Passive Solar ICF Home Plans: Costs and Design Best-Practices

Passive Solar ICF Home Plans

Passive solar insulated concrete form (ICF) home plans strive to minimize a home's energy consumption while ensuring a high level of comfort to the family.

Effective passive solar strategies lessen cooling and heating loads through window orientation, high thermal mass materials, like Fox Blocks insulated concrete forms (ICFs), ventilation, and shading strategies. Year-round, passive solar houses maintain a constant-comfortable temperature while minimizing energy use, reducing energy bills by 65 percent compared to typical building methods.

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The Cost of a 1,600 ft2 Passive ICF Solar House

Building an ICF passive solar house ranges between $100 and $155 per square foot, depending on the complexity of the design and level of finishing of the home. It will cost between $160,000 and $248,000 to build a 1,600 ft2 passive solar house.

Will ICF Cost More than Wood Construction?

Before the extreme increase in lumber costs and construction labor shortages, ICF construction added about 3 to 5 percent to the price of a wood-frame home, amounting to $5,280 to $8,800 for a $176,000 new home.

However, this figure no longer applies due to the extreme increases in lumber. As a result, you will pay $18,600 more for an average new single-family wood-framed home and nearly $7,300 for a multifamily home over April 2020 prices.

Cost to Build a Zero-Energy Home

The design of a net-zero-energy house must also include active solar systems, like wind systems, solar photovoltaic (PV) panels, small "hybrid" electric systems, or microhydropower. These systems use electrical and mechanical components to capture and convert the energy found in wind, sunlight, and moving water for use in the home.

Installing solar panels in a 1500 ft2 house with a 6kW solar panel system will cost about $18,500. It will take between seven and twenty years to recoup your investment. Solar panels can increase your home's value by 4.1 percent, or an additional $9,274 for the median-valued home in the U.S.

Building passive solar houses that achieve net-zero-energy status costs about 10 percent more than code-compliant, less energy-efficient homes. Building a net-zero-energy, passive solar 1,600 ft2 home with ICF will cost between $176,000 and $272,800.

Note that all cost estimates are just estimates; please inquire for current pricing.

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Design of Effective Passive Solar ICF Home Plans

Passive solar design includes several vital components: south-facing home and windows, thermal mass materials, ventilation, and shading strategies. The design of a high-performing energy-efficient home must also include a tight building envelope (walls, glazings, roof, and foundation) that protects against air and moisture infiltration.

Home and Window Orientation in Passive Solar Design

Passive solar plans work with nature rather than against it, to control solar gains through house orientation and window placement. Therefore, the home must have an unobstructed view of the Sun.

  • In the Northern Hemisphere, facing the long side of your home south will maximize sunlight during the winter (lessening heating demands) and minimize direct sunlight during the summer (lowering cooling demands). The windows can also alleviate the need for artificial light by allowing natural light to bathe the house during the day to save more energy.

  • The south side of the house should feature glass to receive sunlight throughout the day, best for the most occupied spaces, like kitchens and living rooms.

  • Limit north-facing windows to avoid heat loss due to a lack of direct sunlight.

  • Limit windows facing east and west since they gain a lot of heat, and require shades, awnings, etc., to keep the spaces cool.

High Thermal Mass Materials

Once the Sun’s energy enters a home, it absorbs into high thermal mass products, like brick, tile, stone, and ICFs. Heat energy stored in these materials will stabilize tem­per­a­ture shifts within the house, to limit energy use and create a comfortable indoor environment.

For instance, thermal mass absorbs and stores cold air in the evening during warm months. During hotter days, the thermal mass materials stay cool, to keep the home's interior cool.

Ventilation (Distribution)

Passive solar house design requires fans, ducts, and blowers to circulate collected solar heat from the storage points (thermal mass) to the different areas of the house.

However, air-tight ICFs (with CI) can trap pollutants, like volatile organic compounds, radon, and formaldehyde. Therefore, passive solar ICF house design must include ventilation, like an energy recovery ventilation system to remove the toxins. An energy recovery ventilation system also lessens energy loss by moving energy from conditioned air outside, to allow fresh air inside.

Shading Strategies

Passive solar ICF home plans include:

  • Placing overhangs or awnings over the windows

  • Shading in the summer

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Fox Blocks - a Superior Wall System for Passive Solar ICF Home Plans

Fox Blocks ICFs offer superior thermal mass, effectively absorbing the Sun’s energy and significantly contributing towards a comfortable, passive solar home. Fox Blocks provide CI and moisture-resistance, vital features of a high-performing, energy-efficient home.

  • Fox Blocks CI (R-value of 23), exceeds ASHRAE/ANSI 90.1 energy code requirements, to produce homes that need 32 percent less energy to cool and 44 percent less energy to heat than a wood-framed house.

  • Fox Blocks ICF creates a solid continuous monolithic concrete wall system with a perm rating below 1.0, to control moisture infiltration and prevent the growth of structurally damaging and unhealthy mold. Therefore, for above-grade walls, Fox Blocks do not require a WRB.

  • A Fox Blocks building envelope enables a Net Zero Ready home and with the addition of other passive design elements and solar panels, will be able to achieve Net Zero energy.

Use ICF for Your Next Passive Solar Home Plan

The thermal mass of ICF wall systems directly absorbs the Sun’s energy during the day from all of the home's angles, and releases significantly more heat during the cool evenings than other interior thermal mass materials, tremendously lessening cooling and heating loads on the house.

Don't hesitate to contact Fox Blocks ICF experts today to learn more about utilizing ICFs for your passive solar build.