Material Ecology Assignment 3: Perfect House Student: Alexander Weiss, Dominic L端ftenegger SS 2014
Content 1. MAIN CRITERIA 2. BUILDING SHAPE | CONSTRUCTIVE SUSTAINABILITY 2.1 Criteria for material selection and construction 2.2 Choice of the insulation material: 3. Construction Materials | Elements 3.1 Load bearing structure 3.2 Interior materials 3.3 Facade 3.4 Windows 3.5 Shading components 3.5 construction materials 4. HEATING and energy 4.1 Heating energy distribution 4.2 Heating system and insulation 4.3 Photovoltaic system 4.4 Domestic Hot water
Dominic L端ftenegger Alexander Weiss
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1. MAIN CRITERIA A) Recyclabilty | Reusability B) Embodied Energy C) Durability and maintenance D) Comfort
2. BUILDING SHAPE | CONSTRUCTIVE SUSTAINABILITY Our aim with this building is to reach the highest possible durability. Therefore we propose a multi-generation family- and low energy demand building which should be flexible enough to fulfill the demands of many generations. Therefore we split the building volume in 3 independent, though combineable residential units and designed a grid (which can be seen on the facade) which allows a very high flexibility and adaptability. Also the facade can easily be adapted to the chnaging owner´s demands. In the beginning we thought about surrounding baclonies to enable the occupants to go outside and which should contribute to a very long life span of the facade. But because of the additional shading and especially because we have realized that the facade can last for the lifespan of about one or two generations and the next occupants may be willing to change the building´s appearance, we decided to keep the balconies away and to save the materials needed to build the balconies (which would also need maintenance). The building is located in Bregenz, Austria close to the lake of constance. The facade with the main part of glass is facing towards south to optimize the solar gains during winter and to have highest possible amount of daylight to prevent a vast use of artificial light.
Dominic Lüftenegger Alexander Weiss
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u-wert.net
Alle Angaben ohne Gewähr
Außenwand, W/m²K 2.1Außenwand Criteria forSchafwolle: material selection and U=0,105 construction
(erstellt am 5.5.2014 13:18)
The materials should be recyclable in largest possible construction should offer thighest possible comfort to U = 0,105 Kein TA-Dämpfung: 625.0 part, though they mustW/m²K be long-lasting. Longevity andTauwasser the user in terms of humidity, surface and air tempera(Wärmedämmung) (Feuchteschutz) maintainance are crucial factors in terms of sustainature, acoustics but also visually (Hitzeschutz) (brightness, reflection bility. Lowest possible embodied energy is obligatory. etc.). The materials as single components and combined as * 0
EnEV Bestand : U<0,24 W/m²K0.5
0 Tauwasser (kg) Kein Tauwasser
1
Temperaturamplitudendämpfung: 625.0 Phasenverschiebung: 19.2h
Raumluft: 20°C / 50%
Tauwasser: 0.00 kg/m²
Gewicht: 257 kg/m²
Außenluft: -10°C / 80%
sd-Wert: 11.8 m
Dicke: 58.92 cm
2.2 Choice of the insulation material:
Temperaturverlauf / Tauwasserzone Exterior wall constructionTemperaturverlauf
Temperatur Taupunkt
20
Temperatur [°C]
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-10 0
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600 [mm]
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Claytec Lehm-Oberputz fein (3 mm) Claytec Lehm-Unterputz (20 mm) Leichtlehmstein NF 1200 (115 mm) pro clima Intello Plus (0,2 mm) klimalan plus (260 mm) Lärche (20 mm) Schilf- / Strohplatte (100 mm) Claytec Lehm-Unterputz (20 mm) Hinterlüftung (30 mm) Vorhangfassade (21 mm)
Außen
Alle Angaben ohne Gewähr Verlauf von Temperatur und Taupunkt innerhalb des Bauteils. Der Taupunkt kennzeichnet die Temperatur, bei der Wasserdampf kondensieren und Tauwasser entstehen würde. Solange die Temperatur der Konstruktion an jeder Stelle über Außenwand Schafwolle: Außenwand, U=0,105 W/m²K (erstellt am 5.5.2014 13:18) der Taupunkttemperatur liegt, entsteht kein Tauwasser. Falls sich die beiden Kurven berühren, fällt an den Berührungspunkten Exterior wall aus. Sheepwool Tauwasser
U = 0,105 W/m²K (Wärmedämmung)
Kein Tauwasser
Schichten (von innen nach außen)
(Feuchteschutz)
TA-Dämpfung: 625.0 (Hitzeschutz)
0Folgende EnEV Bestand U<0,24die W/m²K 0.5 0 Daten aller Tauwasser 1 Temperaturamplitudendämpfung: 625.0 Tabelle*:enthält wichtigsten Schichten(kg) der Konstruktion: Kein Tauwasser Phasenverschiebung: 19.2h
#
Raumluft:Material 20°C / 50%
λ Tauwasser: 0.00 kg/m²
R Temperatur [°C]kg/m² Gewicht Tauwasser Gewicht: 257 [m²K/W] min maxcm [kg/m²] [Gew%] Dicke: 58.92 Wärmeübergangswiderstand 0,130 19,6 20,0 Alle Angaben ohne Gewähr 1 0,3 cm Claytec Lehm-Oberputz fein 0,820 0,004 19,6 19,6 5,1 0,0 2 2 cm Claytec Lehm-Unterputz (Grundputz) 0,820 0,024 19,5 19,6 34,0 0,0 Temperaturverlauf / Tauwasserzone Außenwand Neptutherm: Außenwand, U=0,121 W/m²K am 5.5.2014 3 11,5 cm Leichtlehmstein NF 1200 0,470 0,245 18,7 (erstellt 19,5 138,013:17) 0,0 4 0,02 pro climaTemperaturverlauf Intello Plus 0,170 0,001 18,7 18,7 0,1 0,0 Exterior wallcm Neptutherm 5 20 26 cm klimalan plus 0,037 Temperatur 7,027 -3,4 18,7 9,1 0,0 W/m²K Kein Tauwasser 6 U =20,121 cm Lärche 0,130 Taupunkt 0,154TA-Dämpfung: -3,9 -3,4 1250.0 9,2 0,0 1 7 15 (Wärmedämmung) 10 cm Schilf- / Strohplatte 0,056 1,786 -9,5 -3,9 19,0 0,0 (Feuchteschutz) (Hitzeschutz) 2 3 4 5 6 7 8 8 2 cm Claytec Lehm-Unterputz (Grundputz) 9 0,820 0,024 -9,6 -9,5 34,0 0,0 1 Claytec 0,130 Lehm-Oberputz fein (3 mm) 10 Wärmeübergangswiderstand -10,0 -9,6 10 * 2 Claytec Lehm-Unterputz 09 EnEV Bestand : U<0,24 W/m²K 0.5 0 Tauwasser (kg) 1 Temperaturamplitudendämpfung: 1250.0 3 cm Hinterlüftung (Außenluft) -10,0(20 mm) -10,0 0,0 Kein Tauwasser Phasenverschiebung: 23.3h 3 Leichtlehmstein NF 1200 10 5 2,1 cm Vorhangfassade -10,0(115 mm) -10,0 9,4 4 pro clima9,524 Intello Plus (0,2 mm) 268 kg/m² 258,0 Tauwasser: 0.00 kg/m² Gewicht: Raumluft: 20°C / 50% 58,92 cm Gesamtes Bauteil 0 Außenluft: -10°C / 80% sd-Wert: 11.8 m5 klimalan plus (260 mm) Dicke: 58.92 cm 6 Lärche (20 mm) -5 7 Schilf- / Strohplatte (100 mm) 8 Claytec Lehm-Unterputz (20 mm) Temperaturverlauf / Tauwasserzone -10 9 Hinterlüftung (30 mm) Temperaturverlauf Seite 1/4 10 Vorhangfassade (21 mm) *Vergleich mit dem Höchstwert gemäß EnEV 2014 für erstmaligen Einbau, Ersatz oder Erneuerung von Außenwänden 0 100 200 300 400 500 600 Temperatur 20 3, Tabelle 1, Zeile 1).. (Anlage [mm] Innen www.u-wert.net Außen Taupunkt Dominic Lüftenegger 1 4 Hier klicken, um das Bauteil auf www.u-wert.net zu bearbeiten. 15 Alexander Weissbei der 3 4 5 6 7 des 8 Bauteils. Der Taupunkt kennzeichnet die Verlauf von2 Temperatur und Taupunkt innerhalb Temperatur, 9 Wasserdampf kondensieren und Tauwasser entstehen würde. Solange die Temperatur der Konstruktion 1 Claytec Lehm-Oberputz fein (3 mm)an jeder Stelle über 10 10
u-wert.net
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Temperatur [°C]
Außenluft: -10°C / 80%
[W/mK] sd-Wert: 11.8 m
Material straw bales cellulose Sheep wool reed Hemp boards EPS wood fiberboard -
Λ (W/mK) 0,052 0,039 0,040 0,056 0,040 0,036 0,045
Primary energy (kWh/m³) 41,4 * 839,5 947,2 1206,4 2390,4 6480 13064,4
Density (kg/m³)
Chem. treated
100 55 30 85 50 18 160
N Y Y N Y N
Source: www.unserstrohhaus.at/co2-bilanz-strohbau
Cellulose: In terms of grey energy and insulation features, cellulose is the most efficient, followed by straw and - grey energy per m² insulation in exterior wall (24cm): 725,33 MJ = 201,5 kWh then reed. A disadvantage of cellulose is that chemicals are needed to protect it from insects and to - thermal resistance of 24cm cellulose: 6,66 m²K/W fireproof but with this treatment becomes a quite long-lasting material. Reed and straw - make itU-value of total construction = 0,152itW/m²K are yes not treated with chemicals what makes them more ecologic and recyclable but to - constructions Chemicals: make them fire and insect proof, a layer of clay plaster which must be air proof is needed. Since no air gets to the reed or straw, it is fire proof for more than 90 minutes (relating to the film about straw Reed: bale constructions “Stroh im Kopf – ein alter Baustoff wiederentdeckt” ) but the clay plaster layer on - grey energy per m² exterior wall (26cm): 1129,18 MJ = 313,66kWh and cold side (the exterior onem²K/W must also be protected with a curtain wall) makes it all in all - the warm thermal resistance cellulose: 4,64 - quite costly. U-value of total construction = 0,15 W/mK - Chemicals: no
Comparison: Straw bale: - grey energy per m² exterior wall (30cm): 38,77 MJ = 10,77kWh - Cellulose: thermal resistance cellulose: 5 m²K/W - U-value of total construction = 0,13 W/mK - Chemicals: grey energy - no per m² insulation in exterior wall (24cm): 725,33 MJ = 201,5 kWh - not really approved in terms longevity and it requires a quite costly constriction to - Disadvantage: thermal resistance of 24cm cellulose: 6,66ofm²K/W pro tect the straw from insects and moisture - U-value of total construction = 0,152 W/m²K -
Chemicals: yes
We tried a few variants of exterior wall constructions den neuen Baustoff, organisiert Netzwerktreffen und Reed: and with many we had problems with vapor and hu- gnz wichtig: kümmert sich um die erforderlichen Tests midity. took out the most interesting für MJ die =baustoffliche - We grey energy per three m² exterior wall (26cm):(and 1129,18 313,66kWh Zulassung. Im Juli 2003 z.B. hat applied an “ecologic” vapor barrier as further variants. der Baustoff Strohballen den Brandschutztest “F90” - thermal resistance cellulose: 4,64 m²K/W In terms of grey energy and insulation (all construc- geschafft! Wir waren mit der Kamera dabei, als eine - U-value of total construction = 0,15 W/mK tions have the same thickness of insulation), cellu- Strohballenwand, auf beiden Seiten mit Lehm verno followed by straw and then putzt, mit 1000 Grad Celsius befeuert wurde und lose is- theChemicals: most efficient, reed. The problem with cellulose is that chemicals are der Hitze 90 Minuten lang allen Kriterien standhielt.“ Straw bale: needed to protect it from insects and to make it fire- source: Crystal Lake Video). proof. Reed and straw constructions do not need any - grey energy m² exterior wall (30cm): 38,77 MJ = 10,77kWh chemicals what makesper them more ecologic and recy- They thermal resistance cellulose: clable. get the fire protection by 5a m²K/W layer of clay Conclusion: plaster mustofbe air proof. Since no=air gets to the The very low primary energy demand and the fact of - which U-value total construction 0,13 W/mK reed -or straw, it is fire proof for more than 90 minutes not needing any chemical substances made us deciChemicals: no (relating to the film about straw bale constructions de for straw bales. The well insulation characteristics “Stroh im Kopf – ein alter Baustoff wiederentdeckt” are also a benefit and of course for a “life cycle buil-„ Der “Fachverband Strohballenbau” informiert über ding” it is good to use 100% recyclable materials.
Dominic Lüftenegger Alexander Weiss
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3. Construction Materials | Elements | Energy 3.1 Load bearing structure All vertical bearing elements like columns and walls are made out of wood. Due to this local material a long durability as well as a high sustainability is given. The exact construction you can see in the detailed facade section. For the ceiling as well as the flat roof a hybrid of wood
and concrete construction is used. The combination of these two materials allows to take the advantages of each relating to its thickness and span width.
3.2 Interior materials The interior should provide a very pleasing and homey environment and also a comfortable climate. Clay stones and clay plaster on the interior of the walls function as regulation of the humidity, as thermal mass and for a comfortable room climate radiating the gained heat energy slowly back to the room. It also contributes to a better sound insulation from outside since the exterior walls are light construction.
Wooden floors combined with floor heating should create a feeling of a warm and pleasing environment, the walls and ceiling painted white reflect the incoming daylight and make the room bright, giving it the comfort of plenty of daylight. A mechanical ventilation system with heat recovery providing the fresh air and maintaining a hygienic climate.
3.3 Facade On the facade one can clearly read the flexible structure of the interior by the continuing dominant lines and the spaces in between are covered split in smaller, finer parts. All the facade is a curtain wall and it is made of wood. The direction of the wood fibers is vertical since this is contributinto the durability of the wood because if it rains against the facade the vertical direction of the fibers lead the water faster and easily downwards off the wood´s surface preventing the fouling of the wood. There also several studies which
proved that wood which is croped at a certain state of the moon is more insect-, weather- and UV-resistant. Therefore we propose the use of „moon wood“. Another benefit of a wooden curtain wall is that it can easily removed, recycled and replaced by either new wood or other materials. This fact and the flexible shape and arrangement of the facade makesthe building very adaptable even for further generations which can then adapt the buil-
3.4 Windows To gain an optimal sustainable project, the building has several big windows facing south and some small windows facing north. To avoid overheating, a aluminum shading system is assembled (see also chapter „shading“). To reach a very long durability the
windows in our project consist of hybrid woodenaluminum frames. Due to this construction the wooden elements of the windows are protected by rain. A triple-glazing causes a great heating insulation.
3.5 Shading components The shading system is made out of aluminum, which has the big advantage of its long durability. Due to this movable shading system (jalousie) which closes automatically at a solar irradiation of 100W/m2 in summer it is not necessary to cool the building down.
Dominic Lüftenegger Alexander Weiss
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3.5 construction materials
timber columns straw or reed
straw bale
clay stones
clay plaster
Straw bale construction without vapor barrier - condensate occurs; U-value: 0.13W/m2K
clay plaster
100
100100
Straw bale construction with vapor barrier - no condensate; U-value: 0.13W/m2K
exterior wall part at timber column with 10cm straw or reed; U-value: 0.194W/m2K
25 25
3 3 5 2 3 11 2 2 112 11
40 40
40
1m2 of exterior wall consits of 17cm column and 83cm straw bale part. 0,194*0,17 + 0,13*0,87 = 0,146W/m2K Dominic L端ftenegger Alexander Weiss
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4. HEATING and energy 4.1 Heating energy distribution The heating energy will be gained with a heatpump which will be powered by photovoltaic cells. The heat will be distributed in the building through heating floors. In this building we would use a floor heating system with individual heat control for each room to adapt the room temperature individually to provide ma-
ximum comfort for the occupants. The interior should provide a very pleasing and homey environment and also a comfortable climate. The clay stones and clay plaster on the interior of the walls are radiating the gained heat energy slowly back to the room. Wooden floors create a warm and pleasing environment.
4.2 Heating system and insulation Insulation: Cellulose Heating system: Wood pellets Cellulose [cm]
U-value [W/m2K]
Q [MJ/m2a]
EEh Wood Pellets [MJ/a]
EEh lifetime (50 years) [MJ/a]
EEm [MJ]
Difference [MJ*50a]
6000,00
10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160
0,32 0,18 0,12 0,09 0,08 0,06 0,06 0,05 0,04 0,04 0,04 0,03 0,03 0,03 0,03 0,03
265,42 148,47 102,02 77,97 66,36 53,08 45,62 41,47 35,67 33,18 29,86 27,37 24,88 23,22 21,57 20,74
95,55 53,45 36,73 28,07 23,89 19,11 16,42 14,93 12,84 11,94 10,75 9,85 8,96 8,36 7,76 7,46
4777,57 2672,46 1836,38 1403,41 1194,39 955,51 821,15 746,50 641,99 597,20 537,48 492,69 447,90 418,04 388,18 373,25
46,86 93,72 140,58 187,44 234,3 281,16 328,02 374,88 421,74 468,6 515,46 562,32 609,18 656,04 702,9 749,76
4730,71 2578,74 1695,80 1215,97 960,09 674,35 493,13 371,62 220,25 128,60 22,02 -69,63 -161,28 -238,00 -314,72 -376,51
5000,00
4000,00
3000,00
2000,00
limit of Cellulose = 117,5cm
1000,00
0,00
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20
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50
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EE wood pellets (50 years)
Insulation: Cellulose Heating system: Heat-pump Cellulose [cm]
U-value [W/m2K]
Q [MJ/m2a]
EEh Heat Pump (non renewable) [MJ/a]
10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160
0,32 0,18 0,12 0,09 0,08 0,06 0,06 0,05 0,04 0,04 0,04 0,03 0,03 0,03 0,03 0,03
265,42 148,47 102,02 77,97 66,36 53,08 45,62 41,47 35,67 33,18 29,86 27,37 24,88 23,22 21,57 20,74
185,79 103,93 71,41 54,58 46,45 37,16 31,93 29,03 24,97 23,22 20,90 19,16 17,42 16,26 15,10 14,52
EEh lifetime (50 years) [MJ/a]
EEm [MJ]
Difference [MJ*50a]
9289,73 5196,44 3570,74 2728,86 2322,43 1857,95 1596,67 1451,52 1248,31 1161,22 1045,09 958,00 870,91 812,85 754,79 725,76
46,86 93,72 140,58 187,44 234,3 281,16 328,02 374,88 421,74 468,6 515,46 562,32 609,18 656,04 702,9 749,76
9242,87 5102,72 3430,16 2541,42 2088,13 1576,79 1268,65 1076,64 826,57 692,62 529,63 395,68 261,73 156,81 51,89 -24,00
120
130
140
150
160
EE Cellulose
straw bale [cm]
U-value [W/m2K]
Q [MJ/m2a]
EEh Wood Pellets
EEh lifetime (50 years)
EEm [MJ]
Difference [MJ*50a]
10 20 30 40 50 60 70 80 90 100 110 120 130 140 150
0,40 0,23 0,16 10000,00 0,12 0,10 9000,00 0,08 8000,00 0,07 7000,00 0,06 0,06 6000,00 0,05 5000,00 0,05 0,04 4000,00 0,04 3000,00 0,04 2000,00 0,03
331,78 188,28 131,05 100,36 81,29 68,84 58,89 52,25 46,45 42,30 38,15 34,84 32,35 29,86 28,20
119,44 67,78 47,18 36,13 29,26 24,78 21,20 18,81 16,72 15,23 13,74 12,54 11,65 10,75 10,15
5971,97 3389,09 2358,93 1806,52 1463,13 1239,18 1060,02 940,58 836,08 761,43 686,78 627,06 582,27 537,48 507,62
9,555 19,11 28,665 38,22 47,775 57,33 66,885 76,44 85,995 95,55 105,105 114,66 124,215 133,77 143,325
5962,41 3369,98 2330,26 1768,30 1415,36 1181,85 993,14 864,14 750,08 665,88 581,67 512,40 458,05 403,71 364,29
1000,00 0,00
limit of Cellulose = 157cm
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EE Heatpump (50 years)
Insulation: Straw bale Heating system: Wood pellets
120
130
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EE Cellulose
Insulation: Straw bale Heating system: Heat-pump
straw bale [cm]
U-value [W/m2K]
Q [MJ/m2a]
EEh Wood Pellets
EEh lifetime (50 years)
EEm [MJ]
Difference [MJ*50a]
straw bale [cm]
U-value [W/m2K]
10 20 30 40 50 60 70 80 90 100 110 120 130 140 150
0,40 0,23 0,16 0,12 0,10 0,08 0,07 0,06 0,06 0,05 0,05 0,04 0,04 0,04 0,03
331,78 188,28 131,05 100,36 81,29 68,84 58,89 52,25 46,45 42,30 38,15 34,84 32,35 29,86 28,20
119,44 67,78 47,18 36,13 29,26 24,78 21,20 18,81 16,72 15,23 13,74 12,54 11,65 10,75 10,15
5971,97 3389,09 2358,93 1806,52 1463,13 1239,18 1060,02 940,58 836,08 761,43 686,78 627,06 582,27 537,48 507,62
9,555 19,11 28,665 38,22 47,775 57,33 66,885 76,44 85,995 95,55 105,105 114,66 124,215 133,77 143,325
5962,41 3369,98 2330,26 1768,30 1415,36 1181,85 993,14 864,14 750,08 665,88 581,67 512,40 458,05 403,71 364,29
10 20 30 40 50 60 70 80 90 100 110 120 130 140 150
0,40 0,23 0,16 0,12 0,10 0,08 0,07 0,06 0,06 0,05 0,05 0,04 0,04 0,04 0,03
Q EEh Heat 6000,00 [MJ/m2a] Pump (non 331,78 188,28 131,05 100,36 81,29 68,84 58,89 52,25 46,45 42,30 38,15 34,84 32,35 29,86 28,20
EEh lifetime (50 years)
EEm [MJ]
Difference [MJ*50a]
11612,16 6589,90 4586,80 3512,68 2844,98 2409,52 2061,16 1828,92 1625,70 1480,55 1335,40 1219,28 1132,19 1045,09 987,03
9,555 19,11 28,665 38,22 47,775 57,33 66,885 76,44 85,995 95,55 105,105 114,66 124,215 133,77 143,325
11602,61 6570,79 4558,14 3474,46 2797,20 2352,19 1994,27 1752,48 1539,71 1385,00 1230,29 1104,62 1007,97 911,32 843,71
232,24 131,80 91,74 70,25 4000,00 56,90 48,19 41,22 3000,00 36,58 32,51 29,61 2000,00 26,71 24,39 22,64 1000,00 20,90 19,74 5000,00
0,00 10
20
30
40
50
60
70
80
90
100
Dominic L端fteneggerEE wood pellets (50 years) 8 Alexander Weiss
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EE C
4.3 Photovoltaic system An area of about 8m² of PV has a performance of about 1kWp. 52m² of PV system would be needed to provide enough renewable energy to run the heat pump for heating, domestic hot water and the ventilation system.
We came to the conclusion that it would be the most efficient and sustainabe system if we combine a heat pump (COP of about 4.5) with a Photovoltaic system to provide the electrical energy that is needed to run the heat pump. Since a PV system is energetically amortised after a few years (5 - 7) it would be very energy saving combined with the heat pump with a COP value of 4.5 what means that the heat pump gains 4.5 times the energy in form of heat that was put in. As we compared the maximum insulation thickness in terms of ecological efficency we saw that it would be more sustainable to use 157cm of cellulose if the builing was heated with a heat pump powered by non renewable energy (gas, oil,...) what would be th case if it was just plugged in at the regular electricity net. So the PV system would be very efficient and it delivers also electricity when no heat is needed (during spring and summer).
- it delivers additional electric energy during summer when it is not needed for the heat pump and it has still a purpose when the solar radiation is the strongest. The electricity can be stored in form of heat (electric boiler) and other, for households not very common methods but there is another model of “storing” it. The electricity can also be fed in the local electricity network. The owner of the PV system gets some money from the local electricity provider and can buy it back for almost the same price (just a bit more).
We decided for a polycrystalline PV system which has an efficiency nearly as good as the monocrystalline one´s but it needs much less energy to be produced.
- it works with light, not with thermal solar radiation and it has some gains even with diffuse light on cloudy days.
Further advantages of a Photovoltaic system:
4.4 Domestic Hot water To provide the domestic water we would use a domestic hot water heat pump which would also be powered by the PV system. The COP value of 4.5 will have a very good impact on the energy demand. The average demand of heated water per person and day is about
40 liters. WIth water saving technologies and water saving quench heads in the showers it should be reduced to about 30 liters since the most warm water is needed for washing /showering.
Dominic Lüftenegger Alexander Weiss
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