Curved SIP Custom Home, Montana

Project Overview

This unique residence serves as the informal office for the owner's Alternative Energy Resource Institute and a residence for participating visitors and relatives. It features a distinctive curved design using Structural Insulated Panels (SIPs), with three bedrooms, a full kitchen, and a bath. The home is situated to support both the educational goals of the institute and provide comfortable lodging.

Design and Sustainability

The home is architecturally striking with its vaulted, half-cylindrical shape, achieved through the use of curved 12" SIPs forming a 20' radius vault. This innovative use of SIPs not only ensures superior insulation and airtightness but also contributes to the building's rapid enclosure due to the modular nature of the panels.

Why SIPs?

SIPs were integral in achieving the desired insulation values and minimizing air infiltration, which would have been challenging with traditional construction methods such as curved glulams or a metal Quonset structure. The choice of SIPs facilitated a design that is both energy-efficient and structurally robust without the need for internal horizontal rods due to the rigidity provided by interior buttresses made from 6-1/2" SIPs.

Innovative Design and Engineering Elements

• Structural Rigidity: Interior buttresses constructed from SIPs enhance the structural integrity of the vault.
• Exterior and Interior Finishes: The exterior features an additional layer of SIPs OSB to unify the panel sections, while the interior employs a triple layer of OSB at panel interfaces, adding both strength and a unique architectural element.
• Flooring and Interior Walls: Commercial vinyl tile is used for flooring, and all interior walls are covered with OSB instead of traditional drywall.

Heating and Ventilation System

• Heating System: The building utilizes a highly efficient wood-fired gasification boiler integrated into a closed-loop radiant floor heating system, with no additional backup heating.
• Ventilation: A ducted balanced Heat Recovery Ventilation (HRV) system ensures optimal air quality and energy efficiency.

Energy Efficiency and Off-Grid Capability

• Windows: High-performance Serious Windows 525 series with low SHGC glass reduce heat gain.
• Off-Grid Power: The structure is completely off-grid, equipped with a 4KW PV system and three 1KW wind generators.
• Insulation: The rim and mudsill were spray-foamed to match the wall/roof R-value, enhancing the building’s overall energy efficiency.

Sustainable Materials and Design Features

• Recycled Materials: The building incorporates sustainable materials such as recycled content in decking materials and 26 gauge colored standing seam steel for roofing.
• Resource Reuse: The new structure replaces and reuses the basement of a removed triple-wide, maintaining the same off-grid power system.

Additional Features and Innovations

• Blower Door Tests: Conducted throughout construction to identify and mitigate air infiltration, achieving an exceptionally low infiltration rate.
• Interior Design: Bamboo butcher block countertops and low VOC paint are used within the interiors, reflecting the building’s commitment to sustainability.

Key Features

This home at the Alternative Energy Resource Institute exemplifies cutting-edge sustainable design, integrating advanced energy-efficient technologies and materials with innovative architectural and structural solutions. It serves as a model for environmentally conscious living and a practical demonstration of the institute’s core values in alternative energy education and conservation.