Rundbalshuset, Umeå

Thermotech has delivered underfloor heating and tap water systems to Rundbalshuset, a sustainable house built from straw bales and clay in Kassjö, just outside Umeå. The house has been designed for low energy needs with built-in renewable energy sources and passive measures to reduce dependence on the electricity grid.

Picture: ELVA Hållbara AB

About the project

Laura and Erik Vidje build their self-designed round sustainable house from straw bales and mud on a 4,000 square meter plot in Kassjö, just outside Umeå. There is also a woodshed, earthen cellar and garage on the plot. They have combined traditional and innovative solutions to build a tailored and comfortable home adapted to the local climate. In northern Sweden it can be -30ºC in winter and snow covers the ground for months, but also above +30ºC in summer with more and more drought.


They have used circular design principles in order for the property to be self-sufficient both now and in the long term. They have built with mostly local and sustainable materials and used products that can be reused or recycled, or that were already condemned to be thrown away and would otherwise go to waste. The construction is built with wooden studs, which are then filled with tightly pressed straw bales which are then plastered with clay and form the 70 centimeter thick walls.


Rundbalshuset has been designed for low energy needs with built-in renewable energy sources and passive measures to reduce dependence on the electricity grid. Thanks to recirculation of the hot water in the shower, only five liters of water are required per shower. The gray water is purified in infiltration on site while the faeces are composted and with solar cells, as well as solar collectors plus own wood, the house becomes self-sufficient in energy. In addition, they have laid a 30 m pipe two meters into the ground, which preheats or cools the air all year round, which provides an energy saving connected with the FTX system.


The large plot will enable them to grow a lot and become self-sufficient in a large part of their food, while improving local biodiversity.


Thermotech´s delivery

We have delivered both waterborne underfloor heating and tap water systems to the house and garage.


Rundbalshuset — a summary

Type of project
House of straw and mud

Thermotech´s delivery

  • Waterborne underfloor heating
  • MultiSystem tap water system

Project time
Planning and design started in 2014
Start of construction 2017
Moving in 2021
Thermotech´s delivery 2019 

The house owners themselves - Laura och Erik Vidje

Plumbing installer
Mattias Håberg VVS



In 2020, Erik and Laura started up their company ELVA Hållbara AB again, with the aim of being able to more easily organize study visits, lectures, construction courses, etc. Due to the pandemic, however, it has not been possible to carry out any lectures or study visits as planned. Therefore, they have chosen to digitize the lecture about the project. Thermotech has participated and sponsored parts of this lecture to help spread knowledge about sustainable construction.

Online lecture

More about Rundbalshuset
Instagram: @rundbalshuset


Text and pictures from: ELVA Hållbara AB