Sunamp heat batteries in action: a case study of energy-efficient living in New Mexico's LEED platinum home

New Mexico homeowners Kyrie and Hal Stillman designed a one-of-kind, energy-independent residence in New Mexico with LEED Platinum credentials, a globally recognized symbol of sustainability achievement. They named it the RIFT house (Regenerative Ingenuity for Tomorrow) and aim to inspire others to use minimal resources and become net positive in energy.

To maximize renewable energy, they incorporated Sunamp heat batteries for hot water and space heating solutions into their design. Surplus solar energy is used to charge two Sunamp 200 litre equivalent heat batteries; one unit provides hot water for domestic use and the other supplies in-floor heating during the night.

The challenge

The Stillmans understood the need to overcome the challenge of an intermittent power supply. Solar PV systems produce energy when the sun is shining, but not overnight, and in severely reduced amounts in bad weather. Although, excess solar electricity could be stored for use when the sun doesn’t shine in an electric battery system, these are expensive, have a limited lifetime, and are not treated favorably by current utility regulations in New Mexico.

The solution

The RIFT house uses two compact Sunamp thermal batteries to store surplus solar electricity and provide hot water for a timed recirculation system that limits water waste. The heat batteries also supply hot water for supplemental space heating at night in addition to the air-source heat pump system. The space saving heat batteries produce instant hot water when needed, which is circulated through the entire house, providing water at a constant temperature to every fixture.

Also read: Zero carbon hot water for an outdoor kitchen and off-grid home in the US | Solar hot water for an off-grid US home with Sunamp heat batteries

The benefits

As a result of using Sunamp thermal batteries instead of a traditional hot water tank, the RIFT house carbon footprint is reduced by approximately 2,280 kg/year.

Extremely low heat losses, ease of installation, and no maintenance requirement made phase change material (PCM) thermal batteries an ideal solution for this net positive project. As well as providing carbon-free hot water and space heating, the energy-dense Sunamp heat batteries allow for time shifting of renewable energy production to match demand. They are also recyclable and offer long expected usable life – the PCM they use has been proven to last for 50 years continual use with minimal signs of degradation.

The technical details

  • CO2 avoided: approximately 2,280 kg/year
  • Heating source: 2 Uniq 9 connected to solar PV
  • Minimum solar PV production: 19 MWh/year
  • Total electric demand: 12 MWh/year
  • Excess electricity: about 7 MWh/year
  • Storage capacity: 364 x 18kWh (6.56MWh)


Additional information

See RIFT_house on Instagram for details of the construction process:

The RIFT house is designed to maximize the use of environmentally friendly building materials and techniques. The design centres on creating a tight, super-insulated building envelope; achieving net positive energy use; and using materials that are recycled, repurposed waste, or sustainable. The objective of the house is to use a minimum amount of material to create a healthy and stimulating indoor environment and an outdoor environment that helps to regenerate the local ecosystem.

Ready to embrace sustainable living? Contact us to learn how Sunamp heat batteries can power your energy-independent home.