If the words insulation, ventilation and retrofit make your eyes glaze over faster than a double-glazed window sales pitch, you’re not alone. For many London families living in draughty Victorian terraces, chilly conversions or well-loved but energy-hungry homes, the idea of improving energy efficiency can feel daunting, confusing and, frankly, a little intimidating. Enter What the Builder Won’t Tell You – The Essential Homeowner’s Guide to an Energy Efficient, Healthy Home, a refreshingly honest new book by retrofit expert Judith Leary-Joyce that promises clarity without the jargon – and delivers it.
Released on 26 November 2025, this timely guide arrives just as homeowners are grappling with unpredictable energy bills, growing climate anxiety and a strong desire to create homes that are not only warmer and cheaper to run, but genuinely healthier places for their families to live.
Retrofit, explained like a coffee chat
Written in plain English and an easy, conversational style, What the Builder Won’t Tell You feels less like a technical manual and more like a reassuring conversation with a knowledgeable friend who has already made every mistake – so you don’t have to. Leary-Joyce has a rare talent for taking a complex, often overwhelming subject and breaking it down into manageable, confidence-building steps.
Rather than lecturing or overloading readers with data, she explains what truly matters when it comes to insulation, ventilation, heating systems and indoor air quality. Crucially, she also addresses the emotional side of home improvement – the fear of being misled, the frustration of unclear advice and the anxiety of investing hard-earned money into work you don’t fully understand.
For London Mums readers, this empathetic tone is a standout feature. The book acknowledges the very real worries parents have about creating safe, comfortable homes for their children, without judgement or pressure.
Lifting the curtain on the building world
As the title suggests, this is a candid guide. Leary-Joyce doesn’t shy away from explaining why some builders struggle to offer clear retrofit advice – not out of malice, but often due to gaps in training, outdated practices or the sheer complexity of modern energy-efficient design.
The book empowers homeowners to ask better questions, understand what good practice looks like, and collaborate more effectively with professionals. From navigating contracts and budgets to avoiding common pitfalls, readers are encouraged to take control of their renovation journey rather than feeling at the mercy of it.
This is particularly valuable in London, where housing stock varies wildly and one-size-fits-all solutions rarely work.
Healthier homes for growing families
Beyond energy savings, a major strength of the book is its focus on health. Poor ventilation, damp and mould are increasingly recognised as serious issues, especially for children. Leary-Joyce explains how thoughtful retrofit choices can dramatically improve indoor air quality, reduce respiratory problems and create homes that genuinely support family wellbeing.
Her approach is practical and long-term, helping homeowners think beyond quick fixes and towards solutions that will stand the test of time – and climate change.
A mission rooted in family and legacy
Judith Leary-Joyce’s motivation is deeply personal, and it shows. A former teacher, social worker, psychotherapist, business owner and executive coach, she brings a lifetime of people-focused skills to her writing. Now a grandmother – affectionately known as “Instagran” – she sees this work as part of her legacy for future generations.
In her own words, concern for the climate has always been about family: her children, grandchildren and the wider community of families navigating an uncertain future. When she couldn’t find the book she needed while retrofitting her own home, she did what many entrepreneurial women do best – she created it herself.
From Victorian house to Retrofit revolution
Leary-Joyce’s credibility is rooted in lived experience. Her first book, Beginner’s Guide to Eco Renovation, was inspired by the deep retrofit of her 1901 Victorian home, which reduced energy use by an impressive 75% while significantly increasing its value – a statistic that will make many London homeowners sit up and take notice.
Her work has since reached far beyond the page. Through her Instagram account @ecorenovationhome, she has grown a following from 300 to over 140,000 in under two years, sharing accessible insights on insulation materials, emerging technologies and traditional building wisdom that still holds true today. At 76, she has also become a powerful TEDx voice, advocating for collaboration between homeowners and builders to help tackle the climate crisis from the ground up.
An essential read for today’s homeowners
Published by AoEC Press, What the Builder Won’t Tell You – The Essential Homeowner’s Guide to an Energy Efficient, Healthy Home is available at Amazon in paperback and eBook formats, making it an accessible starting point for anyone considering home improvements – whether you’re planning a full retrofit or simply want to understand your options better.
For London Mums, this book stands out as a genuinely empowering resource: practical, reassuring and rooted in care for families and the future. It doesn’t promise miracles or quick wins, but it does offer something far more valuable – understanding, confidence and the knowledge to make informed decisions about the place your family calls home.
In a world where our houses need to work harder than ever, Judith Leary-Joyce’s message is clear: you don’t need to be a building expert to create a warm, healthy, energy-smart home. You just need the right guide. www.ecorenovationhome.com
Monica Costa founded London Mums in September 2006 after her son Diego’s birth together with a group of mothers who felt the need of meeting up regularly to share the challenges and joys of motherhood in metropolitan and multicultural London. London Mums is the FREE and independent peer support group for mums and mumpreneurs based in London https://www.londonmumsmagazine.com and you can connect on Twitter @londonmums
