Category Archives: EuroSun2008-5

Use PV to offset non-renewable energy use

Some of the housing renovation projects studied included a PV roof. Decisive is the price at which the local utility is required to buy back the solar electricity. For example in Switzerland as of Jan. 1, 2009 electricity providers must buy back solar power for 25 years for all approved pv installations built since Jan. 1, 2006. For systems <10 kW the buy-back rate for attached PV systems is €0.46 and for systems integrated into the roof or facade €0.56. [9].

An exemplary project where PV was part of a comprehensive renovation is the apartment building in Staufen. The 110 m2 PV installation on the south-facing roof (fig. 1) has a nominal output of 14.7 kWp. In 2006 it fed 14’300 kWh into the grid. The motivation of the owner, Guido Erni, was to provide retirement income. Also part of the renovation were insulation of the attic floor (140 mm), facade (200 mm) and basement ceiling (100 mm); a new ventilation system with 85% heat recovery and replacement of the oil furnace by a heat pump. The results: primary energy use for space and water heating was reduced 65% from 154 to 54 kWh/m2 [10].

Use passive solar design to reduce energy use and improve life quality

Replacing windows with highly insulated units can reduce heat losses to such an extent that solar gains cut heating costs (fig. 8). To minimize unnecessary window opening time and drafts, frame vents can be installed. [11]. Enlarging window openings in walls, when possible, amplifies these savings and admits more daylight. Daylight can also be led into interior spaces by a light pipe [12 + 13].

An example is the renovation of the row houses Kroeven in Roosendaal, the first large — scale passive house renovation project in Holland. Single pane windows were replaced by triple pane glazing in passive house frames.

In addition the walls were insulated with 200 mm XPS and the roof with 360 mm of

cellulose. A new ventilation system was added. A 90% savings in energy consumption resulted, with the annual primary energy for space and water heating being cut from 219 to 21 kWh/m2 [14].

Conclusions

Renovating existing housing can provide living space with superior comfort, very low energy consumption and a special charm. The examples presented here from Austria, Germany, Greece, Italy, the Netherlands and Switzerland demonstrate that it is possible to achieve energy savings up 90 percent, while preserving the special character of the projects. Solar energy is a viable, economic alternative to the costly, last increment of conservation measures in order to achieve the goal of drastically reducing dependency on non-renewable energy and production of CO2. In some of the projects photovoltaic panels were included in the renovation package. When the primary energy value of the solar electricity is deducted from the greatly reduced energy demand for space and water heating, these projects achieve a nearly zero-energy balance.

References

[1] IEA SHC: Renovation Examples, http://www. iea-shc. org/publications/task. aspx? Task=37

[2] Feist, W.: Passivhaus Kriterien, http://www. passivhausprojekte. de/kriterien. php

[3] GAG Ludwigshafen am Rhein Passivhaus im Mietwohnungsbestand: Hoheloogstrafie 1 und 3, WittelsbachstraBe 32, DE-67061 Ludwigshafen, www. gag-lu. de

[4] Calderaro, Valerio: Historic Building in Modena, IT, www. iea-shc. org

[5] Domenig-Meisinger, Ingrid: Passiv House Renovation, Makartstrasse, GIWOG Gemeinnutzige Industrie-Wohnungs-AG Linz http://www. hausderzukunft. at/results. html/id3951

[6] Fehr-Bigger, Hubert, Architekt, Dorfhaldenstrasse 30, CH-8880 Walenstadt Enz, D & Hastings, R.: One-Family House in Walenstadt CH, www. iea-shc. org

[7] Hastings, R. & Morck, O.: Solar Air Systems, Vol. 1 Built Examples, Vol 2 A Design Handbook, Earthscan, London, ISBN 1 873936 85 0 and 1 873936 86 9, www. earthscan. co. uk

[8] Grammer Solar GmbH: Twinsolar, Oskar-von-Miller-Str. 8, DE 92224 Amberg, www. grammer-solar-bau. de

[9] Stickelberger, David: Fakten zur Kostendeckenden Einspeisevergutung KEV fur Solarstrom, Swissolar Infoblat 16.Apr. 2008, www. swissoolar. ch

[10] Enz, D. & Hastings, R.: Apartment Building in Staufen, CH, http://www. iea-shc. org/publications/task. aspx? Task=37

[11] Passivent: Background Ventilation, 2 Brooklands Road, UK-Cheshire M33 3SS, www. passivent. com

[12] Velux: Sun Tunnel Natural Light, VELUX Company Ltd., Woodside Way, UK-Glenrothes Fife KY7 4ND, http://www. velux. co. uk/Products/SUN+TUNNELS/

[13] Glidevale Ltd.: Sunscoop Tublar Roof Lights, 2 Brooklands Road, Cheshire UK-M33 3SS www. glidevale. com

[14] Frank, E. and Bekx, M: Rowhouses, Kroeven in Roosendaal, Holland, Franke Architekten,

Postbus 151, 3360 AD Sliedrecht, Holland, info@frankearchitekten. nl

. Overview of technologies and status for solar heat

J.-C. Hadorn

Groupe Bemey — BASE Consultants SA, Geneva, Switzerland
ichadom@baseconsultants. com

Abstract

This paper presents the state of the art of the main storage solutions for storing solar heat. Keywords: heat storage, seasonal storage, water tank, duct storage, aquifer, solar

1. Storage of heat : overview of classical and advanced materials

Water is a good candidate for all kind of heat storage in the range -30 to 200 C. Table 1 compares basic materials and shows that water has a high volumetric heat capacity.

Thermal

conductivity

@20C

Density

@20C

Volumetric

heat

capacity

@20C

Thermal diffusivity @20C ‘

W/mK

Kg/m3

10+6J/m3

10-8 m2/s

Air

0.025

1.29

0.001

1938

Water

0.6

1000

4.180

14

Ice

2.1

917

2.017

104

Aluminium

237

2700

2.376

9975

Copper

390

8960

3.494

11161

Stainless Steel

16

7900

3.950

405

Concrete

1.28

2200

1.940

66

Marble

3

2700

2.376

126

Glass

0.93

2600

2.184

43

PVC

0.16

1300

1.950

8

PTFE

0.25

2200

2.200

11

Sand (dry)

0.35

1600

1.270

28

Sand (saturated)

2.7

2100

2.640

102

Wood

0.4

780

0.187

214

Cork

0.07

200

0.047

150

Foam glass

0.045

120

0.092

49

Mineral insulation materials

0.04

100

0.090

44

Table 1: Thermal properties of some materials for sensible heat storage

Heat storage candidates

image010

BASE CONSULTANTS

Figure 1: Energy density of some storage material: 3 ranges emerge as competitors to water: PCM, Sorption and Chemical storages.

New solutions have been recently investigated in Task 32 (Figure 1). There is a lot to of potential for medium temperature solutions but as we will see new materials are urgently needed.

Advanced Solar Housing Renovations

image001

Robert Hastings

Donau University

Department of Building & Environment
AT-3500 Krems
robert. hastings@aeu. ch

Abstract

I strongly favour renovating housing because older structures often have a charm and personality lacking in "modern" box architecture. A renovation for me is "advanced" if it fulfils contemporary expectations for appearance, functionality, space and light; and if purchased energy costs are drastically reduced. Often, however, renovations are only superficial. This is tragic because a sensible renovation will not be an issue again for many years. Therefore, clients should be convinced to set high standards for renovations. To achieve ambitious goals, many components and concepts drastically reduce heat losses. However, in existing buildings conservation opportunities are often limited by existing construction or historic preservation. In such circumstances, producing energy is an economical alternative to extreme conservation. The obvious means is harnessing the sun, be it by photovoltaics, solar thermal or passive solar design. When a renovation includes a sensible mix of conservation and solar measures, and drastically improves living quality, it can truly be said to be an "advanced solar housing renovation". Examples of comprehensive renovations and their performance from across middle Europe are presented here, based on documentation completed in a Subtask of IEA-SHC 37.

Keywords: housing, renovation, solar, international

Подпись:1. Introduction

Successful, innovative renovation projects are a good source of ideas, can convince a client to set ambitious goals and are helpful in setting realistic targets. Exemplary renovations from seven countries have been documented in an IEA-SHC project [1]. The combined strategies of conservation and solar use achieve up to 90 percent reduction in non-renewable energy demand. Primary energy use for space and water heating was reduced to between 40 and 70 kWh/m2a. The renovation strategies not only save energy, they also improved living quality, comfort and functionality, as well as increasing real estate values. As in new building design, careful detailing is the key to beauty, effectiveness and durability in renovation projects (fig. 1).

Storage using the building structure

To collect solar heat in a building windows are effective! In order to avoid high temperature swing, thermal mass must be however present inside the protected volume, i. e. inside the insulated envelope. Internal thermal mass can be used from 19 to 24C, barely more. Depth of penetration is however limited and all the thickness of a wall or slab cannot be used during a daily cycle. For concrete it has been shown that only the first 10 to 14 cm can be really used for a diurnal storage. In our example the necessary wall area becomes then 70 m2, free of carpets, paintings, furniture, wood or other thermal and radiation barriers. Any measure that can improve thermal mass in a building favours the comfort.

PCM in walls

To improve storage, several solutions of PCM (phase change materilal), embedded or not, into construction elements have been invented and tested since more than 30 years. Today 2 types of PCM

solutions for storing into of close to the structure of a building might see a future on the market: cool ceilings and PCM in microencapsulated balls inside a wall element.

PCM in microencapsulated polymers are now on the market. They can be added to plaster, gypsum or concrete to enhance the thermal capacity of a room, at a pre-defined temperature (22 or 24C). For renovation they provide a good alternative to new heavy walls.

Rock beds

Storage of air heated by a solar air system can be achieved in rock beds. The blocks of rock are between 1 to 10 cm diameter. Air is blown through the bed at low speed to heat up the rocks. Several solar houses have been built on this principle and works to satisfaction. It is not seasonal storage, and needs a air collecting and distributing system. Water solutions for storage are preferred because water collectors are more efficient than air collectors, and water can transfer much higher power rates than air.