HBDesignGreenHome_SCa

How to Design a ‘Green’ Home

All too often sustainable solutions are used only as a means of reducing energy bills. Charlie reveals how these features could improve the quality of spaces too.

For most, the driving force behind building a low-energy home is saving energy and, therefore, money. Undoubtedly the idea of saving the planet comes into it, but the reality comes down to low energy bills.

My design work is focused on new builds, extensions and refurbishments, all driven by a desire to be as sustainable as the client, brief and budget will allow. Through this I’ve come to believe that the reason for the take-up of sustainable building techniques is solely concentrated on money saving and payback, but people should instead be investing more in airtightness, insulation and triple glazing to create quality spaces. Still, calm, healthier and quiet — properly built, low-energy spaces are far nicer places to live. Once you’ve experienced low-energy housing you will never want to live in a draughty, cold old house again.

Comfortable, good for wellbeing, lower bills and doing your bit to conserve the planet — it sounds too good to be true. The downside is that while cheaper in the long run, low-energy construction costs more upfront. There are, however, some simple sustainable design principles that can be adopted to help make your home green.

Smart Design

One of the best things to come out of the eco sector is thermal modelling. This is the ability to use computer programmes to test the energy, thermal and water performance of a design as it evolves, and allows designers to optimise a building’s shape, orientation, windows and insulation to passively use the sun to do as much heating and lighting as possible. It goes hand-in-hand with a fabric-first approach rather than focusing, as many do, on how to heat the house through low-carbon technologies such as heat pumps, photovoltaic panels or biomass boilers. I would never design a new house without using thermal modelling to inform the process.

Overheating

All these homes with large south-facing windows and lots of insulation are wonderful, but many new builds suffer from overheating. With our climate set to warm considerably over the next 50 years this is only going to get worse. Test your home for possible overheating at the outset using thermal modelling and design it out at an early stage.

Size

The bigger the house, the bigger the bills (we calculate energy consumption through kW/m2/annum) — so try to make internal spaces work harder for you rather than just creating more rooms. Small can be beautiful and this will allow you to spend more money per m2 to get better quality spaces.

Insulation

It certainly isn’t sexy, but to create super comfortable low-energy homes, insulation is your biggest asset. Critically we are not talking about a few tatty layers of fibreglass in the loft — we are talking a minimum of 300mm-thick insulation which is properly installed. It is a case of insulating as much as possible, and then some more!

Cold Bridges

The key to insulation is lots of it, but you must also have total continuity. Any gaps or bits of structure (lintels, masonry, timbers) that bridge the insulation layer not only lose heat but moisture condensates on the resultant cold spots too. This often leads to mould – a big health risk – so you have to be very careful that your insulation layer is carefully designed.

Windows

Windows are important to get right, especially as they are replaced so infrequently. A house will usually go through multiple boilers before any of the windows are replaced, so opt for triple glazing for new builds and at least double glazing for existing homes. It is not just the quality of the windows, but how they are fitted is equally important. Air leakage around windows is a big problem and using the right foams, sealing tapes and fixings is critical.

Airtightness

After insulation, airtightness is vital. This means sealing up all the gaps and holes in your building. Draughts and air movement within a dwelling have a huge impact on the comfort of a home. The perfect internal temperature for most in a well-sealed, draught-free house is 19°C, but if there are draughts then achieving 21°C is required for a comfortable temperature. This seemingly small rise in temperature will have a big impact on your comfort and energy bills.

Heat Recovery

After a house has been highly insulated and sealed, the biggest source of heat loss will be ventilation. People need lots of fresh air to be healthy and to provide this and maintain airtightness you need a mechanical ventilation heat recovery (MVHR) unit. This is a system that extracts warm, moist air from bathrooms, kitchens and utilities by passing it through a heat exchanger to preheat fresh air from the outside which is then pumped into the bedrooms, sitting rooms, etc. It provides up to around four times the ventilation rates in a normal home and filters the air for dust, pollen and pollutants. In a well-insulated airtight house it will halve energy consumption and give fresh, warm clean air — it’s one of the best bits of technology to come into the low-energy sector.

Air Quality

In terms of creating low-energy, comfortable but also healthy homes, good internal air quality is crucial. MVHR systems help by upping the ventilation rates, reducing moisture and filtering air that comes into the house, but I am also always very careful to try and specify low toxicity and low off-gassing materials. My rule of thumb is that if I would eat my dinner off it, I will put it in a house! Think about reducing the use of MDF, particleboard and petroleum-based products and consider materials with low toxin levels instead.

Stay Positive

It is easy with all the additional complexity these issues bring to lose sight of the fact that your house should be joyful and inspiring. Sometimes low-energy architecture can become a little too worthy and rational. You need a bit of magic and sparkle in a project — don’t let low-energy concerns kill that. Whether you’re dealing with a new build or refurbishment, low-energy homes are not easy to achieve but once you do it, you’ll never go back. Super sleek £50,000 kitchens and cinema rooms are the luxuries of today; low-energy homes are the luxury of tomorrow.

  • IMG_5296 16/10/2017Getting started It’s always exciting when a project starts on site. Here the intention is to retain the existing 1960s form and extensively remodel the interior. Load bearing walls have been removed to open up the interior and make once unusable spaces usable
  • You&Yours 13/10/2017You & Yours Catch Charlie on BBC Radio 4’s consumer affairs programme You & Yours today at 12.15pm, where he’ll talk about the trend for improving your home rather than moving home.
  • 4 12/10/2017Best laid plans Charlie’s new show, Best Laid Plans starts on Channel4 this coming Saturday afternoon, 4.30pm. Charlie and property developer Sophie Morgan help couples undertaking large scale renovations solve their design dilemmas. Get the kettle on!
  • IMG_9429 10/10/2017Stripping back Work has started on transforming the skeleton of an old bungalow which will provide the shell for a new two-storey family home. Window openings frame the views across the countryside beyond as the new polished concrete flooring goes down.
  • IMG_3089 02/10/2017Re-store This cottage near Burford has been re-roofed, re-pointed and under-pinned. Short of being totally re-built, the corner of the building has been removed to make way for a large window opening for what will become the snug. The concrete slab for the extension
  • 170928_Section A-A 25/09/2017Planning permission Planning permission has been granted for us to convert two tired bungalows in to a future-proofed family home. We will now start detailing the building to fit it in/on the site’s challenging topography.
  • HBR2017 16/09/2017Homebuilding & Renovating Show The Homebuilding & Renovating Show  is back in London at the Excel Centre between 22nd and 24th September. Charlie will be in the Self Build Theatre at 12.30 giving a Beginners Guide to Building a Low-Energy Home, then again at 2pm, with A Step-by-Step Guide
  • Proposed ElevationsSW&SE 12/09/2017Conservation Praise We’ve just submitted a planning application for this family home in the woods on the outskirts of Ledbury. The principle building conservation officer was so impressed he stated that they would, ‘Recommend Approval with conditions: The proposals are for a
  • Whole Building 05/09/2017Permission received at Graven Hill Our first project at the exciting self-build development Graven Hill near Bicester has received it’s plot passport compliance – basically the same as planning permission. Good news!
  • IMG_8710 31/08/2017Finishing the foundations at Beanacre We’re out of the ground and the foundations have been finished at Beanacre. For a more in depth account of how it happened, click on this link to Charlie’s blog at the Homebuilding & Renovating website.
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