Bronwyn Barry from One Sky Homes explains the evolution of windows and why modern windows are really pieces of equipment. She also shares what's involved when it comes to choosing high performance windows for a project.

Jason Orme, editor of Homebuilding & Renovating, shares some of the key challenges that self-builders face and what can be done to make sure they don't become pitfalls. He also explains how custom build might be a good option to explore for those who want a bespoke home but without the same level of risk.

Cath Hassell from ech2o consultants shares why saving water - particularly hot water - is something we should all be doing. She also explains how we can achieve this in our houses through a mixture of technical solutions and behaviour change.

*A lot of the information in this episode is specific to the UK. This is because it became difficult to keep answering in general world terms because in each country it would be slightly different.*

Lloyd Alter, Managing Editor of TreeHugger, explains how worldwide trends in green building have developed. He also shares his tips for self build success as well as some pitfalls to avoid.

Architectural designer Wilf Meynell explains the concept of environmental design and why it is not the same thing as low energy design. He also shares how he has tried to balance these two approaches in one of his upcoming projects, Springfield House.

Douglas Kent from The Society for the Protection of Ancient Buildings explains how to look after period properties and what advances are being made with conservation techniques in order to achieve greater energy efficiency.

Tim Hulse from EcoVert Solutions explains what insulation is and why there are often trade-offs to be made when selecting insulation.

Architect, planner and author Graham Towers explains the fundamentals of housing density and why we really need to get it right in future developments.

Mark Wilson from BuildingDesignExpert.com shares why he believes there is no such thing as a sustainable material and why it is our environment we are really hoping to sustain.

Architect and author Sarah Susanka shares why scale is such an important aspect to consider when building a house. She also explains how a 'not so big' philosophy can be applied in many areas of our lives.

Mark Westcombe, one of the founding members of Lancaster Cohousing, explains the cohousing concept and why creating an intentional community like this has many benefits.

Mike Jacob from Trunk Low Energy Building provides an insight into the benefits of hiring a project manager for a house build. Also Ben Adam-Smith reflects on the UK Passivhaus Awards 2013.

Paul Jennings from Aldas explains why airtightness is an important factor to grasp when constructing an energy efficient home. He also shares how forward planning, attention to detail and teamwork are imperative for achieving good airtightness results.

Elrond Burrell from Architype helps bust some of the common myths that surround the Passivhaus standard.

Jonathan Hines from Architype explains the concept of eco-minimalism and also the very different approach that guides them as a business. We discover how this design philosophy has helped shape an exciting new scheme of 150 Passivhaus homes for the village of Kingstone, Herefordshire.

One the day this podcast was published the development - in conjunction with ArchiHaus - was granted planning approval! N.B. Our interview with Jonathan was recorded on 20th March 2013.

Kingsley Barraclough shares his experience of building a house and explains why he decided to use structural insulated panels (SIPs).

Mark Saich from Green Building Solutions gives an insight into why straw bale building is becoming popular. He also addresses some of the issues that we may harbour around the safety and durability of this low impact and low carbon material.

Matthew Cutler-Welsh from Home Style Green explains some of the challenges of creating sustainable urban systems. He also shares his goals as a podcaster, including championing healthier, better homes for New Zealand.

Andy Simmonds from Simmonds Mills Architects explains ventilation in the home, why it's important and what the options are if you're looking to retrofit a property for energy efficiency.

Mark Brinkley considers why the UK has the smallest proportion of self build across Europe and what changes might need to occur if we wanted to adjust the balance. Mark shares why Germany's system is more likely to lead to higher standards and communities that embrace development.

London's Ecobuild has just concluded for another year and Ben Adam-Smith shares his experience of the event. In this episode he chats to four people he met there - Janet Cotterell from Passivhaus Homes, Jon Bootland from the Passivhaus Trust, Jo Gooding from the UK Cohousing Network and Robert Stern from Litmus Films.

Justin Broadbent from isoenergy explains what a ground source heat pump is and how it could be used as a solution to make a period property energy efficient.

What's more important - preserving heritage architecture or retrofitting it to high energy efficiency? In our first forum on a Google+ Hangout we discuss some of the issues.

The Panel

Writer and blogger Roger Hunt (who appeared in our 10th podcast)

Writer and Passivhaus consultant Adam Dadeby from Passivhaus Homes (who appeared in our 5th podcast)

Homeowner Ross Atkin (who has recently retrofitted his Victorian house)

Ben Adam-Smith shares an idea he has about using the Internet to communicate the need for incremental lifestyle change as an action to combat climate change. This one-off episode focusses on how you could use content marketing to get your message across. Cesar Abeid from The Construction Industry Podcast is Ben's guest and helps explain how content marketing works.

Bill Butcher from Green Building Store shares his approach to creating a low energy barn conversion by building a box within a box. Stirley Community Farm will meet the EnerPHit standard.

Jason and Lucy Reeve share what preparation was necessary to commission their new-build home and Ben Adam-Smith considers what's more important in renovation, preserving the past or creating a sustainable future.

Dr Derek Taylor from Altechnica weighs up the pros and cons of various renewable energy sources and shares his thoughts on whether you should be generating at home. He also talks about his role in creating one of the UK's most energy-efficient homes.