Appropriate Designs was formed in 1983 by John Siegenthaler to provide engineering design services specifically focused on low-energy-use buildings. Specialties include solar energy applications, super-insulated construction, and hydronic heating.

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In the years that followed, Appropriate Designs developed construction plans and energy systems for dozens of homes and light commercial buildings. Many used advanced energy systems including solar heating, geothermal heat pumps, and off-peak thermal energy storage. Many of these systems where based on the use of hydronic heating technology.

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During the 1990s, Appropriate Designs began offering customized training seminars on hydronic heating, specializing in radiant panel heating. Since then, hundreds of seminars and workshops have been presented across the US and Canada.

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Today the company focuses solely on state-of-the-art application of hydronic heating. Through extensive research and application of engineering principles, Appropriate Designs has developed advanced modeling methods for simulating the thermal and hydraulic performance of hydronic systems. These models have been used to develop software-based sizing and selection programs for several manufacturers, as well as numerous publications, and training seminars.