What is a Passive House?
If you don’t know what a ‘Passive House’ is you’re in good company, most people haven’t. Passive Houses are essentially buildings which use very little energy for heating and cooling, whilst also providing a high level of comfort.
Save up to 90% on your heating costs with a Passive House
To describe a Passive House in a few words it would be ‘Exceptionally energy efficient, virtually airtight houses’. The houses are so energy efficient they can save up to 90% in heating costs.
One of the main focal points of Passive Houses is minimising air leakage from the property. In fact, for a house to be certified, ‘the building must not leak more air than 0.6 times the house volume per hour’.
How does a Passive House work?
The houses use the latest in insulation technology, triple-glazed low-E windows, mechanical heat recovery ventilation and limiting thermal bridging, being heated mostly using ‘passive’ energy from electrical equipment, people and passive solar gains from the sun.
Passive House Principles
Orientation & Shading
While Passive House projects are not dependent on solar gains to achieve thermal comfort and energy efficiency, they still benefit from careful consideration of the impact of sun paths and shading.
Form factor is important for a Passive House. A larger thermal envelope will transmit more heat per usable area and a complex shape will involve more junctions that create difficulty and cost. Keep it simple!
Windows & Doors
High-performance windows and doors are arguably the single most important component to get right in any Passive House project. Passive House certified windows are available in a number of different frame materials that satisfy strict criteria on thermal performance and airtightness.
Airtightness is central to attaining Passive House certification, but, most importantly, it is a key indicator of construction quality. Remember: a leaky building is not necessarily a breathable building and an airtight building is not automatically bad at managing moisture.
While a well-designed thermal envelope is key for achieving thermal comfort, getting the ventilation right is similarly important for feeling cosy and fresh inside. Mechanical ventilation is not mandated by the Passive House standard, but is the easiest way to meet the energy goals in hot and cool climates.
Hot Water & Heating
There are many different options available for heating: small heat pumps, direct electric or conventional boilers. Oversizing the heating system can be a waste of money and efficiency. You need very little heat in a Passive House, so keep the heating system small, efficient, responsive and simple!