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EWI and Passive Solar Design

Passive solar design refers to a set of architectural and building principles. These principles harness the sun’s energy to provide heating, cooling, and lighting for structures without relying on mechanical or electrical devices. This approach capitalises on the natural movement of heat and light. This incorporates elements such as building orientation, thermal mass, insulation, and ventilation. Ultimately, it aims to create energy-efficient, comfortable, and sustainable living spaces.

Components of Passive Solar Design

The essential components of passive solar design include:

  1. Building orientation – The placement and orientation of a building play a crucial role in maximising solar gain. In the Northern Hemisphere, structures should ideally face true south to absorb maximum sunlight during winter months. This also minimises direct sun exposure during the summer months.
  2. Glazing – Windows, skylights, and other transparent materials are crucial in passive solar design, as they facilitate the entry of sunlight into the building. These elements should be strategically placed to optimise solar gain during winter and minimise it during summer. Typically, south-facing windows are favoured, while east and west-facing windows are limited, and north-facing windows are minimised.
  3. Thermal mass – Materials with high thermal mass, such as concrete, brick, or stone, store heat during the day and release it slowly at night. This stabilises indoor temperatures. These materials are typically incorporated into walls, floors, and ceilings to absorb and redistribute the sun’s energy.
  4. Insulation – Effective insulation is crucial in passive solar design. It helps retain heat during the winter and prevents it from entering during the summer. Insulation materials, such as cellulose, fibreglass, or foam, are used in walls, roofs, and floors. As a result, heat loss is minimised.
  5. Ventilation – Natural ventilation strategies, such as operable windows, vents, and strategically placed openings, help maintain comfortable temperatures by allowing cool air to enter and warm air to exit the building. Passive cooling techniques, such as shading devices and roof overhangs, also contribute to controlling solar gain and promoting natural air circulation.
  6. Daylighting – Passive solar design considers the optimal use of natural light to minimise the need for artificial lighting. This includes proper window placement, light shelves, and reflective surfaces to distribute daylight evenly throughout the interior space.

By integrating these components, passive solar design offers a sustainable, energy-efficient, and cost-effective solution for modern buildings. It not only reduces the reliance on fossil fuels but also contributes to a healthier and more comfortable living environment for occupants.

Insulation focus

Insulation is a critical component of passive solar design. It helps maintain comfortable indoor temperatures by reducing heat transfer between the building’s interior and exterior. Proper insulation significantly contributes to energy efficiency. It does so by minimising heat loss during the winter and preventing heat gain during the summer. The effectiveness of insulation is determined by its thermal resistance. The thermal resistance or R-value indicates the material’s ability to resist heat flow.

There are various types of insulation materials, each with its unique characteristics, benefits, and applications:

  1. Fibreglass – Fiberglass insulation is made from fine strands of glass fibres, which are woven together. They form a lightweight, non-flammable, and moisture-resistant material. This type of insulation is available in batts or rolls, as well as loose-fill.
  2. Cellulose – Manufactured from recycled paper products, cellulose insulation is an eco-friendly option with excellent thermal and sound insulation properties. It can be blown into cavities, walls, and attics, or installed as dense-pack insulation in new construction.
  3. Mineral wool – Comprising rock wool or slag wool, mineral wool insulation is made from molten minerals spun into a fibrous material. It is highly resistant to heat, fire, and sound, making it suitable for walls, floors, and ceilings. Mineral wool is available in batts, rolls, and loose-fill forms.
  4. Expanded polystyrene (EPS) and extruded polystyrene (XPS) – EPS and XPS are rigid foam insulation materials that provide excellent thermal resistance and moisture protection. They are lightweight, easy to install, and can be used in walls, roofs, and foundation systems.
  5. Polyurethane and polyisocyanurate – These closed-cell foam insulation materials offer superior R-values and excellent moisture resistance. They can be applied as spray foam or rigid foam boards, making them suitable for walls, roofs, and other building elements.
  6. Reflective insulation – Reflective insulation consists of a reflective foil layer, typically aluminium, bonded to a substrate such as paper, plastic film, or foam. It reduces heat transfer by reflecting radiant heat away from the building. As such it is particularly useful in hot climates or for reducing heat gain in attics and roofs.

In passive solar design, insulation is strategically placed throughout the building envelope, including walls, roofs, and floors, to minimise heat transfer. Additionally, special attention is paid to sealing gaps and air leaks around windows, doors, electrical outlets, and other penetrations to prevent drafts and further improve energy efficiency.

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