Designing for the Earth: A Global Guide to Earth Sheltered Homes

Earth sheltered homes, also known as underground houses or earth bermed homes, represent a unique and increasingly relevant approach to sustainable architecture. These structures utilize the earth as thermal mass, offering significant energy savings, protection from extreme weather, and a reduced environmental footprint. This guide explores the principles, benefits, design considerations, and diverse architectural styles of earth sheltered homes around the globe.

What is Earth Sheltered Architecture?

Earth sheltered architecture is the practice of designing and building structures that are partially or completely buried in the earth. This design approach leverages the earth's stable temperature and insulating properties to create a comfortable and energy-efficient living environment. The specific design and construction techniques vary depending on the local climate, soil conditions, and available resources, resulting in a diverse range of earth sheltered homes worldwide.

Benefits of Earth Sheltered Homes

Earth sheltered homes offer a multitude of benefits compared to conventional above-ground construction:

Energy Efficiency

The earth acts as a natural insulator, maintaining a relatively constant temperature year-round. This reduces the need for heating in winter and cooling in summer, resulting in significant energy savings. Studies have shown that earth sheltered homes can reduce energy consumption by 50-80% compared to traditional homes.

Example: In temperate climates like parts of Northern Europe or the Pacific Northwest of the United States, an earth-sheltered home requires dramatically less heating during the winter months. The earth’s thermal mass buffers the interior temperature, reducing reliance on fossil fuels or electricity for heating.

Protection from Extreme Weather

Earth sheltered homes are highly resistant to extreme weather events such as hurricanes, tornadoes, earthquakes, and wildfires. The earth provides a protective barrier against strong winds, flying debris, and intense heat, making these homes a safe haven in disaster-prone areas.

Example: In regions prone to hurricanes, like the Caribbean or the Southeastern United States, earth-sheltered homes offer enhanced structural stability and protection against wind damage and flooding compared to conventional construction.

Noise Reduction

The earth acts as a natural sound barrier, significantly reducing noise pollution from external sources. This creates a peaceful and quiet living environment, particularly beneficial in urban areas or near busy roads.

Example: Near airports or industrial zones, earth-sheltered homes can substantially minimize noise intrusion, creating a more tranquil living space for occupants.

Reduced Maintenance

Earth sheltered homes typically require less maintenance than conventional homes. The earth protects the exterior walls from weathering and damage, reducing the need for painting, siding repairs, and other upkeep tasks.

Example: In harsh climates with significant temperature fluctuations, the reduced exposure to the elements translates into lower maintenance costs and a longer lifespan for the building materials.

Environmental Benefits

Earth sheltered homes have a reduced environmental footprint compared to conventional homes. They require less energy for heating and cooling, reduce reliance on non-renewable resources, and minimize disruption to the surrounding landscape. The use of sustainable building materials, such as rammed earth or recycled materials, further enhances their environmental benefits.

Example: An earth-sheltered home built with locally sourced materials and incorporating passive solar design principles demonstrates a commitment to sustainable living and reduces the overall environmental impact of the building.

Privacy

Earth sheltered homes offer increased privacy due to their partially or fully buried structure. This can be particularly appealing in densely populated areas or for individuals seeking a secluded living environment.

Aesthetic Appeal

While often associated with a specific architectural style, earth sheltered homes can be designed to be aesthetically pleasing and blend seamlessly into the surrounding landscape. Many earth sheltered homes feature green roofs, which further enhance their visual appeal and provide additional insulation.

Types of Earth Sheltered Designs

There are several different types of earth sheltered designs, each with its own advantages and disadvantages:

Bermed Homes

Bermed homes are the most common type of earth sheltered design. They are built into a hillside or slope, with earth banked against one or more exterior walls. The roof is typically exposed, but it can also be covered with earth to provide additional insulation.

Advantages: Relatively easy to construct, good natural lighting and ventilation, can be adapted to a variety of site conditions.

Disadvantages: Requires a suitable hillside or slope, potential for moisture problems if not properly waterproofed.

Example: Many earth-bermed homes can be found in regions with rolling hills, such as parts of the Midwestern United States or Southern England.

In-Hill Homes

In-hill homes are built directly into a hillside, with the entire structure buried except for the entrance. The roof and walls are completely covered with earth.

Advantages: Excellent insulation, maximum protection from the elements, good privacy.

Disadvantages: Can be difficult and expensive to construct, limited natural lighting and ventilation, requires careful waterproofing.

Example: The Hobbiton movie set in New Zealand, while fictional, provides a visually appealing example of in-hill dwellings.

Underground Homes

Underground homes are completely buried below ground level, with the roof and walls covered with earth. They are typically accessed through a staircase or ramp.

Advantages: Maximum insulation and protection, excellent privacy, minimal visual impact on the landscape.

Disadvantages: Difficult and expensive to construct, requires extensive excavation, limited natural lighting and ventilation, requires careful waterproofing and drainage.

Example: Some underground homes are built in arid climates to take advantage of the earth's cooling properties, such as in parts of the Southwestern United States or the Middle East.

Chamber Homes

Chamber homes are constructed above ground and then covered with earth. They can be built using a variety of materials, such as concrete, steel, or wood.

Advantages: Easier to construct than in-hill or underground homes, good flexibility in design, can be adapted to a variety of site conditions.

Disadvantages: Can be more expensive than bermed homes, requires careful waterproofing and drainage.

Example: Chamber homes can be a good option for flat sites where a hillside is not available.

Design Considerations for Earth Sheltered Homes

Designing an earth sheltered home requires careful consideration of several factors:

Soil Conditions

The type of soil is a critical factor in the design and construction of earth sheltered homes. The soil must be stable, well-draining, and free of contaminants. A geotechnical investigation is essential to determine the soil's load-bearing capacity, permeability, and chemical composition.

Example: Clay soils can be problematic due to their poor drainage and tendency to expand and contract with changes in moisture content. Sandy or gravelly soils are generally preferred for their good drainage properties.

Waterproofing

Waterproofing is essential to prevent moisture from penetrating the structure and causing damage. A comprehensive waterproofing system should include a waterproof membrane, drainage layer, and proper grading to direct water away from the building.

Example: Bentonite clay is a common waterproofing material used in earth sheltered construction. It expands when wet, creating a watertight seal.

Structural Integrity

The structure must be strong enough to withstand the weight of the earth and any additional loads, such as snow or vegetation. Reinforced concrete is a common building material for earth sheltered homes due to its strength and durability. Alternative materials like rammed earth or earthbags require specialized design and construction techniques.

Example: Properly engineered reinforced concrete walls and roof are essential for supporting the earth load and ensuring the structural integrity of the building.

Ventilation

Proper ventilation is essential to maintain indoor air quality and prevent moisture buildup. Natural ventilation can be achieved through the use of strategically placed windows and vents. Mechanical ventilation systems may also be necessary, especially in completely underground homes.

Example: A passive ventilation system that utilizes the stack effect to draw fresh air into the home and exhaust stale air can significantly improve indoor air quality.

Lighting

Natural lighting can be challenging to achieve in earth sheltered homes, especially in completely underground structures. Skylights, light wells, and strategically placed windows can help to maximize natural light penetration. Artificial lighting should be energy-efficient and provide adequate illumination.

Example: Light tubes, also known as tubular daylight devices, can effectively bring natural light into interior spaces without compromising the building's insulation.

Accessibility

Accessibility is an important consideration, especially for individuals with mobility limitations. Ramps, elevators, and wide doorways may be necessary to ensure that the home is accessible to all occupants.

Example: Designing the entrance with a gradual slope instead of stairs can make the home more accessible for wheelchair users.

Local Building Codes and Regulations

It is important to comply with all local building codes and regulations. Some jurisdictions may have specific requirements for earth sheltered construction, such as setbacks, drainage, and structural design.

Sustainable Building Materials for Earth Sheltered Homes

The choice of building materials is crucial for the sustainability of earth sheltered homes. Sustainable materials minimize the environmental impact of the construction process and contribute to a healthier indoor environment.

Rammed Earth

Rammed earth is a natural building material made from compacted soil, gravel, and clay. It is durable, fire-resistant, and has excellent thermal mass properties. Rammed earth walls can be load-bearing, eliminating the need for a separate structural frame.

Example: Rammed earth construction is commonly used in arid climates due to its ability to regulate indoor temperature and humidity.

Earthbags

Earthbags are made from polypropylene or burlap bags filled with soil. They are stacked and tamped to create walls. Earthbag construction is a low-cost and sustainable building method that is suitable for a variety of climates.

Example: Earthbag homes are often used in disaster-prone areas due to their affordability, ease of construction, and resistance to earthquakes and floods.

Recycled Materials

Recycled materials, such as recycled concrete, recycled steel, and recycled plastic, can be used in earth sheltered construction to reduce waste and conserve resources.

Example: Recycled concrete can be used as a foundation material or as aggregate in concrete walls.

Wood

Wood can be used for framing, roofing, and interior finishes. Sustainable forestry practices should be followed to ensure that the wood is harvested responsibly.

Example: Using sustainably harvested timber from certified forests helps to minimize the environmental impact of wood construction.

Global Examples of Earth Sheltered Homes

Earth sheltered homes can be found in a variety of climates and cultures around the world. Here are a few notable examples:

The Hobbit House, Wales

This eco-friendly home was built by a family in Wales using sustainable materials and traditional building techniques. It is partially buried in the earth and features a green roof, blending seamlessly into the surrounding landscape.

Malator, Wales

Also known as the Teletubby House, Malator is a unique earth sheltered home located in Pembrokeshire, Wales. The structure is built into a hillside and features a single window overlooking the sea.

Cave Dwellings of Cappadocia, Turkey

For centuries, people in Cappadocia, Turkey have lived in cave dwellings carved into the soft volcanic rock. These homes provide natural insulation and protection from the elements.

The Underground City of Coober Pedy, Australia

Coober Pedy, Australia is an opal mining town where many residents live in underground homes to escape the extreme heat. These homes are known as "dugouts" and provide a comfortable and energy-efficient living environment.

Earthships, United States

Earthships are off-grid homes built from recycled materials, such as tires, bottles, and cans. They are designed to be self-sufficient, with systems for water harvesting, solar power, and waste management. They are predominantly found in the Southwestern United States but are gaining popularity worldwide.

The Future of Earth Sheltered Architecture

As concerns about climate change and sustainability continue to grow, earth sheltered architecture is poised to become an increasingly important building trend. With advancements in building technology and a growing awareness of the benefits of sustainable living, earth sheltered homes are becoming more accessible and affordable. By embracing the principles of earth sheltered design, we can create more resilient, energy-efficient, and environmentally friendly homes for the future.

Conclusion

Earth sheltered homes offer a unique and compelling solution to the challenges of sustainable living. By harnessing the earth's natural insulating properties and utilizing sustainable building materials, these homes can significantly reduce energy consumption, protect against extreme weather, and minimize their environmental impact. As we look towards a more sustainable future, earth sheltered architecture has the potential to play a significant role in creating a more resilient and environmentally responsible built environment. Further research and development in this field are crucial to making earth-sheltered living a more accessible and widespread option globally.