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  • How to save money and energy, passively

How to save money and energy, passively

posted by The BuildHUB on 12th Feb 2014

Building your own home provides a unique opportunity to trial innovative new products and services that improve quality of life and save you a few bob too. If you’re thinking about self-building, and want to create an energy-efficient home that slashes your energy bills, then perhaps the Passivhaus or ‘Passive House’ standard is for you.
 
So what is Passivhaus...?
 
Here's the technical definition:
 
“A Passivhaus is a building, for which thermal comfort can be achieved solely by post-heating or post-cooling of the fresh air mass, which is required to achieve sufficient indoor air quality conditions – without the need for additional recirculation of air.”
 
Put simply, a passivhaus is designed so that it doesn't need to be actively heatd or cooled. This is achieved with:
  • Very high levels of insulation in the walls, floors, and roof
  • An airtight building fabric
  • Triple-glazed windows with insulated frames
  • Thermal bridge free construction
  • A layout optimised for passive solar gains
  • A Mechanical Heat Recovery Ventilation System.
Building a passivhaus requires a meticulous attention to design and construction detail, but you’ll get a home that keeps you cool in the summer, warm in the winter, and saves you money every month.
 
Passivhaus certification
 
To meet the passivhaus standard, your new home must hit these energy performance targets:
  • Specific heating demand: less than or equal to 15kWh/m²/year
  • Specific heating load: less than or equal to 10W/m²
  • Specific primary energy demand: less than or equal to 120kWh/m²/year
Certification is through the Passivhaus Institute, and whilst not mandatory, it proves that you’ve met the required standard.
 
Why build a passivhaus?
 
Here are the top benefits of a Passivhaus:
  • It saves you money - According to the Passivhaus Trust (link) you save up to 75% on your annual space heating requirements compared to a typical new build.
  • Excellent air quality - the mechanical heat recovery ventilation system installed keeps a constant supply of fresh air circulating through your home.
  • Comfort – The passivhaus strives to maintain a comfortable, even temperature throughout the home, and the super-insulated building fabric and triple glazed windows greatly reduce unwanted street noises
For more information on the passivhaus approach, visit the Passivhaus Trust, and see our case study...

Woodstock retrofit and extension, by Beattie Passive Projects
 
Project Brief: To extend and retrofit a poorly insulated three-bedroom home in Oxfordshire to the passivhaus standard, and to transform the 1970's aesthetics creating a light and contemporary family home. The project involved adding a two-storey extension to the western side of the home and also a first floor extension above the garage to the east - taking the home's footprint from 120m2 to just over 200m2.
 
Both extensions were built to passivhaus standard whilst the shell of the existing home was retrofitted with the Beattie Passive continuous insulation system. The resulting airtight box was complemented with high-performance windows as well as a mechanical heat recovery ventilation system that provides a steady flow of fresh air throughout the home and mitigates the need for a traditional heating system.
 
Both extensions were constructed using materials recycled from a previous Beattie Passive R&D project, further boosting the homes eco credentials and also meeting the client's sustainability requirements:

"We’re delighted to be getting the best of all worlds: we’re significantly increasing our living space and hugely improving our energy efficiency, while also improving and updating the aesthetic appearance of our home. Not only is Beattie Passive technology cheaper than traditional building methods but it’s also important to us that Beattie Passive use materials which are readily available from sustainable sources”.