Passive Solar Systems

The northern facade incorporates three passive solar systems:

1 The sunspace, a large glazed volume, is thermally coupled to the house by four complimentary heat flow mechanisms: forced convection to a rock bed beneath the living area, natural convection to the living areas through openable windows, radiation through the closed windows, and transmission through mass walls.

2 Direct solar gains are obtained through openings with favourable orientations for winter sun. These windows are in the kitchen, dining-living room and ground floor bedrooms, as well as on the upper floor.

3 Mass storage walls consists of two dense wall panels with exterior glazing placed on the north facade, with summer shade provided by a roof overhang.

4 Two Trombe walls are also placed on the north facade with a combined exposed surface area of 5.5 m2.

Rockbed system

A rockbed system was built following the recommendations and sizing methods given by Balcomb. It consists of two, 12 m3 rockbeds with two channels each. Each channel is 6 m long and 0.8 m deep. The rocks used have an average diameter of 150 mm. The solar gains from the upper part of the greenhouse are transferred to the rockbed beneath the living area of the house using ducts with thermostatically controlled fans. After heating the rocks the air returns to the sunspace. The whole system was designed to store 21 kWh day-1 with a storage capacity of 1.5 days. The fans provide an airflow rate of 0.7 m3 s-1. The system is thermally coupled through the slab, acting as an underfloor heating system.

The large glazed sunspace is a key feature of the house and fulfils a series of thermal and functional objectives:

• in addition to the solar gains on sunny days, the volume acts as a thermal buffer, reducing heat losses from the house on cold cloudy and windy days;

• this intermediate buffer area can be used for family activities when the weather is unfavourable, as it is protected from rain, snow, wind and low temperatures. During sunny spells in winter the temperature increase in the sunspace will be favourable;

Solar Sunspace Greenhouse

in the rocks to rooms above t0 the greenhouse

Passive solar systems.

in the rocks to rooms above t0 the greenhouse

Passive solar systems.

Rock Bed Passive Heating

Rockbed, by Manuel Fuentes.

Rockbed, by Manuel Fuentes.

• the exposure of the sunspace to summer sun may produce overheating owing to the intensity of solar radiation. Five measures were therefore adopted to control this problem:

• upper floor balcony: provides shade, especially to windows between the sunspace and ground floor. The roof overhang serves a similar purpose on the upper floor;

• high-level opening windows: designed to allow the exit of hot air to the exterior while allowing ingress of cooler air at a lower level. The stack effect to achieve this is reinforced by the double height;

• thermal insulation and double-glazed windows: reduce the thermal transmission to indoor spaces in summer.

Domestic solar hot water (DSHW) system

The house has a flat plate solar collector manufactured by AES and mounted on the roof co-planar with the photovoltaic panels. The solar hot water collectors are used to supplement the energy demand for domestic hot water (DHW). The 5 m2 collector is considered to be cost-effective for a single family in Bariloche. The solar hot water collector was predicted to supply 76 per cent of the household requirements. The domestic hot water system was designed for the highest solar fraction. For this purpose, the roof was tilted 35°. The collector feeds directly into a pre-heated or 'solar' tank (250 l) that feeds into the primary tank, which is a conventional 150-l tank heated by a high-efficiency, Peisa-manufac-tured gas boiler. The principle for choosing this two-tank, preheated system was to have the best technology available in Argentina that could be quickly adapted to produce a high solar fraction system with a gas boiler back-up.

Was this article helpful?

0 0
Getting Started With Solar

Getting Started With Solar

Do we really want the one thing that gives us its resources unconditionally to suffer even more than it is suffering now? Nature, is a part of our being from the earliest human days. We respect Nature and it gives us its bounty, but in the recent past greedy money hungry corporations have made us all so destructive, so wasteful.

Get My Free Ebook


Post a comment