Insulation*: Straw Bales

WHAT IS IT?

Straw (hollow stalks of cereal plants) are harvested, dried and baled. Straw bales are considered an agricultural co-product, used in many different industries.¹ In construction, they can be used as load-bearing structure* or as insulation, or as both, depending on the construction method. (See p.28, section 3.2 of this for more information.)

Prefabricated Straw Panels are available in the UK. These are pre-made, bespoke straw panels made of timber frames (load-bearing) with strawbale infills as insulation. Currently, there are the following companies supplying to the UK:

"If there was a shift to nature-based construction materials this would provide an additional income stream for farmers."

"If only 5% of the average annual wheat yield was allocated to construction, there would be 279 thousand tonnes available: sufficient straw for 38,923 homes per annum."²

(SNAB, 2022).

MATERIAL LIFE CYCLE

*BaleHaus Panels Embodied Carbon

Sources

KEY INFORMATION:

Is manufactured and available in the UK. Bales can be sourced directly from local fields, reducing transport and storage costs + emissions.³
Can be load-bearing structure or insulation (max height of building is determined by the structural design of the frame)³
Minimum wall thickness is 480mm. (see Modcell diagram)
Requires a "good hat, good boots and a good overcoat":
- Roof Overhang: 450mm
- Raised Foundations: 450mm
- 30mm lime plaster on both sides.
Prefab Straw Panels can be built up to 6-storeys high.³
The density of straw provides a high thermal mass, improving indoor thermal comfort.
Naturally breathable and improves indoor air quality and sequesters VOC's (harmful indoor pollutants).
Is thermally efficient (can be used to meet Passivhaus standards)
Easy to design for disassembly, and can be reused, composted, or used as biomass fuel.
Prefab Straw Panels increase the speed of construction on site.³
Provides good acoustic insulation.³
Highly fire resistant.³
Can last hundreds of years if built correctly.

Image Source

Challenges with building with Straw Bales

How much does building with straw bales cost?

Due to many factors including labour, bespoke design and material sourcing, there is no replicable answer to this. It might be slightly more expensive or slightly cheaper, but one must account for the savings in the building's operational costs due to straw's efficient properties.

Built Examples using Straw Bales