In 2023, legislation was proposed by the Scottish Government that all new homes built in Scotland will need to pass the Scottish version of the Passivhaus standard by 2025 (https://www.passivhaustrust.org.uk/news/detail/?nId=1176). Passivhaus (or 'Passive House' in English) is a science based energy building standard that results in extremely low energy consumption for heating and cooling. This legislation will confirm the energy efficiency requirements for custom and self-built homes as well as social housing projects.
A working group comprised of representatives from various sectors in the construction industry is developing the proposed Scottish standard. A comprehensive public consultation process is scheduled to commence in 2024 to gain feedback on the draft proposals, and the new regulations are targeted for formal implementation across Scotland by 2025. In this post, we will explain Passivhaus, why it is being introduced and what this means if you are looking to build your own home in Scotland.
A Brief History of Passivhaus
The Passivhaus (Passive House) concept dates back to the late 1980s and early 1990s in Germany. It began when researchers at the University of Lund in Sweden did pioneering work on super-insulated homes in the 1970s and 80s. In 1988, the Stuttgart Physics Institute conducted a study showing that an ultra-low energy home could be built using available materials and techniques. In 1991, the Passivhaus concept was conceived and developed by Wolfgang Feist and the Building Physics research group he headed at the Institute for Housing and the Environment in Germany.
The technical standards for Passivhaus were established, and they focused on drastic reductions in heating energy demand through a super-insulated thermal envelope and heat recovery ventilation. The world's first Passivhaus properties were built in Darmstadt, Germany in 1991, and through the 1990s, further Passivhaus pilot projects were constructed to refine the design, construction and standards. Passivhaus slowly gained momentum through the early 2000s with increasing numbers of certified projects, first in German-speaking countries, then expanding across Europe. By the late 2000s, Passivhaus had become established as a proven high-performance low-energy building standard being adopted worldwide.
Why Has Scotland Introduced Passivhaus Regulations?
Heating our homes contributes greatly to climate change. The Scotland Net Zero Project has reported that homes and businesses that are heated by fossil fuels create up to 22% of the greenhouse gas emissions in Scotland (https://www.netzeronation.scot/take-action/home-energy). Many households in Scotland are also in fuel poverty due to the rising energy costs in the cost of living crisis. The quickest way to reduce the production of greenhouse gasses and lower energy costs is to decrease the energy consumption of homes in Scotland by removing their reliance on fossil fuels.
What are the 5 Main Passivhaus Principles for Home Building?
The Scottish Government has stated that it will be introducing its own set of Passivhaus principles for home building but this guidance has not been released as yet. However, there are 5 main principles that must be incorporated into a Passivhaus build:
Excellent Insulation
This is an essential part of a Passivhaus building project as excellent quality insulation can wrap around the building, reducing heat loss, minimising emissions and reducing energy bills.
Triple Glazed Windows
Badly fitted or single glazed windows can be one of the biggest places where heat is lost in the home. Installing triple glazed windows can greatly increase insulation and keep the house cool during the summer and can add to the house valuation in the future.
Airtight Construction
A Passivhaus home should be an airtight home. Gaps should be sealed around windows, doors, pipes, light fittings and anywhere an air leak could occur. Having an airtight home can make the property warmer with no condensation or unpleasant draughts.
No Thermal Bridges
A thermal bridge is where there is a weak spot in the insulation between the house and the outside environment. Ensuring that there are no thermal bridges can reduce any gaps in insulation and keep the house warmer.
Installing a MVHR System
MVHR stands for 'mechanical ventilation heat recovery system' It is put in place to create clean air because if a home is completely insulated, the air quality could become stale.
What Do You Need to Consider Before Building a Passivhaus in Scotland?
To get the best from your Passivhaus design, there are a number of factors to consider before starting your new build project:
The Site
It is very important to get the right site for building your own home. Passivhaus constructions are designed to utilise the warmth from the sun so if you are in the North of Scotland where the weather can be more unpredictable, consider your site carefully and situate the build away from hills, trees and other buildings. You may also need more insulation, depending on your location.
The Design
Passivhaus constructions around the world come in many different shapes and sizes, but if you are looking to build a home in Scotland, it is important to consider how much heat could be lost from a larger home. A smaller more compact design may work better and be more cost effective as less insulation will be needed to create an energy efficient home. A cost effective home could also help with the house valuation in the future.
Achieving Certification
Passivhaus certification is the process by which buildings are evaluated and verified to meet the rigorous performance standards set by the Passivhaus Institute in Germany. To receive Passivhaus certification, a building design must first be modelled using the Passive House Planning Package (PHPP) software to estimate its annual heating and cooling demand. After construction, on-site testing is conducted by an accredited Passivhaus certifier to verify that the building meets the standard's requirements, including:
Air leakage test to confirm air tightness
Thermographic inspection to check for thermal bridges
Ventilation airflow measurements
Documentation review
If all criteria are met, the certifier issues the project a Passivhaus certificate and it is added to the Passivhaus database of certified buildings.
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