How to Integrate an HVAC System with ICF Construction
Insulated concrete form (ICF) construction creates superior homes that are incredibly energy-efficient. Because ICF homes are so much more efficient and built more airtight than traditional homes, integrating with the home’s HVAC system has to be approached differently. Knowing what to look for and working with a professional who has built with ICF before will ensure you’ll be comfortable in your home all year round.
What Are Insulated Concrete Forms?
Insulated concrete form blocks are made from two sheets of expanded polystyrene foam insulation secured together with a proprietary tie system. The panels create a cavity between them resulting in a 16" by 48" block that can easily be stacked and interlocked together to form a wall.
On a construction site, these blocks are assembled into the walls of the home being built. Once stacked, rebar is placed into the cavity. Concrete is then poured into the blocks to lock the wall together. Once the concrete has cured, what is left is a steel reinforced concrete structure with both an inner and outer layer of continuous insulation.
ICF homes are known for many things including being incredibly durable and exceptionally energy-efficient. An ICF home’s insulation, thermal mass, and airtight levels lead to a home that can use energy much more efficiently than traditional homes. ICF homes when evaluated by Energy Raters easily score HERS rating well below the National average and achieve top Energy Star ratings.
Having two layers of continuous insulation, an inner and outer layer, make ICF construction much more energy-efficient than traditional wood framed construction. It is simply much harder for heat to move through the walls of an ICF home.
In addition to having much more insulation than a traditional home, the continuous ICF home insulation prevents thermal bridging from occurring. Thermal bridging happens when a path is formed in an insulated wall that gives heat the ability to easily move through the wall. In traditional wood-framed construction, the cavity between studs is filled with insulation, but the studs themselves and any fasteners end up acting as thermal bridges. This phenomenon results in the entire wall being less energy-efficient. ICF homes naturally avoid thermal bridging.
Lack of Air Leaks
A wood framed home’s exterior walls have many components including exterior cladding, a vapor barrier, air barrier, insulation, studs, plates, and drywall. Each of these layers is typically added in different stages and presents many opportunities for installation mistakes to occur. These mistakes, along with natural settling over time, result in a wall that allows some air to move in and out of the building.
ICF homes are different because the walls themselves are thicker and filled with liquid concrete. The concrete prevents any possible routes from forming that could allow air to leak into or out of the home. This means your home won’t lose precious cool air in the summer and warm air in the winter.
Concrete is heavy. The thick walls of an ICF home are no exception. All of that mass not only leads to homes that can be used as storm shelters, but also helps dampen temperature swings outside from affecting the temperature inside.
The thermal mass concrete walls of an ICF home naturally retain heat. After warming all day long, the concrete will continue to keep your home warm even as night falls and the temperature drops. As the concrete cools overnight, the opposite process occurs helping to cool the home throughout the day. The opposite is true for high heat areas, the mass concrete moderates the temperature change through the wall assembly resulting in less work by the HVAC system to either heat or cool the home.
What Equipment Does an ICF Home Need?
The energy-efficient nature of an ICF home means that the HVAC system will typically be smaller than for a comparably sized, traditionally built home. Selecting high efficiency equipment is the best way to maximize both energy efficiency and comfort in your new home.
Heat pumps are similar to air conditioners but are able to run in reverse as well. This means your air conditioner can also double as an energy-efficient heater in the winter. A properly sized heat pump is a great way to keep your home at a comfortable temperature year round.
Having come down in price significantly over the last few years, mini splits are a perfect way to provide additional heating or cooling to rooms that need it. Mini splits are typically mounted on the wall and resemble the A/C units from hotel rooms. They are used to control the temperature in a single room in an energy-efficient way.
To get the benefit of a mini split with a traditional heat pump or forced air system, consider adding in a zoned system with programmable thermostats. When a traditional air conditioner or furnace runs, warm or cool air is pushed throughout the home regardless of the temperature in each room. A zoned system works by using multiple thermostats throughout the home to measure temperature in different rooms. Dampers in the ductwork are used to allow or block the airflow to different rooms based on the thermostat readings.
For example, the dining room and living room may need cooling but the bedroom is at a comfortable temperature. The damper for the bedroom would close allowing cool air to flow to the dining room and living room but not into the bedroom. Zoned systems help keep the entire home at a comfortable temperature no matter the time of year or how the home is being used.
The benefits of thermal mass in the walls can be extended to the floors too. Radiant underfloor heating systems are installed underneath a wood, tile, or stone flooring system. The radiant heater warms the floor and concrete slab which then radiates heat to the room.
Just like in mini split or zoned systems, each room can be controlled independently. Radiant floor heating systems heat differently, making people feel as though they are wrapped in a blanket of warmth even if the air temperature is a bit lower. With radiant floor heating systems, the thermostat can be turned to a lower temperature which further increases energy efficiency.
While the lack of air leaks in an ICF home is a good thing, it is still important to get fresh air into a home. Traditional construction actually assumes that homes are leaky enough to avoid needing to make sure fresh air gets in.
ICF homes are very air tight and require conditioned air to be circulated through to home . An energy recovery ventilator is a must for these high-performance homes. Conditioned air from bathrooms and other parts of the home is pulled through a heat exchanger and exhausted out of the home. Fresh air is pulled in from outside and passed through the other side of the heat exchanger. An energy recovery ventilator makes it possible to keep the energy in the home while throwing away stale air and bringing in fresh air.
Use Fox Blocks for Your ICF Home
When building a new home, use materials that you know will last. Fox Blocks ICF homes are resilient, low-maintenance, and energy-efficient. When paired with the proper HVAC system, your home will be safe and comfortable all year round no matter what nature throws at it.
To learn more about why your home should be made of Fox Blocks ICF, reach out to our team today.