A Proactive Approach to a Passive House

EPC - Passive House

A proactive approach to a Passive House

‘Passive House’ is a standard for a cost-effective, low-energy construction concept that produces buildings with remarkable energy efficiency qualities without compromising on comfort.  

With all of the necessary information published freely on-line, it is claimed that any competent architect can design a Passive House. The standard is also relevant to non-residential buildings such as schools and offices. While it is most simply achieved with a new-build, it can also be successfully applied during a major building renovation.

Passive House buildings combine the use of energy efficient materials, a very high level of floor, window, roof and wall insulation and an airtight design. They are designed to be ‘thermal bridge free’, meaning the insulation has no cold corners or weak spots, reducing any problems with condensation. Ventilation is nevertheless essential, and an unobtrusive system supplies constant fresh air to maintain high levels of internal air quality without creating draughts. It incorporates a highly efficient heat recovery unit that captures heat for re-use in the building.

The designers ensure that the building makes such efficient use of the sun, internal heat sources such as domestic appliances and heat recovery that a conventional heating system is unnecessary, even on the coldest days of winter. This is what defines a Passive House. During the summer, passive techniques such as strategic shading help to keep the building comfortably cool.

Tests and calculations on existing Passive House dwellings are producing some impressive data. Measurements carried out on more than a hundred Passive House properties in central Europe as part of the European Union’s CEPHEUS project showed average energy savings of approximately 90% by comparison with traditional building stock, and 75% savings against new-build equivalents.

As a result, Passive Houses are environmentally friendly by definition. While some additional energy may be required initially for their materials and construction, this is insignificant by comparison with the energy savings they enable throughout the life of the building.

Similarly, the necessary financial investment in high quality materials and design required by the Passive House standard will be offset by the greatly reduced cost of installing and running heating and cooling systems. Calculations for German Passive Houses suggest that initial construction costs are now only approximately 5% higher than those of a comparable traditionally built house. Payback periods of course depend on the size and construction cost of the building, but under most circumstances the reduced running costs are likely to offset the construction costs in two to three decades, even allowing for loan repayments.

The Building Research Establishment (BRE) is one of the certifying bodies for Passive Houses, and there are fewer than a hundred of its Passivhaus buildings in the UK. The ‘Sleepy Dorset’ blog (here) tells the story of one family’s self-build Passive House since 2016 and its successful achievement of Passivhaus status. It relates how the house performed in Dorset’s coldest winter weather for many years in March 2018, and how the family awoke each morning to a comfortable 18ºC without any heating, despite outside temperatures of -6ºC and thick snow.

The Biomass Boiler Alternative

Biomass Boiler

An Introduction to Biomass

Households that are not keen on modern renewable energy technologies might prefer a more traditional wood burner or biomass boiler. Man has been burning wood to provide heat since he first harnessed the power of fire in his cave, but a modern biomass boiler offers a more sophisticated solution to home heating.

Simple wood burning stoves provide heat and a focal point for the main room and can include a back boiler to run small-scale central heating and hot water systems. A biomass boiler works like a normal gas or oil boiler but they burn renewable biomass instead. New generation systems are easy to use and deliver greater than 75% energy efficiency using pellets or properly dried wood.

Systems are available for a range of fuels, including logs, wood chips, sawdust, grass-derived biomass pellets or even peat. The choice of fuel will be dictated by the availability and price of a reliable local supply and the type of storage available. The greatest savings are made when buying in bulk so to get the best deal a significant amount of storage space is required.

Pellets are much easier to transport and store than logs, and provide a more controllable heat. Pellet-fuelled biomass boilers are available with automatic fuel feeders and they can be programmed in much the same way as conventional gas boilers. Log-burning stoves and boilers involve considerably more work and are less controllable.

The installed cost of a wood burning stove will be around £2,500 to £7,500, depending on the model and the availability of a flue. The price of a full biomass boiler system is greater than that of a comparable gas boiler at between £10,000 and £20,000, depending on model, size and ease of installation.

After the initial outlay, the system should reduce energy bills over time, with some studies suggesting that a biomass boiler can save the average household up to £800 a year when compared with standard electric heating, or up to £210 a year compared with an old G-rated gas boiler. However, at typical 2018 prices, running a biomass boiler is likely to cost more than a modern condensing gas boiler.

To maintain efficiency, the flue will need to be cleaned annually at a cost of around £50. Another downside is the need to remove and dispose of ash. Some biomass boiler systems have automatic ash removal and compression systems that make the job easier.

Government support is available for the installation of a biomass boiler or biomass stoves with a back boiler through the Renewable Heat Incentive scheme. The income depends on the system and the amount of energy it produces but the payment for a biomass boiler in a four-bedroom, detached house may be nearly £2,000 per annum. To be eligible, the property must have a compliant EPC that is less than two years old.  There is a calculator and information on the BEIS website here.

Minimum Energy Efficiency Standards (MEES) for Landlords


The requirements for private rental properties are being tightened under the law, as the Government brings the various provisions of The Energy Efficiency (Private Rented Property) (England and Wales) Regulations 2015 progressively into force in order to promote a new baseline minimum level of energy efficiency.

From 1 April 2018, landlords must have implemented energy efficiency improvement measures to ensure that privately rented properties in England and Wales achieve an Energy Performance Certificate (EPC) rating of E or better before they agree a new tenancy with existing or new tenants.  This requirement will be extended to all domestic rental properties in April 2020, whether or not there has been a change in tenant, and similarly to non-domestic rental properties from 2023.

This is known as the Minimum Energy Efficiency Standards, or MEES.

The required improvement measures referred to include any energy efficiency enhancement work that qualified for the Green Deal, and the installation of a gas supply provided the property is within 23m of the main.

The requirement will not apply to properties that are exempt from needing an EPC, such as some listed or temporary buildings, furnished holiday accommodation and properties that have been let continuously on a Regulated Tenancy to the same tenant since before 1 October 2008.

A landlord may be able to gain an exemption from the requirement under certain limited circumstances. These include:

  • Where all practicable energy efficiency improvements have been implemented but the property still fails to achieve EPC E banding.
  • A necessary measure cannot be implemented because it would have a negative effect on the structure or fabric of the building.
  • Third party consent is required to implement a measure, but it cannot reasonably be obtained.
  • A Chartered Surveyor’s report demonstrates that the measures would reduce the value of the property by more than 5%.

Exemptions may also be possible where landlords can demonstrate that they have been unable to access funding such as Green Deal, Energy Company Obligation or other grants to cover the full cost of installing the recommended improvements, though the details of this are subject to an on-going Government consultation exercise.

Special arrangements are also in place to provide time for landlords that have recently inherited properties to bring them up to the required standard.

Any exemption must be registered on the National PRS Exemptions Register on the BEIS website by 1 April 2018. The exemptions are for five years, during which time the landlord is expected to make further attempts to bring the property up to at least band E status, though a further exemption can then be applied for if this has not been reasonably possible. Exemptions do not pass with title, so a landlord buying a property with an existing exemption will need to apply for a new one.

The Regulations will be enforced by local authorities, who can issue compliance notices and demand copies of relevant paperwork.  They can hand out fixed penalties for non-compliance, and these can reach a maximum of £5,000 per breach. 

The Government’s guidance on the requirement is available here.