Category EuroSun2008-5

Strategy insulate the exterior

For non-historic buildings, exterior insulation is the standard solution, but to insulate to the PH Standard is advanced. The apartment building, Hoheloogstrasse in Ludwigshaven, is an example of an extreme renovation (figure 2). Wall, roof and the basement ceilings received 20, 24 and 12 cm of insulation. Windows were replaced with PH-quality units, thermal breaks were eliminating and mechanical ventilation with heat recovery added. As a result, the annual heating energy demand was reduced from 250 to 15 kWh/m2. After stripping the building to its structure, it was possible to integrate heat recovery ventilation and construct modern, spacious apartments. Finally, PV was integrated into the entire south-facing roof [3].

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Seasonal storage requires large volumes

Seasonal storage is of course possible with sorption and even more with chemical storage (see figure 1). But there is no solution yet mainly due to very little research in the field. Since 30 years seasonal storage has been investigated to reach high solar fractions, up to 100% solar, the final dream.

How big should a tank be to reach 100% solar? Many studies and experience have been conducted to solve this question. There are a few examples that actually are in operation! In the 80s it was calculated that a seasonal water storage should be as big as half the house, limitating its interest. That was indeed true but what happened is the stong demand reduction for heating a house. Savings of energy prior to investing for a new production device!

For a recent passive house, the volume is much...

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Strategy insulate the room-side of the walls

This villa in Modena is under historic preservation (figure 3). The solution was to build a masonry wall on the room side of the existing wall. The cavity between it and the old wall is insulated with coconut and cork panels, 40 and 60 mm thick, reducing the U-value from 1.75 to 0.25 W/m2K.

New insulating glass windows were installed on the room side of the old windows to preserve the character of the facade. Primary energy demand for space and water heating is reduced 81% from 367 to 70 kWh/m2. The old 104 kW boiler could be replaced by a 35 kW condensing gas boiler. 12 m2 of vacuum tube collectors on the south faqade

of the interior court space help cover this reduced energy demand [4] Fig. 3: Historic villa in Modena IT renovated with

interior insulation (V. Calderaro)

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Strategy Solar Insulation (GAP)

The heating costs of a 50 unit apartment building built in 1957 Linz AT were reduced by 88 %. The comprehensive renovation included an innovative solar insulation system of prefabricated panels (figure 4). Sunlight passes through a glass layer and is trapped in the air gaps of corrugated cardboard (with a fire suppressant). The resulting warm air buffer reduces heat losses by the facade. The static U-value is 0.15 but the dynamic U-value over the heating season approaches zero. To reduce thermal bridges, the balconies were glazed and at the same time enlarged. Conventional insulation was added to the roof and the ground floor (U = 0.16 and 0.20 W/m2K). New windows were installed (Uw =

0.86 W/m2K) with louvered blinds within the glazing unit for sun shading...

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Use Solar Heat to reduce non-renewable energy use

Подпись: Fig. 5: Collector may not be installed on farm house, must be on the rear shed, requiring the nut tree to be cut down. (Photo: AEU Ltd.) 3.1. Goal, benefits and problems

If the goal is to reduce dependency on non­renewable energy, at a certain point energy delivered from a solar thermal system becomes less expensive than energy saved from conservation measures, i. e. the marginal cost of the last increment of insulation or triple verses double glazing. Installing solar collectors or a pv system as part of a renovation is not always easy, however. Panels may be forbidden because they disturb the character of an historic village. Figure 5 shows the outline of the proposed and refused location for roof solar panels. The building commission allowed that the panels could be mounted on the shed to the rear, which, however is shaded by an old, noble nut tree.

Well done renovations drastically shorten the

heating season...

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Strategy: Solar water systems

Three years after a young Swiss couple purchased a single-family house built in 1942 the oil furnace had to be replaced. This was the motivation to completely renovate the house, including a 13 m2 drain-back solar system (fig. 6) with an 800 L storage tank.

The renovation also included adding roof, wall and basement ceiling insulation (220,

200 and 80 mm). The windows were replaced with units glazed with a Ug of 0.55. The oil burner was replaced with a wood pellet stove and a ventilation system with 80% heat recovery was added. As a result, the solar system is able to cover much of the space heating in spring and fall and all the domestic water heating demand in summer...

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Strategy: Solar air systems

Solar heat from a collector can be transported by air, instead of water. No anti-freeze is needed and a possible leak causes no damage.

Over the years this technology has been used in the renovation of many houses, schools and industrial buildings [7]. An example of a very practical application, solar heating second homes, is given here.

Often after a stone rustico or wooden chalet in the Alps, log cabin in Scandinavia or masonry cottage in the Mediterranean has been purchased, it must be renovated. While vacant it becomes cold, damp and mouldy. When the owners arrive, the air and bedding smell musty and it likely takes forever to bring the mean radiant room temperature up to a comfort level...

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