Hemp has been used in construction for thousands of years, but it's only recently that it’s incredible environmental benefits have crept into mainstream awareness.

In today's episode, we continue exploring renewable materials. We'll investigate the design of a hempcrete extension to an existing Federation House located in the heritage listed suburb of Ashbury in inner suburban warm temperate Sydney. Architect Emily Knight, the director of Emily Knight Design shares the inside story on her AL House.

Today we'll learn about;

• the process, costs and benefits of using hempcrete in custom architectural construction,
• how upgrading the thermal efficiency of your existing home is critical for creating environmental change, and
• a wealth of other insights and practical information drawn from Emily's extensive experience.

Australian Architects can earn formal CPD hours by listening to these podcasts and completing an online quiz.

MORE INFORMATION

Find everything you need on the Renovation Collaborative website.

www.renovationcollaborative.com.au

• PODCAST Key points summary, timestamps and resource links
• FREE RESOURCES Transcript edited into clear Q&A.
• CPD Australian architects can find more information on CPD, and
• COURSES Eleven easy to read courses demystifying the entire home design and construction process.

KEY POINTS SUMMARY

1. The biggest environmental change can be effected through improving existing buildings. Currently in Australia, there is no requirement to upgrade your existing home as part of your renovation. However, Emily always encourages her clients to set aside some budget for this important work to ensure long term comfort and energy efficiency.

2. Hemp is used in construction in a range of formats. Hempcrete, as covered in this episode, also hemp blocks, hemp sprayed onto a frame and hemp panels.

3. Hempcrete walls are non-structural. They're formed up around a timber stud frame.

4. Hempcrete walls can be finished in a number of ways. They can be left unfinished, coated with natural breathing lime render, or a clear, penetrating, breathable sealer coat. Externally, it usually requires extended roof overhangs to prevent weathering.

5. In Emily's experience, the cost of Hempcrete construction in Sydney by a subcontractor was approximately on par with cavity brickwork. Historically, hemp buildings have been constructed by a community of unskilled friends and family, enabling much lower labour costs.

6. Hemp offers a multitude of benefits:

• It delivers very healthy indoor air quality.
• It's very durable and has a long lifespan.
• It offers excellent acoustic and thermal insulative performance.
• It's very fire resistant,
• It can be made airtight, and
• It sequesters carbon and is biodegradable at end of life.

INTERVIEW QUESTIONS

[00:00] Introduction

[01:21] How did you get started in sustainable design

[05:21] How did you start building with hempcrete?

[10:29] Is interest in sustainable design increasing?

[12:03] What was the project brief?

[15:13] Tell us about hemp?

[19:00] How is a hemp building constructed?

[21:51] How do the builder and hemp contractor work together?

[23:59] Do hempcrete walls need finishing on the exterior?

[25:49] Is hemp suitable in all climate zones?

[28:56] What are the insulative benefits of hempcrete?

[31:31] Did you test the airtightness of this house?

[37:16] How is hempcrete tamped?

[38:38] Is hempcrete cost effective?

[40:52] Do hempcrete walls need finishing on the interior?

[43:23] What other benefits does hempcrete have?

[45:49] What doors and windows did you use?

[47:58] What environmental materials did you use in the kitchen?

[50:05] What advice would you give on building with hempcrete?

IN THE NEXT EPISODE

Next week we continue our exploration of renewable materials.

Next week we continue exploring renewable materials and investigate the use of Durra Panel in a new, affordable and very sustainable home located on a suburban site in warm temperate Perth. I talk to architect Matt Delroy-Carr from MDC Architects, who'll give us the inside story on his Scarborough Sustainable House.

RESOURCE LINKS

EMILY KNIGHT DESIGN WEBSITE

Project Page https://www.ekd.com.au/al-house

PROJECT INFO

Builder: David Anderson https://www.davidandersonbuilding.com/

Hemp builders / contractors: Hemp Building Directory   https://hempbuilding.au/

Timber doors and windows: www.windoor.com.au

Accoya https://windoor.com.au/about/accoya/

Kitchen Cabinetry

Red Block https://www.redblock.com.au/

Paper Rock https://www.paperock.com.au/

Made from layers of paper from renewable sources and bonded with phenolic resin and heat/pressure cured, Paperock is a remarkably strong composite building material.

Furniture Linoleum

OTHER INFO

University of Tasmania – Forestry Building

Contractor: HansenYuncken https://www.hansenyuncken.com.au/project/utas-forestry-building/

Architect: Woods Bagot https://www.woodsbagot.com/global-studio/news/progress/university-of-tasmania-forestry-building-to-feature-innovative-alternative-to-concrete/

Eve Laron Architects https://heritage.engineersaustralia.org.au/wiki/Person:Laron,_Eve_Mirjam

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