NEW CONCEPT OF SOLAR AIR HEATER INTEGRATED IN THE BUILDING
J.L. Canaletti, G. Notton, C. Cristofari
University of Corsica - UMR CNRS 6134 Scientific Research Center of Vignola, Route des Sanguinaires, F-20000 Ajaccio, France Telephone: 33.4.95.52.41.52, Fax: 33.4.95.52.41.42, E-mail: gilles,notton@univ-corse,fr
Received: 6 Sept 2007; accepted: 11 Oct 2007
We present a new solar air collector totally integrated in a shutter. The air is moved by a fan provided in electricity by a PV module, this air pass a first time in the cover then between the cover and the absorber, and is injected in the house, this solar shutter is reversible and can run in all positions, The concept of this new solar air heater is described in this article and the experiment is presented.
Keywords: solar buildings
Organization(s): Technical Institute of University of Corsica. Experience: Engineer (1991-1997), Teacher (1997-2007).
Main range of scientific interests: solar energy, renewable hybrid systems, thermal solar systems. Publications: 1 international publication and 6 Conference papers.
Jean-Louis Canaletti
Organization(s): University of Corsica, Assistant Professor.
Experience: ERASME, Engineer (1994-1998), Director of Technology incubator (1998-2002), Technical Institute of University of Corsica (from 2002).
Main range of scientific interests: solar radiation, renewable hybrid systems, thermal solar systems. Publications: more than 20 international publications and 50 conference papers.
Christian Cristofari
Organization(s): University of Corsica, Assistant Professor empowered to supervise research. Experience: EI, Engineer (1989-1992), ERASME, Engineer (1993-1994), Technical Institute of University of Corsica (from 1994), Chief scientist (2004-2006), Responsible of the ADEME French research network with eastern and central european countries in renewable energies (from 2005). Main range of scientific interests: Solar radiation, renewable hybrid systems, thermal solar systems. Publications: more than 30 international publications and 50 conference papers.
Gilles Notton
Introduction
There's no doubt that the fossil energy resources of our Earth are being decreasing and that the strong economical development of the developing countries as China or India will increase the resources drop. In the other hand, it appears that the massive utilization of fossil fuels (and nuclear ones) endangers our Environment.
The part of the used energy for building is very important and hasn't stopped increasing; to limit or to reduce this building energy consumption, it is necessary to develop some actions concerning the rational energy management in parallel with the utilization of renewable energy sources. The decreasing of the energy consumption in abodes should not be realized to the detriment of the life quality of its occupiers and mainly of their health.
Международный научный журнал «Альтернативная энергетика и экология» № 5 (61) 2008 © Научно-технический центр «TATA», 2008
We present a new patented concept of solar air heater totally integrated in a shutter and able to produce with a total autonomy hot air from sun radiations and to introduce it inside the house. It allows conserving the integrity of the architecture of the house of the building.
Problems of the energy consumption in France
The residential and tertiary sector is the first energy consumer in France (Fig. 1) with 71 MTOE in 2006 [1] i.e. 43.83 % of the total final energy. The green house gases produced by this sector in 2000 are estimated at 119 MT of CO2 (25 % of the total emission). The part of the residential
and tertiary sector stays stable (around 42-43 %) but in absolute value, the energy consumed in this sector increase. The total energy consumption of the building sector increased of about 50 % during these twenty last years with a high penetration of electricity (+130 %) which covers 40 % of all the needs whose 50 % for captive use as lighting, domestic appliances, etc...). The final consumption in the residential sector in 2002 corresponds to 452 TW-h and 100 TW-h for wood energy. The repartition of the consumption by type of use for a main home (i.e. 83 % of the total of the housings) is: 69 % for heating, 12 % for specific use of the electricity, 11 % for water heating and 7 % for cooking.
w o
180 ■ 160 ■ 140 ■ 120 ■ 100 80 ■ 60 40 20 0
D Transport D Agriculture D Residential-Tertiary D Other Industries ■ Iron and Stell Metallurgy
42.1
% 41.0
%
41,86%
4126% 42,41% 42,86%
III
43,48% 43,8
%
I I I I I
1973 1979 1985 1990 2000 2004 2005 2006 Fig. 1. Final energy consumption by sector in France [1]
Fig. 2. Renewable energy production by type in France (2006) [1]
International Scientific Journal for Alternative Energy and Ecology № 5 (61) 2008
© Scientific Technical Centre «TATA», 2008
Moreover, for housings built before 1975 (65 % of the total of the housings), we can estimate that 50 % have been thermally rehabilitated but it stays some energy economies to realize in these housing which have an energy consumption higher than in new buildings. The final energy in the tertiary sector, with 29.2 MTOE increases of more than 25 % in 15 years due to particularly the multiplication of specific uses of electricity as office automation and lighting. We note a high and increasing part of the energy in building of residential or tertiary type; the heating is the more energy consumer. Improving the energy efficiency in building is a research and development domain very important and has a very good future. The utilization of renewable energies to participate to the improvement of the energy efficiency in Building is very important. In France, the part of renewable sources in the energy production is still very low (Fig. 2).
The house of future
An Austrian study showed that the house of tomorrow must meet all following requirements [2-3]:
- the final or primary energy consumption must be low. Table 1 shows the objectives to reach for a low energy house and a passive house. These goals can be reach by:
- a decreasing of the heat losses by transmission (minimization of the exterior walls areas, improvement of the thermal insulation, ...);
- a reduction of heat losses by air conditioning (thermal envelop, re-heating of exterior air, ...);
- an utilization of renewable energies;
- an utilization of high efficient appliances;
- the potable water consumption must be limited to 30 litres per day and per person. This objective can be reached by a used water recycling and the use of raining water;
- the polluting emissions in water, air and ground must be low;
- a high air quality must be reached by a total air replacement at least every three hours. The CO2 concentration must stay under 1000 ppm.
- a high thermal quality can be obtained:
- when the air and the inside surface temperatures are between 18 and 22 °C in winter and between 22 and 25 °C in Summer;
- when the relative air humidity varies between 35 and 70 % and when the absolute air humidity is under 12 g/kg.
- a high visual quality is reached when there are a sufficient day light and a sufficient direct lighting by the sun;
- a high acoustic comfort must be reach with a acoustic level less than 20 dB in life rooms.
Engineers and builders recognize that building high energy efficient housings is a sensible, ethical, ecological idea and workable at medium and long-term. A lot of them think that innovation is an essential component of their job. However, if we observe the
majority of recent or in process buildings, we note easily that the previous considerations are not taken into account at the moment to design or to build the house. Often, we hear the ideas men say "we have a lot of good ideas, but we had not been able to realize them because it was not the good moment or because our clients did not want to apply them or because it is too expensive, too risky."
Table 1
Values to reach for the energy consumption of a low energy house and a passive house compared to an existing house in kW-h/m2 of inhabitable area (Climate corresponding to 3500° day per year)
Consumption Existing house before 1980 Low energy house Passive house
Heating 150-250 < 40 < 15
Final energy < 70 < 42
Primary energy < 160 < 120
To be an innovator it's to know how to put into practice or how to give concrete expression of its creativity. Introduce innovating and environmentally positive solutions is a difficult work. The obstacles are numerous and various: financial obstacles, technical obstacles, psychological obstacles, incompetent professionals or building standards too conservatives [4].
Thermal comfort, healthy inside atmosphere and energy savings
The ventilation is the process allowing to renew the inside air (polluted air) by an outside air (new and clean). Its function is to obtain, in an inside environment, good health, comfort and optimal productivity conditions for the human inhabitant:
1) in giving an air with a sufficient quality for respiration in diluting the polluting substances existing in the inside environment;
2) in controlling the humidity level;
3) in heating or cooling.
However using such a ventilation has a double negative impact: creation of thermal losses and if it is not perfect, it causes a discomfort due to a cold air-stream. From an energy point of view and taking into account the progressive increasing of the thermal insulation of building, the losses due to ventilation accounts for a larger and larger part of the heating needs (up to 30 %). Primary, the various factors exposed before i.e.
- increasing part of the residential sector in the total energy consumption;
- dominating part of the heating in the residential energy consumption;
- heating losses by ventilation being able to reach 30 % of the thermal losses of the building explain the interest to find efficient methods to reduce these losses in increasing the comfort of the occupants. Secondly, the
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