Storyopen EcoNest 26 Passive House Mobile Home — Ultra-Low Energy Edition

The Storyopen EcoNest 26 Passive House Mobile Home is Storyopen’s most thermally ambitious product — a 26-square-metre residential mobile home designed and tested to deliver annual space heating demand below 15 kWh/m²/year, the internationally recognised Passivhaus threshold that makes the building effectively self-heating through a combination of exceptional insulation, airtight construction, solar gain management, and whole-house mechanical ventilation with heat recovery rather than a conventional active heating system. The EcoNest 26 is designed for buyers committed to the lowest possible environmental impact, the smallest possible energy bills, and a residential building that contributes to rather than depletes carbon budgets.

The thermal envelope achieves its Passivhaus-equivalent performance through 200mm vacuum insulation panel (VIP) composite wall construction achieving a U-value of 0.09 W/m²K, a 250mm triple-layer insulated floor cassette with a U-value of 0.08 W/m²K, and a 220mm blown-cellulose roof assembly with a U-value of 0.10 W/m²K. Airtightness is achieved through a continuous vapour control layer sealed at all penetrations and junctions to a tested result of less than 0.6 air changes per hour at 50 Pascal — performance that requires the same discipline of detailing and execution that certified Passivhaus buildings demand. Triple-glazed Passivhaus-certified windows achieve a whole-window U-value of 0.8 W/m²K with frame sections that eliminate all thermal bridges at the glazing perimeter.

Ventilation and indoor air quality are managed by a Zehnder ComfoAir 200 MVHR unit delivering 91%+ heat recovery efficiency, CO2 demand-controlled extract from the kitchen and bathroom, and continuous fresh air supply to the bedroom and living area at flow rates calibrated to BS EN 15251 Category I — the highest indoor air quality category. The 26-square-metre floor plan delivers a double bedroom, open-plan kitchen and living area, and a full bathroom suite. The minimal heating requirement is provided by a single 750W bathroom towel rail as the only active heating source under normal UK winter conditions.

Every Storyopen EcoNest 26 is pressure-tested after construction with a certified blower door test, and the result is provided to the buyer with a full energy performance analysis confirming the predicted annual heating demand based on the tested airtightness figure and the building’s specific orientation.