2006”. Rio de Janeiro: Eletrobras, 2007. Available at: <http://www. procelinfo. com. br>. Accessed on: 15th of Dec. 2007.

[4] PROGRAMA NACIONAL DE CONSERVACAO DE ENERGIA ELETRICA. “Avaliagao do Mercado de Eficiencia Energetica no Brasil: Pesquisa de Posse de Equipamentos e Habitos de Uso da Classe Residencial no Ano Base 2005”. Available at: <http://www. procelinfo. com. br>. Accessed on: 15th of Sept. 2007.

[5] WORLD BANK. Available at <http://www. worldbank. org>. Project ID P039200. Accessed on: 17th of Sept. 2007.

[6] SOUZA, R. “Pesquisa de Mercado em Eficiencia Energetica”. Rio de Janeiro: Apresentagao dos Resultados, April 2007. Available at: <http://www. procelinfo. com. br>. Accessed on: 15th of Sept. 2007.

[7] EUROPEAN COMMISSION. “Market Study on Development of the Thermal Solar Market in Brazil”. Bruxelas: European Communities, 1999.

[8] OPERADOR NACIONAL DO SISTEMA ELETRICO (ONS). “Curva de Carga”. Available at: <http://www. ons. org. br>. Accessed on: 17th of Sept. 2007.

[9] FARIA, C. ABRAVA. “Aquecimento Solar”. Rio de Janeiro: Palestra na Camara de Vereadores do Rio de Janeiro, December 2006.

[10] RODRIGUES, D.; MATAJS, R. “Um banho de sol para o Brasil: o que os aquecedores solares podem fazer para o meio ambiente e a sociedade”. Sao Paulo: Vitae Civilis, 2005.

[11] LOJAS AMERICANAS. Available at: <http://www. americanas. com. br>. Accessed on: 24th of Oct. 2008.

[12] CASA & VIDEO. Available at: <http://www. casaevideo. com. br>. Accessed on: 24th of Oct. 2008.

[13] INMETRO. “Tabelas de Consumo de Energia Eletrica”. Available at: <http://www. inmetro. gov. br >. Accessed on: 17th of Sept. 2007.

[14] PEREIRA, E. “Aquecimento Solar de Agua para fins sanitarios”. Rio de Janeiro: Palestra na Camara de Vereadores do Rio de Janeiro, December 2006.

[15] AGENCIA NACIONAL DE ENERGIA ELETRICA-ANEEL. Available at <http://www. aneel. gov. br>. Accessed on: 17th of Sept. 2007.

Modelling the Welsh Housing stock

Computer Thermal Modelling using TRNSYS [9] and ECOTECT [10] software programmes provided an estimate of the thermal demands in the dwelling types modelled, as well as the potential carbon savings achievable through changing the heating, cooling and DHW demands from being primarily met by natural gas to primarily met by Solar Thermal. An existing dwelling was chosen to be representative for each of the housing types highlighted in Error! Reference source not found. and was then physically surveyed in detail [3]. Each dwelling was then modelled in ECOTECT before exporting the physical details into the TRNSYS simulation software to undertaken the energy demand assessments.

Подпись: Figure 2. ECOTECT model of house type 3

Only 12 out of the 13 housing types have been modelled to date — the most recent house type has not yet been modelled. The ECOTECT model for the largest dwelling, house 3, is shown in figure 2 as an example of the modelling undertaken. This image shows how the Solar Thermal collectors have been arranged for this property for the purposes of assessing the potential solar yield.

Table 2. Predicted annual energy demands for electricity, space heating, space cooling and domestic hot water


Dwelling type



Elec Use (kWh) (kWh/m2)

Space Heating (kWh) (kWh/m2)

Space Cooling (kWh) (kWh/m2)







Pre-1850 Detached House











Pre-1850 Converted Flat











1850-1919 Semi Detached House











1920-1944 Semi Detached House











1945 — 1964 Low-rise Flat











1945-1964 Semi-detached House











1965-1980 Detached House











1965-1980 Mid-terrace House











1981-1999 Low-rise Flat











1981-1999 Mid-terrace House











2000-2006 Semi-detached House











Post-2006 High-rise Flat










Table 2, taken from Ampatzi [5], presents the main details and findings of this thermal

modelling. This

version has been amended to include m2 figures for each dwelling as well as electricity demands.

It can be seen that the dwellings thermal demand generally reduces per m2 as their construction date gets closer to the present day. It can also be seen that the internal gains from electricity use also become more important in the overall energy balance as the houses become newer. There are anomalies as would be expected from Case Studies — in particular House 1 which is explained by it being a very energy efficient refurbishment. Interestingly, this house compares very favourably with House 11 built to 2000 regulations, showing the potential for bringing old housing stock back into use.


A. Lalayan1* and V. Afyan2

1 SolarEn, LLC, 2/2 Shrjanayin Str., Yerevan 0068, Armenia

2 SolarEn, LLC, 2/2 Shrjanayin Str., Yerevan 0068, Armenia

* arthur lalayan@solaren. com


This article discusses the need to meet the challenges in renewable energy development in Armenia through comprehensive education. These challenges require going for changes in perception of the reality related to the stage of technological development and future energy demand taking into account scarcity of the organic fuel and environmental implications of the traditional energy sources. This applies from generation to consumption, and from planning to education in general. Renewable energy education is imperative for Armenia. It should start from schools but also involve and be comprehended by public and statesmen. Introductory classes in schools and both no-degree and degree classes in universities, public awareness and decision-makers training programs will help in understanding and utilizing the country’s indigenous and sustainable energy resources.

Keywords: Renewable energy, Armenia, education

1. Introduction

Both developed and developing countries need in state support to promote renewable energy technologies as sustainable energy solution for tomorrow. In this respect education and public awareness of not only technical aspects but also benefits the renewable energy can offer to general public and to the state is crucial.

The energy sector of Armenia was integrated in unified energy system of the former Soviet Union, during which cheap energy was available to population. Currently, the country is heavily dependent on imported fuel (natural gas and nuclear fuel). To enhance country’s energy security and reduce dependence on foreign supplies Armenia needs to develop its own renewable energy resources.

These challenges require going for changes in perception of the reality related to the stage of technological development and future energy demand taking into account scarcity of the organic fuel and environmental implications of the traditional energy sources. This applies from generation to consumption, and from planning to education in general. A number of programs to promote renewable energy in Armenia were implemented since mid 1990s, and only limited disciplines within the general power engineering programmes incorporate basics knowledge in renewable energy. Education and public awareness projects included small scale publications for general public and workshops or seminars under donor funded projects. An introductory and non­mandatory renewable energy classes are incorporated in very few universities’ curricula. However, this is not enough to get public accept and adopt renewable energy in their lives. Adoption of new technology will require new knowledge, skills and change in mentality. Spreading the word becomes crucial, preaching and teaching — imperative.

The exhibition at the Central State Archive

At the Central State Archive, documents from public and private archives will be on display in an area of 600 square meters to recount the efforts made by the pioneers of the 19th and 20th centuries in order to achieve with solar energy the same things accomplished with fossil and nuclear fuels, i. e. heating and cooling buildings, illuminating day and night living and working spaces, powering farms, industries and other human activities.

Gaetano Vinaccia (1889-1971), an architect and city-planner, is the author of dozens of little known publications and articles on solar urbanism and architecture. Among them is the 385 page book “Il corso del sole in urbanistica ed edilizia” (“The path of the Sun in urban planning and building construction”), published in 1939 in which Vinaccia reviewed systemic architectural and city-planning aspects of the use of solar energy over the ages, in the conviction that the past has to be placed at the centre of any enterprise headed for the future [8][9].

Giovanni Francia (1911-1980), a mathematician and engineer, thought that solar heat, abundant at low density and temperature, needed to be collected at high temperatures in order to be useful in modern societies to run industries and power plants. He was the first person ever to apply the Fresnel Reflector Technology principle in real systems, linear, in Marseille in 1963, and point focus, in S. Ilario in 1965. He envisioned a modern city powered only with solar energy. In 1970, before the 1973 oil crisis, working with two young architects, Bruna Moresco and Karim Armifeiz, and other collaborators, Francia developed a visionary project for a model energy-independent city, with a population of about 100,000 that would rely on solar energy. He called it "The solar city — Hypothesis for a new urban structure [10][11]."

Подпись: Fig. 8 . Two different approaches, vertical and horizontal, offering the same living space, Gaetano Vinaccia (1889-1971), “For the City of Tomorrow” [8][9]. Подпись: Fig. 7 . Model of a solar powered city presented by Giovanni Francia (1911-1980) in Nice (France) in 1970 [10] [11].

Francia was one of the first people in modern times, if not the very first, to propose the idea of the solar city so explicitly. It was precisely because of this pioneering intuition of Francia’s that GSES and CONASES decided to organize the 1st Solar Cities exhibition in Genoa, and to honour him with a 20-minute DVD [12]."

In Rome new documents and pictures on the Solar city project preserved in Brescia in the Francia Archive will be on display.

At the venue of the Central State Archive highly visible projects of solar buildings and cities headed for the future, selected either from Italy or from other countries, will be exhibited as well.

6. Conclusion

The "Italian Solar City Travelling Exhibition" is part of the “Italian National Solar Energy History Project” whose purposes are first and foremost cultural. It aims at changing the perception people have about solar energy and at envisioning that it is possible to combine the knowledge of the past, as recommended by Vinaccia, with the introduction of the most advanced solar technologies, as those pioneered by Giovanni Francia, on a large scale in a modern or future city [13].

The special symbolic environments offered by the Museum of Roman Civilization and the State Central Archive, should contribute in addressing the scientific challenges and research directions toward either the past or the future, in order to use the best of both as suggested by Norbert Lechner. The exhibition will show how to rethink our future energy infrastructure and its technological, organisational and cultural implications. How to supply solar-generated electricity, heating and cooling to homes, hospitals, schools, industries and offices, for transportation and other economic activities. It will especially focus on the importance of solar light and heat, as directly available in nature, for day lighting, heating and cooling buildings, that are the greatest consumers of energy in modern cities.

6. Acknowledgements

In writing this paper I had the benefit of accounts from and contacts with many people. I would like to thank in particular, C. F. Giuliani, M. Martelli, R. Merola, G. Nebbia, P. P. Poggio, L. Ungaro, U. Wienke and the heirs of G. Francia, and G. Vinaccia.


[1] K. Butti, J. Perlin, Solar Houses and Cities in the Ancient Mediterranean, Sapere 2006; www. gses. it 2008.

[2] C. Silvi, S. Los, The Italian Solar City Travelling Exhibition, Poster Presentation, Proceedings International Solar Cities Congress, Oxford, 2006; www. gses. it 2008.

[3] C. Silvi, Prima edizione a Genova della mostra su storia e futuro dell’energia solare nelle citta (First exhibition in Genoa on the history and future of solar energy in cities), Scienza e Tecnica, December 2006; www. gses. it.

[4] Videoclip, Le citta solari al Festival della Scienza di Genoa (Solar Cities at the Genoa Science Festival), You Tube 2006; www. gses. it/conases/genova. php.

[5] N. Lechner, The Future of Architecture: Sustainable Architecture, Lecture delivered in China in 2007 (private communication).

[6] L. Ungaro, Perche una mostra su mostra sull’energia solare al Museo della Civilta Romana: sinergie possibili (An Exhibition on Solar Energy at the Museum of Roman Civilization; Possible Synergies),

Seminar “I pionieri dell’energia solare incontrano le nuove generazioni (Solar energy pioneers meet new generations)”, Rome (Italy), April 4, 2008; www. gses. it 2008.

[7] C. F. Giuliani, Evidenze archeologiche e fonti storiche per la riscoperta dell’uso dell’energia solare in alcuni ambienti costruiti nell’antichita (Archeological Evidence and Historical Sources for Rediscovering Sun’s Energy Use in the Built Environment in Antiquity), Seminar “I pionieri dell’energia solare incontrano le nuove generazioni (Solar energy pioneers meet new generations)”, Rome (Italy), April 4, 2008; www. gses. it 2008.

[8] G. Vinaccia, Per la citta di domani (For the City of Tomorrow), Fratelli Palombi Editori, Volume II, Roma, 1943 — 1952.

[9] C. Silvi, The work of Italian solar energy pioneer Giovanni Francia (1911 — 1980), Proceedings ISES SWC 2005, Orlando, Florida (USA); www. gses. it 2008.

[10] Nice-Matin, L’utilization industrielle de la ‘houille d’or’ premier pas vers les (futuriste) villes del soleil, Vendredi 9 Octobre 1970.

[11] G. Francia, Solar City Project — Hypothesis for an Urban Structure, Proceedings COMPLES meeting, Marseilles, Bulletin 19, April 1971.

[12] C. Silvi, R. Torti, L. Francia, DVD ‘Giovanni Francia’s Contribution to the Idea of a Solar City’, Oct. 2006.

[13] C. Silvi, The Italian National Solar Energy History Project, Poster presentation, Proceedings of ISES Solar World Congress 2007, Bejing (China), Sept. 18-21, 2007.

Study Performances of Thermosyphon with Heat Source near the Top and Heat Sink at the Bottom

E. Yandri1* N. Miura1, T. Kawashima1, T. Fujisawa1, M. Yoshinaga2

1Solar Energy Research Group, Department of Vehicle System Engineering, Faculty of Creative Engineering,
Kanagawa Institute of Technology, 243-0292 Atsugi, Japan

2Department of Architecture, Faculty of Science and Technology, Meijo University, 468-8502 Nagoya, Japan

Corresponding Author, vandri@,ctr. kanagawa-it. ac. jp

Solar energy can be converted into electricity with Photovoltaic cells and to heat with solar collectors. Especially for solar collectors, the heat collected can be utilized for both water heating and space heating applications. Solar collector researches for space and water heating has been developed and resulted many interesting designs, from simple thermosyphon systems with low maintenance to automatic operation systems which are depended so much with mechanical and electrical properties like pumps, valves, sensors, etc. Recently, a device which transfered heat from the hot reservoir near the top to the cold reservoir at the bottom was invented by Ipposhi et. al [6], called as the ITMI model. As same as the ITMI model was constructed and tested. We improved the ITMI model by proposing the IMT model. The first report was presented in SWC 2007 by comparing the performance of ITMI model and IMT model. The current experiments are completed with a digital flow mater of vapor in order to be able to calculate the heat energy transported. Some experimental parameters are varied in order to know the optimal operating condition for this IMT model. Heat input is varied for 100, 200, and 300W. Inclination angle between evaporator and top heat storage is varied for 0, 5, and 100. Level of heat store in the top heat storage are varied for 20, 110, and 200mm. Result shows that this IMT model can work better for all heat input (100, 200, 300W), and for all heat store in the top heat (20, 110, and 220mm) with inclination angle of 00, 50, 100. This model could be more interesting for water and space heating applications as more ecological approach.

Keywords: natural circulation, thermosyphon, solar energy

1. Introduction

Solar energy can be converted into electricity by Photovoltaic cells, heat by solar collectors, and both electricity and heat by hybrid photovoltaic and thermal (PV/T) panels. The collected heat can be used for Space Heating and Solar Water Heating (SWH). A typical SWH system is a combination of solar collectors, an energy transfer system and a thermal storage system. SWHs are also characterized as open loop system (direct) which circulates potable water through the collectors and closed loop system (indirect) which uses antifreeze heat-transfer fluid such as polypropylene glycol to transfer heat from the collector to the potable water in the storage tank [2]. Depend on the way to circulate the working fluid, SWHs are divided into active system which uses a pump to circulate the working fluid such as water or polypropylene glycol through the collectors and passive system which circulates the working fluid naturally by the effect of the gravitational force [2]. The passive system calls also thermosyphon which means the heat transport device that can transport a large amount of heat using body forces (gravitational and centrifugal forces). Thermosyphon has a great advantage because of no electrical energy and simple structure. That is why, the thermosyphon researches are not intended for SWH application only, but for many applications. Thermosyphon was studied as an alternative liquid cooling technique in which heat is transferred as heat of evaporation from evaporator to condenser with relatively small temperature difference [3]. Thermosyphon radiator used for domestic and office heating was studied and its performance has been tested with Freon 11, acetone, methanol and water as working fluid [1]. A model of the two-phase flow and heat transfer in the closed loop two phase thermosyphon (CLTPT) involving co-current natural circulation, which is focus for electronics cooling that exhibit complex two-phase flow patterns due to the closed loop geometry and small tube size [4]. The main reason to develop a thermosyphon with a heat source near the top and heat sink at the bottom is to solve weight problem when a thermosyphon installed on the roof [7].