Energy Efficient Heating and Cooling
Strategies
for Resilient Homes
Compressed Earth Block homes bring unique thermal mass properties that can make your indoor spaces more comfortable, especially when combined with the right energy efficient heating and cooling systems. To get the most out of mass masonry walls, it’s important to understand how they work with your home's heating and cooling setup to boost efficiency and keep your living space cozy year-round.
Energy Efficient Heating and Cooling Options for Thermal Mass Buildings:
Radiant Heating Systems
Radiant heating and cooling systems use pipes in the floors, walls, or ceilings to circulate heated or cooled water. These surfaces then help regulate indoor temperatures, providing consistent comfort and often being more energy-efficient than forced-air systems.
- Hydronic Radiant Systems: These systems circulate heated water through pipes embedded in floors or walls. Hydronic systems are particularly suitable for colder climates, offering energy-efficient heating over large areas.
- Electric Radiant Systems: Electric radiant heating systems use cables or mats installed under the floor surface, making them quick and easy to install, perfect for retrofitting existing spaces. That said, they can be pricier to operate than hydronic systems, especially for larger areas. Because of this, they’re often a go-to choice for smaller spaces or as a way to add extra warmth in specific rooms.
Heat Pumps
A heat pump is a versatile system that provides both heating and cooling by moving heat from one place to another. It works by pulling heat from sources like the air or ground to warm your home, or by doing the reverse to cool it. Since it moves existing heat instead of creating it, it’s an energy-efficient way to keep your home comfortable year-round. Each type of heat pump is suited to different environmental conditions and installation requirements. The choice depends on factors like climate, available space, and installation costs.
- Air-Source Heat Pumps: These are the most common and transfer heat between indoor air and the outside air.
- Ground-Source (Geothermal) Heat Pumps: These systems exchange heat with the ground, utilizing the Earth's stable underground temperatures.
Earth Block Wall Niche with Wood Burning Stove (AI enhanced rendering)Fireplaces and Stoves
- Wood-Burning Fireplaces and Stoves: These traditional heating sources emit high-intensity heat, which earth block walls can absorb and radiate over time. This synergy is beneficial in cold climates, providing warmth even after the fire has subsided.
- Rocket Mass Heaters: Rocket mass heaters are super-efficient wood-burning systems that combine high-temperature combustion with thermal mass storage. They use small amounts of wood, burn it cleanly with very little smoke, and extract as much heat as possible. That heat gets stored in a thermal mass, like a bench or bed made from materials such as cob or compressed earth blocks, which slowly radiates warmth for hours. This setup is perfect for cold climates, offering long-lasting heat while using very little fuel.
- Pellet Stoves: Offering efficient combustion and controlled heat output, pellet stoves are a modern alternative to wood-burning options. They work well with earth block walls, especially in regions where biomass fuel is readily available.
- Gas Fireplaces: While gas fireplaces produce less radiant heat compared to wood-burning options, they offer convenience and can serve as supplementary heating sources in moderate climates.
- Electric Fireplaces: Electric fireplaces offer a convenient and low-maintenance heating option for earth block homes. While they may not provide the same level of radiant heat as wood-burning or pellet stoves, they can effectively supplement heating needs, especially in moderate climates.
Cooling Systems
- Ductless Mini-Split Systems: These systems provide zoned cooling, allowing for targeted temperature control in different areas of the home. In compressed earth block homes, mini-splits can efficiently cool spaces without overburdening the thermal mass, making them suitable for regions with varying temperature ranges.
- Ceiling Fans and Natural Ventilation: Incorporating ceiling fans and designing for natural ventilation can enhance the cooling effects of earth block walls. By promoting air circulation, these methods help dissipate heat absorbed by the walls during the day, especially in areas with cool nighttime temps.
- Geothermal Cooling: Similar to heating, geothermal systems can provide cooling by transferring heat from the home into the ground. Compressed earth walls can store the cooler temperatures, maintaining a comfortable indoor environment during hot seasons.
The Importance of
Energy Recovery Ventilators (ERVs)
Diagram from https://buildingscience.com/sites/default/files/migrate/pdf/BSCInfo_611_Balanced_Ventilation_Systems.pdf
Modern building codes require air-tightness tests for better thermal performance. However, indoor air pollutants, moisture, and odors can get trapped in an air-tight home. That’s where an Energy Recovery Ventilator (ERV) comes in. It works alongside your energy efficient heating and cooling system to improve air quality while keeping your home comfortable.
ERV & Radiant Flooring
- Thermal Efficiency: Radiant floors rely on steady indoor temperatures and minimal heat loss. An ERV helps by continuously ventilating the home without allowing conditioned air to escape, preserving the thermal balance achieved by the radiant system.
- Moisture Control: Radiant flooring is sensitive to humidity levels. The ERV moderates humidity in incoming fresh air, preventing excessive moisture that might affect the comfort of the space.
ERV & Ductless Mini Splits
- Fresh Air Integration: Ductless mini splits are excellent at localized heating and cooling but don't bring in fresh air. An ERV addresses this gap, ensuring the home receives fresh air without needing additional ventilation systems.
- Reduced Load: By pre-conditioning the incoming air (warming it in winter and cooling it in summer), the ERV reduces the workload on mini-splits, improving their efficiency and lifespan.
ERV & Wood-Burning Fireplaces
- Preventing Negative Pressure: Wood-burning fireplaces can create negative pressure in tightly sealed thermal mass homes, leading to drafts or back-drafting. An ERV balances indoor and outdoor pressure by supplying a controlled amount of fresh air, allowing the fireplace to operate efficiently.
- Improved Air Quality: An ERV reduces the buildup of indoor pollutants, such as particulates from wood-burning, by providing continuous ventilation and filtering the air.
ERV & Heat Pumps
- Efficiency Support: Heat pumps are most efficient in tightly sealed homes with controlled ventilation. The ERV maintains this seal while supplying fresh air, reducing the heat pump's workload to condition unventilated or unfiltered air.
- Humidity Balance: Heat pumps can dry out the air during heating. The ERV's ability to manage humidity ensures the air remains comfortable and doesn't strain the heat pump to compensate.
Can I use a conventional central HVAC system, like a standard AC unit and furnace, in a home built with earth block walls?
Can I use a conventional central HVAC system, like a standard AC unit and furnace, in a home built with earth block walls?
Centralized heating and cooling HVAC systems (like furnaces or central air conditioners) use a network of ducts to circulate conditioned air throughout the home. While you can use central AC systems in homes built with compressed earth blocks, they are typically less efficient for buildings with high thermal mass due to the following reasons:
- Rapid Temperature Fluctuations: Forced-air systems heat spaces quickly by circulating warm air. However, thermal mass materials like CEB absorb and release heat slowly. This mismatch can lead to uneven heating, as the walls may not absorb the heat effectively before the system cycles off.
- Short Heating Cycles: The quick heating provided by forced-air systems results in shorter operational cycles. Thermal mass materials require prolonged exposure to heat to absorb and later radiate it back into the space. Short cycles prevent adequate heat absorption, reducing the benefits of thermal mass.
- Air Stratification: Forced-air systems can cause warm air to rise and cool air to settle, leading to temperature variations within the room. This stratification can diminish the uniform temperature distribution that thermal mass aims to provide.
In contrast, radiant heating systems deliver consistent, low-intensity heat over extended periods, aligning well with the thermal properties of mass materials. This synergy enhances energy efficiency and indoor comfort in compressed earth block homes.
How does a geothermal system compare to traditional HVAC systems in terms of cost, efficiency, and long-term maintenance for a residential home?
How does a geothermal system compare to traditional HVAC systems in terms of cost, efficiency, and long-term maintenance for a residential home?
Geothermal systems, or ground-source heat pumps, tap into the Earth’s steady underground temperatures to deliver super-efficient heating and cooling.
- Integration with Hydronic Radiant Systems: Geothermal
systems efficiently supply both heated and chilled water for hydronic
radiant floor heating and cooling.
- Synergy with Ductless Mini-Split Systems:
Geothermal systems pair well with ductless mini-splits for zoned heating and cooling, with the geothermal system managing the main load and mini-splits fine-tuning specific areas.
- Domestic Hot Water Systems: Many geothermal systems include a desuperheater, which captures excess heat to preheat domestic water, reducing the energy required for water heating.
- High Upfront Costs: The cost of installing a residential geothermal system can range from $15,000 to $40,000, significantly higher than conventional HVAC systems. The initial cost savings on utility bills may take 5-15 years to offset the upfront investment, depending on energy prices and system efficiency.
What's the difference between an ERV and an HRV?
What's the difference between an ERV and an HRV?
Heat Recovery Ventilators (HRVs) and Energy Recovery Ventilators (ERVs) are mechanical systems designed to improve indoor air quality by exchanging stale indoor air with fresh outdoor air while conserving energy. The primary difference between the two lies in their handling of humidity:
- HRVs: These systems transfer heat between incoming and outgoing air streams but do not transfer moisture. This makes HRVs suitable for climates with moderate humidity levels, where controlling indoor humidity is less critical.
- ERVs: ERVs also balance indoor humidity by transferring moisture between air streams, keeping excess humidity out in summer and retaining it in winter, especially helpful in humid climates.
Choosing between an HRV and an ERV depends on your local climate and specific indoor air quality needs. In humid climates, an ERV is often more effective at managing indoor moisture levels, while in drier climates, an HRV may suffice.
Climate-Specific Considerations
- Cold Climates: Prioritize heating systems that provide consistent, long-lasting warmth. Radiant heating, hydronic systems, and wood-burning stoves are effective choices. Ensure proper insulation of earth block walls to retain heat and prevent energy loss.
- Hot Climates: Focus on cooling strategies that leverage the thermal mass of earthen walls. Insulation and shading are essential to protect earth block walls from excessive solar gain to prevent overheating.
- Mixed Climates: In regions with both hot and cold seasons, versatile systems like ductless mini-splits and geothermal solutions offer flexibility. These systems can switch between heating and cooling modes, working harmoniously with the thermal mass properties of earth block walls.
Choosing the right energy-efficient heating and cooling systems for compressed earth block homes means understanding how thermal mass works and considering the local climate. By picking systems that work well with the natural properties of earth block walls, you can enjoy better comfort and save on energy. For the best results, consider working with an energy rater and an HVAC designer to create solutions perfectly suited to your home and local climate.
For further information on energy-efficient building practices and thermal mass integration, consider visiting the U.S. Department of Energy's Building Technologies Office and the National Renewable Energy Laboratory.