Passive house is recognised as the ultimate standard in energy-efficient house construction. One which we should all aspire to, but what is it? How easy is it to achieve? And what are the cost and practical implications?
A Passivhaus or passive house, provides a high level of internal comfort while using very little energy for heating and cooling the home. A passive house is built with particular attention to the detail, the design and the construction according to principles developed by the Passivhaus Institute in Germany. The house is certified through an exacting quality assurance process.
A passive house maintains comfortable temperatures, whatever the weather. Optimal building positioning, shading and detailed modelling ensures the house is cool in even the hottest summers. With the house being comfortably warm in the winter, whilst using very little energy for heating, as a result of high-quality triple glazed windows and walls. Meaning there is no draughts, no cold spots and no condensation. Internorm is the number 1 Passivhaus window manufacture in Europe, with 9 passive house certified components.
The energy needed to heat a building is quantified by kilowatt hours (kWh) used per square metre of useful floor area per year. Kilowatt hours per m² varies from building to building depending on how well insulated they are, how efficient the heating system is, and how the residents use the building. People living in an average UK house might use around 140kWh/m²/yr for space heating. In a passive house, a target of 15kWh/m²/yr is set as a maximum energy demand for space heating. This is achieved by reducing the heat lost from the building to a minimum. The target of 15kWh/m²/yr is used because this is the level of performance that is most cost-effective over the lifetime of the building. Much below this figure pushes costs above a level where the benefits pay for themselves.
While there is evidence that the energy performance of new homes don’t match their design claims, the Passivhaus quality assurance process ensures that what is designed is what gets built. The actual energy performance is, on average, exactly as predicted by the design stage modelling using PHPP (Passivhaus Planning Package). Passivhaus buildings do not suffer from a performance gap as standard new builds.
Obviously a quality build usually attracts a premium but not necessarily. Passivhaus can be achieved with modest builds, costing much the same as a standard home. Taking into account the savings of around 90% on energy bills which can be achieved without the need for any expensive eco-products, the investment is clearly justified. There is no need for underfloor heating, and a wood burning stove would be mainly be for show. The super-efficient ventilation system is also affordable to run, and the quality of the build ensure minimum maintenance costs.
Passive houses come in all shapes and sizes and can be built to almost any budget. But attention to details is paramount, and great care needs to be taken in the actual construction, with a rigorous quality control process. A passive house can be built using different materials, such as timber and masonry and in a range of styles from period to contemporary, to suit individual preferences and the location.
Homeowners give glowing reviews about living in a passive house, quoting a healthy living environment, with a year-round ambient temperature, and clean air, courtesy of the ventilation system. Not to mention the low energy bills.
The most successful and cost effective way of achieving Passivhaus certification is by incorporating the standard into your design. Its also useful if the Passivhaus elements are included in your planning application.
Building a passive house is a team effort. Ensure you have the right skills on the project. It can be as varied as getting an experienced team that has successfully delivered Passivhaus already or learning yourself on a Passivhaus Trust course.
It would be very hard to retrofit an existing house to the exacting standards, but there is an equivalent, less rigorous, standard for retrofits called EnerPHit (the ‘PH’ is for Passive House). Where Passivhaus looks to achieve 15kWh/m²/yr for space heating, EnerPHit aims for a more realistic 25kWh/m²/yr. As older homes use more energy than the average new one, there is more potential for energy savings and a reduction in CO2 emissions – anything between 75% and 90%.
Passivhaus open days are held nationwide every November, allowing you to visit a passive house in your area. There is also a Passivhaus show at the Potton Self Build Show Centre in Cambridgeshire. Alternatively you can visit the Passivhaus Trust website, which has a wealth of information and case studies. The Passivhaus Trust is an independent, not for profit organisation and a subsidiary of the AECB. The trust has an inclusive government structure that incorporates all relevant parts of the Passivhaus process and supply chain. As well as independent experts, academics, buildings-related charities and not for profit organisations.
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"The whole process has been excellent - I really appreciate the patience you've taken on what is a huge expenditure for a passion project, working with total amateurs! You've always taken the time to answer questions, explain options and crucially, make recommendations when nativity/inexperience clouds our judgement. A real skill and something I personally have really appreciated as I feel confident that we now have windows and doors that complement our house, design and style. Without that level of consultative engagement and relationship I'm confident I would have overlooked details and made a substandard decision. Thank you!"
Mrs Trestain, Padstow
"Just a quick note of thanks to the whole team for our fab windows and doors, we are delighted with both the product and also with the whole fitting process. The lads were brilliant (it's not often you get trades in the house who leave it cleaner at the end of the day than when they arrive in the morning!!) and just quietly got on with the job. Thank you again"
Mr & Mrs Leonard, Exeter
"The pocket sliding door and gable look amazing, it’s an impressive bit of kit and it’s a revelation to be able to open the space up! I have to say we’ve been very impressed with all your teams positivity, professionalism and workmanship, from start to finish - so a big thank you…"
Mr Marsh, Exeter
"I would like to thank you for the quality of the service we have received from Aspect Windows and commend you for the care and attention that we have received throughout the process. I am thoroughly pleased with our new windows and would recommend your services to anybody who asks."
Mr & Mrs Miller, Exmouth
"I wanted to just send my thanks and appreciation. We had an install approx. 6 years ago including some bi-fold doors which in recent weeks appeared to have dropped and became very difficult to lock. I called the office on Monday and a lady took my details and quickly called me back suggesting you had an engineer locally the following day. He arrived and was extremely polite and efficient and diagnosed a broken hinge. He went back to the depot collected the replacement part, then returned to Budleigh and completed the repair. We really appreciate the speed and efficiency with which you dealt with the issue and the ease from a customer perspective. "
Mr Ashby, Budleigh Salterton
"I just wanted to say thank you for the excellent service you have provided in the planning, removal & installation of our beautiful new windows and doors. We were completely amazed & delighted at the speed of which the installation took place and the hard work put in by the installation team. They worked very efficiently and communicated with me at ease through the week so I knew their plans with each room for installation. All the windows & door look great and we have already had lots of compliments. "
Mrs Oakes-Ash, Exmouth
"We would like to thank everyone at Aspect Windows for the fantastic service that we have received on our project. From start to finish, you have been so professional and we are totally thrilled with our sliding doors and our side door. We would not hesitate to recommend you to anyone thinking of undergoing a similar project."
Mrs Moores, Templecombe
"We would just like to say how excellent the service has been from Aspect Windows from beginning to end. The salesman could not have been more helpful, we felt completely unhurried and un-pressured. The fitter was also extremely good, he was neat, careful and very respectful of our property as well as being very sociable and polite. Congratulations Aspect Windows on a really good job I wish everything in life could be so straightforward!"
Mr Foster, Exeter
"I had chosen Aspect Windows in Exeter to supply the glazing as they had a good reputation and specialised in aluminium doors windows and curtain walling. Aspect were brilliant throughout the design and fitting process, working to incredibly tight tolerances especially on the curtain walling."
Mr Abdilla, Exeter