Passivhaus: What is it and why should I care?

What is Passivhaus?

Passivhaus is a voluntary building performance standard that can be applied by anyone looking to build an eco-friendly, low-energy home. Passivhaus is designed to provide a high level of dweller comfort, whilst providing ultra-low energy consumption for heating and cooling, and consistently good air quality. They are built using design principles developed by the Passivhaus Institute in Germany to achieve a quantifiable and rigorous level of energy efficiency within a specific quantifiable comfort level. SDC adopts these design principles as standard.


“A Passivhaus is a building in which thermal comfort can be achieved solely by post-heating or post-cooling the fresh air flow required for a good indoor air quality, without the need for additional recirculation of air.” – Passivhaus Institut (PHI)

Why Passivhaus?

Passivhaus provides a crucial opportunity for addressing two major challenges presently facing the UK’s housebuilding industry:

1) Building regulations are tightening, requiring more energy-efficient buildings, and targeting zero-carbon new homes.
2) Many conventional buildings designed and built in the past few years are demonstrating a performance gap (poor performance compared to predictions) in terms of:

a) energy use

b) ventilation and indoor air quality

c) thermal comfort and overheating

There are many benefits of making your home a Passivhaus:

• Extremely comfortable internal environment
• 75% reduction in space heating requirements, compared to standard practice for UK new build.
• Heating bills are typically reduced by 90%
• Helps the industry achieve the 80% carbon reductions that are set as a legislative target for the UK Government.
• Passive building principles can be applied to all building typologies – from single-family homes to multifamily apartment buildings, offices, and skyscrapers.
• Superinsulation and airtight construction provide unparalleled comfort even in extreme weather conditions.
• Continuous mechanical ventilation of fresh filtered air provides outstanding indoor air quality.
• Significantly improved air quality and thermal reduces allergies such as asthma and hay fever
• A comprehensive systems approach to modelling, design, and construction produces very resilient buildings.

What is the Passivhaus standard?

For a building to be considered a Passivhaus, it must meet the following criteria:

1. The Space Heating Energy Demand is not to exceed 15 kWh per square meter of living space (treated floor area) per year or 10 W per square meter peak demand.

In climates where active cooling is needed, the Space Cooling Energy Demand requirement roughly matches the heat demand requirements above, with an additional allowance for dehumidification.

2. The Renewable Primary Energy Demand (PER, according to PHI method), the total energy to be used for all domestic applications (heating, hot water and domestic electricity) must not exceed 60 kWh per square meter of treated floor area per year for Passivhaus.

3. In terms of Airtightness, a maximum of 0.6 air changes per hour at 50 Pascals pressure (ACH50), as verified with an onsite pressure test (in both pressurized and depressurized states).

4. Thermal comfort must be met for all living areas during winter as well as in summer, with not more than 10 % of the hours in a given year over 25 °C. For a complete overview of general quality requirements (soft criteria).

These criteria are realised through intelligent design and implementation of the 5 Passivhaus principles: thermal bridge free design, superior windows, ventilation with heat recovery, quality insulation and airtight construction.



The EnerPHit standard – for refurbishment and retrofit

It is also possible to attain the Passivhaus certification for very low energy retrofit projects. Where the existing architecture and conservation issues mean that meeting the Passivhaus standard is not viable, the EnerPHit standard for retrofit projects is slightly relaxed.

How can SDC help?

We provide a complete Passivhaus design and build solution. Our unique Passivhaus twin-wall kit home build system delivers some of the lowest u-values on the UK market. Our Passivhaus certified passive design consultants combined with our in-house sustainable architects to optimise your scheme to meet the Passivhaus standard and will work with our clients to provide sustainability consultancy on the best energy strategy and low carbon options for your the scheme.

We can offer a fixed price for:

• Initial Passivhaus Planning Package (PHPP) energy modelling of the scheme
• Architectural design -Planning, detailing and Building regulations
• Passive Slab foundations
• Superstructure – Timber frame walls, Roof and internal floors and partitions
• Warmed recycled newspaper insulation
• Triple Glazed Pasivhaus certified windows and doors
• Passivhaus Airtightness guarantee and free Air test
• Energy systems and MVHR guidance
• Project management to completion