Living off-the-grid in an extreme climate presents unique challenges for managing temperatures efficiently without access to modern amenities. But, with careful planning and strategic use of passive heating, cooling, natural building materials, and insulation, it is possible to create a comfortable shelter able to withstand temperature extremes. This article outlines key techniques for thermal regulation under such conditions.
Passive Solar Heating
Passive solar heating harnesses the sun’s energy to warm shelters during cold weather. It requires proper solar orientation and incorporation of thermal mass – materials that absorb, store, and distribute heat.
Direct Solar Gain
The most straightforward approach is direct solar gain through south-facing windows. Sunlight enters the windows and directly heats the interior space. Thermal mass materials like masonry floors or walls then absorb and slowly release the heat. Avoid placing insulation between the thermal mass and windows, as this prevents absorption of the solar energy.
Indirect Solar Gain
An isolated solar gain system uses a separate sunspace to capture solar radiation. The thermal mass material is located in the sunspace itself. Vents and fans then circulate air from the sunspace into the living space. This keeps the main interior out of direct sunlight while still harnessing solar heat from the separate sunspace.
Earth Sheltering
Partially underground or bermed buildings leverage the natural stable temperatures of the surrounding earth for heating or cooling. Face the above-ground portion toward the winter sun and use high solar heat gain windows along with thermal mass materials for solar heat storage. The earth insulation will retain this warmth captured during the day.
Passive Cooling Techniques
Several passive approaches can cool shelters during hot weather without electricity:
Solar Shading
Properly sized roof overhangs, awnings, shade trees and shrubbery can substantially reduce solar heat gain by shading the building. Optimize window placement and sizing to facilitate cross ventilation while minimizing unwanted heat entry.
Natural Ventilation
Strategically placed windows, doors, and vents allow cooler exterior air to enter the interior space, while venting out hot interior air. This air exchange is enhanced when coupled with proper solar shading.
Earth Coupling
As with earth sheltering, earth coupling uses the natural stable subsurface temperatures for cooling. Below grade walls and floors will feel cool to the touch, providing passive cooling to the space.
Evaporative Cooling
Water evaporation provides natural cooling through convection and works best in dry climates. Techniques like roof pond systems, water walls, and misting devices take advantage of this effect.
Thermal Mass and Night Purging
High heat capacity thermal mass materials can provide a “heat sink” during hot days. Store coolness in these materials at night by opening windows to vent out warm interior air. Close windows during the day so stored coolness in the thermal mass passively moderates interior temps.
Natural and Sustainable Building Materials
Choosing appropriate building materials improves insulation and thermal regulation. Locally available renewable materials have lower environmental impact while providing better moisture control:
Stone, Earth and Adobe – Offer high thermal mass to reduce temperature swings. Being dense materials, they also block heat transfer well.
Wood – Has low embodied energy and naturally insulating properties. Best sourced locally.
Straw Bales – Provide thickness for insulation and thermal mass in one material. They are also easy to source and assemble.
Cob – This composite of clay, sand, straw and earth creates thick earthen walls with thermal mass as well as insulation value.
Insulation Techniques
Properly insulating the building envelope is crucial for maintaining stable interior temperatures. Focus insulation efforts based on climate:
Cool and Temperate Climates
Insulate thoroughly to retain captured solar heat from the passive design during cold seasons. Attention to reducing air infiltration and exfiltration is key.
Hot and Humid Climates
Insulate mainly to keep heat out during warm seasons. Place insulation on the exterior side of underground shelters to block heat absorption from the surrounding earth.
All Climates
- Achieve recommended R-values for your climate zone’s temperatures.
- Use natural insulation materials like wool, cellulose, straw bales wherever possible.
- Eliminate thermal bridging from structural elements piercing insulation.
Banking Snow for Additional Insulation
One free and readily available material that can provide insulation value is snow. Shoveling or piling snow against exterior walls creates an extra layer of insulation to help regulate interior temperatures.
How It Works
- Banking 2-4 feet of snow against outside walls adds insulation through the many air pockets inherently found in snow.
- Just 1 inch of snow can add 1 or more R-value of insulation.
- A 2-4 foot snow bank can perform similarly to having a 6 inch thick layer of fiberglass batt insulation (R-18) on the wall.
- This approach is beneficial for any shelter but especially older structures with less built-in wall insulation.
- Snow banks should be maintained after snowfalls throughout the winter if possible to maintain consistent coverage.
Considerations
- Snow banking is most effective with consistent snow cover and minimal thawing/melting cycles.
- Piled snow touching wood walls increases chances of insect intrusion.
- Does not negate the need for proper insulation elsewhere like attics.
- Ventilated roofs help reduce diminished insulation from snow loads.
With some maintenance of the snow banks, this free approach can provide supplementary insulation and assist in regulating interior shelter temperatures. It works best as part of an overall insulation strategy. Monitoring for insect issues is prudent if banking snow directly against wood structure.
Following passive solar design principles and thoughtfully incorporating natural building techniques tailored to the climate will facilitate thermal regulation in off-grid shelters. Monitoring temperatures and adjusting these approaches during each season will further enhance performance. With some refinement, shelter occupants can successfully maintain safe and steady interior temperatures throughout the year.
