Passivhaus overheating shouldn’t happen: it’s one of the criteria of the international Passivhaus standard. Even so, people sometimes ignore this requirement during the early stages of the design process.
Ground-breaking housing scheme captures one developer's journey to passive ... The just-finished second phase of Durkan Residential's ambitious Silken Park scheme in south-west Dublin bridges the gap between two extremes: while phase one was built to the 2002 building regulations, phase three - which will break ground next year - will comprise 59 passive certified units.
Thermal mass 'Thermal mass' describes a material's capacity to absorb, store and release heat. For example water and concrete have a high capacity to store heat and are referred to as 'high thermal mass' materials. Insulation foam, by contrast, has very little heat storage capacity and is referred to as having 'low thermal mass'.
Passive House is a building standard that is truly energy efficient, comfortable and affordable at the same time. Passive House is not a brand name, but a tried and true construction concept that can be applied by anyone, anywhere.
The cheapest and cleanest energy choice of all is not to waste it. Progress on this has been striking yet the potential is still vast. Improvements in energy efficiency since the 1970s in 11 IEA member countries that keep the right kind of statistics (America, Australia, Britain, Denmark, Finland, France, Germany, Italy, Japan, the Netherlands and Sweden) saved the equivalent of 1.4 billion tonnes of oil in 2011, worth $743 billion.
The government's cynical recent energy policy announcements represent a dereliction of duty to the vulnerable and to future generations. There is an alternative, argues award-winning passive house architect Justin Bere - and it's beautiful.
Many of the UK's elderly citizens and low income residents cannot afford to maintain healthy conditions or basic levels of comfort in their homes, while those who are better off often cosset themselves in over-heated homes burning excessive amounts of precious and polluting fossil fuel. Everyone complains about the cost of energy, politicians wring their hands and try to sound as if they have a plan, but little is done to improve the UK's domestic and non-domestic buildings to make them more affordable to run.
"Those who peddle minor gestures in sustainability as if they are an alternative to passive house are either lacking in real knowledge, or simply playing confidence tricks on the public."
In a world where there is a rapidly growing population demanding a share of ever fewer resources, it is unrealistic folly and indeed utterly foolhardy to think that the answer to the high fuel consumption of our buildings is simply to outsource new power stations on guaranteed repayments to meet the unchecked projected future growth in demand. Yet this is exactly what the UK is currently doing. Through sloppy thinking, the UK is mortgaging the future; locking the younger generations into a level of expenditure on fuel that will most likely be completely unaffordable for them. Effectively they will be trapped in a situation with no affordable way out. What is utterly unforgiveable is that the reason for this is that the current generation doesn't want to feel any of the pain of transition. But transition will have to happen in the end and the longer we leave it, the more painful - or catastrophic - it will be.
Yet those of us in the passive house community have demonstrated that there is a solution that can deeply reduce overall energy demand in both new and existing buildings by 80 or 90% while at the same time creating exceptionally healthy and comfortable buildings. New passive house buildings can be built for little or even no extra cost if design priorities are realigned with an energy saving imperative. But even where there are additional costs, such as in passive house retrofits, the costs can be paid back in a lifetime so that future generations are handed an affordable and beautiful solution.
The UK can look back with pride at how its population pulled together and responded effectively to national emergencies in the 20th century. Once again, and as much as at any time before, we need to respond with effective action to what I believe is an even bigger emergency than those faced by previous generations.
Effective action will include re-building the respect for vocational skills, the passion for making things to the best of our ability and to world-beating levels of excellence. It will include renewed respect for world-class engineers and engineering businesses. It will include a transformation of the construction industry from one focussed on what it can take from society, to one focussed on what it can give to society.
All this requires an honest, clear vision which I believe all of us in the passive house community have, and which we must promote. We must point out that those who peddle minor gestures in sustainability as if they are an alternative to passive house are either lacking in real knowledge, or simply playing confidence tricks on the public.
In An Introduction to Passive House (RIBA Publishing, £27.99), I present facts and arguments that attempt to show why passive house is the best form of building for people's health, comfort and general well being, for every age group, for fantastically low energy use, for very low whole-life costs, for the environment as a whole and for the future of the planet.
Embracing passive house technical methods does not mean that we have to turn our backs on beautiful architecture or light-filled, flowing spaces. Passive building techniques give us the opportunity to hold on to the uplifting aesthetic tenets of the very best 20th-century buildings, while at the same time transforming our technical abilities to make social progress and beauty possible in a world where excessive consumption is no longer tenable.
An Introduction to Passive House shows that the economics of passive house are clear. While shifting priorities is a simple lifestyle choice for many, for others the help of responsible, intelligent and forward-looking governments is needed in order to make it easy for individuals and organisations to make steps now, for the benefits of both themselves and of society at large, now and in the future.
Passive house is emphatically not a product, nor does it require designers to use particular products. The Passive House Institute offers manufacturers technical assistance to improve their products, and provides quality assurance certification, but passive house buildings can be built without any certified products. Passive house is a standard and an advanced method of designing buildings using the precision of building physics to ensure comfortable conditions and to deeply reduce energy costs. It does what national building regulations have tried to do. Passive house methods don't affect "buildability", yet they close the gap between design and performance and deliver a much higher standard of comfort and efficiency than government regulations, with all their good intentions, have managed to achieve.
The in-use performance data from passive house buildings shows that to provide comfort, to save energy, to reduce bills, to protect people from fuel poverty, to reduce excess winter deaths, to save money in the long run and, arguably most importantly, to reduce CO2 emissions, it is difficult to escape the conclusion that deep, energy-saving passive house retrofits and new-builds must become the norm. A deep, energy-saving retrofit programme will create jobs now at the same time as saving money on fuel imports, both now and long into the future. Vast amounts of money can also be saved by reducing the need for new power stations and for long-term storage of nuclear waste, and by reducing the serious impact upon the National Health Service of the UK's dreadful, damp and draughty buildings.
In concluding I will repeat the question that visitors to passive house buildings seem to ask more than any other: Why aren't all buildings built like this?
An Introduction to Passive House by Justin Bere (RIBA Publishing) is available now at RIBA Bookshops (ribabookshops.com/passive)
Bere, J. (2014) ‘A Beautiful Solution’, Passive House + , Issue 5, UK Edition, pp. 20.
The new CREST centre will comprise of three areas; the Hub, the Research & Development Lab and the Pavilion. The Pavilion will be newly developed while the Hub and Research & Development lab will be integrated into the existing Skills Centre building; with the work on the Hub area recently completed.
The Hub will form the central office area within the CREST centre and will comprise modern office and meeting space where the CREST team will meet with companies to discuss their requirements and outline the services available.
From the very outset it was made clear that sustainable design was key to the successful completion of the entire CREST project, this responsible approach was to reflect the innovative aspirations of the CREST project. We are pleased to be associated with our client, South West College, who are striving to create a sustainable centre that will form a benchmark for construction projects in the future.
The new pavilion project is the one of the most sustainable projects in the UK and will be the first commercial building in Ireland to have the following three sustainable credentials:
- Passivhaus Certified for Energy efficient envelope and ventilation system
- BREEAM excellent in terms of the BRE sustainable benchmark for UK commercials buildings
- The building will also be Carbon Neutral, this means that the building can provide, by renewable energy, it own source of heat and lighting.
Whilst a combination of these sustainable criteria has been attempted in other parts of the UK, this will be the first example in Northern Ireland or Ireland and will become a benchmark building for sustainability.
The Hub element of the project comprises of several meeting rooms, a waiting area, small kitchen and computer desk. During the fit out of the Hub office area, where ever possible and feasible, recycled components and sustainably sourced materials where used.
A palette of recycled materials has been used to decorate the meeting rooms. Bangor blue slates, reclaimed from the Belturbet Convent of Mercy (demolished in 2008) and reclaimed Florencecourt brick from a house in Enniskilen (demolished 2008) have been re used on the walls of the meeting rooms. Pitch pine floor boards from the Belturbet Convent of Mercy have been used to differentiate the meeting rooms from the rest of the Hub.
The reception desk of the new hub has been created using the same pitch pine as has been used on the floors of the meeting room; the desk is supported on gabions of handpicked stone from the only slate quarry in Ireland.
The timber cladding used for the cladding walls in the Hub is reclaimed scaffolding boards that were used as shuttering on the A5 road extension project. Scaffolding racks and poles are used to support the desks and other furniture that has been created bespoke for the project.
The palette of materials combined with the exposed duct work have created an industrial warehouse type aesthetic that is illuminated with low energy lamps to further increase the sustainability criteria. The design utilises these materials to create a tactile, efficient and user friendly hub for a functional educational facility. The project was completed in February 2014.
Many people appear confused about how PassivHaus and the code for sustainable homes can run in parallel, 'Does one compliment the other?’
To obtain the definitive answer, we need to remember that us that Passivhaus focuses on building fabric and performance without the use of renewable technology. Typically a PassivHaus will achieve code energy rating of level 4 or 5. This means that it is an ideal methodology for achieving the higher level of the overall code rating, whilst also minimising the cost of renewables.
Principles And Performance
The term 'PassivHaus' refers to a specific construction standard for buildings which have excellent comfort conditions in both winter and summer. These principles can be applied not only to the residential sector but also to commercial, industrial and public buildings. For houses, it is claimed that this is the world's leading standard in energy efficient construction. They are designed and built using a step-by-step approach with efficient components and a whole house ventilation system to achieve exceptionally low running costs to create something which is comfortable, healthy and sustainable.
There's an interesting article in Green Building Magazine www.greenbuildingpress.co.uk written by Justin Bere about a talk given in London by Wolfgang Feist who founded the German PassivHaus Institute in Darmstadt.
The fundamental objective of PassivHaus design is unambiguously to cut energy consumption and to provide accurate design tools to measure the expected energy consumption in a clear, accurate, numerical way. Germans really don't have time for vagueness and are aware of the requirements set out in UK Building Regulations. However many of our Code level features are incorporated, no one can circumnavigate the essential requirement to produce a building designed to use less than 15kWh/m2/annum supplementary heat and no more than 120 kWh/m2/annum primary energy [total of heating, lighting, hot water, appliances and any cooling). No box ticking wood chip boiler - nothing will let the PassivHaus architect, developer or builder circumnavigates this fundamental, verifiable bottom-line requirement for PassivHaus certification.
The simple techniques necessary to achieve PassivHaus design are: Insulation [typically 30cm thick]; PassivHaus windows [airtight, triple glazed with thoroughly insulated frames achieving an overall U-value of 0.8 including the frame]; Airtight construction [max 0.6 air changes/hr under 50 pascals pressure] with very efficient mechanical heat recovery ventilation. Assuming that these three main performance targets are met, together with detailing to eliminate cold bridging and numerous other detailed requirements prescribed by the PHPP software, it is possible to eliminate the need for a boiler and the need for radiators or underfloor heating.
Comparing certain other UK building codes with the PassivHaus approach highlights difficulties in the UK codes that have been introduced in relative haste. By contrast the PassivHaus code has passed the test of time and Dr Feist is very careful to ensure that it remains truly robust. It is the very robust nature of the concept and the software that led the RIBA in a sustainability review to originally describe PassivHaus as 'The emerging European Standard.' Now there are about 17,000 buildings have been constructed worldwide, typically achieve an energy saving of 90% compared to existing housing principles.
The NHBC Foundation and Zero Carbon Hub have published 'A practical guide to building airtight dwellings'. It brings together the experiences of those who have already got to grips with air tightness for the benefits of designers and builders who have not. It provides solutions for common air leakage paths. Clearly, changes in the Building Regulations have now made air tightness an issue which cannot be ignored.
The Denby Dale Project
Typically, PassivHaus buildings are built using timber-frame construction or blockwork wall with external render. Green Building Store has succeeded in adapting the PassivHaus approach to British traditional building methods - by creating the first certified PassivHaus in the UK to use traditional cavity wall construction. Earlier this year the Denby Dale PassivHaus project in West Yorkshire received its official PassivHaus certification.
The project - built by Green Building Store's construction division Green Building Company - has pioneered the combination of low energy PassivHaus methodology with standard British cavity wall construction and building materials. Bill Butcher, Director of Green Building Store, said, "We chose cavity wall construction because most British builders are familiar with the technique and materials could be sourced easily from any builders' merchant. Cavity wall also met Yorkshire planning requirements for stone exteriors and was affordable for our clients. In addition, masonry construction, including cavity wall, offers a 'cave effect' which acts as a thermal mass, helping to keep temperatures stable in winter and summer".
It requires minimal heating - using 90% less energy for space heating than the UK average; £141 K build cost for the 118m2 three-bed detached house. Green Building Store's technical film 'PassivHaus low energy building in the UK' for building professionals is freely downloadable from www.greenbuildingstore.co.uk. The 60 minute film covers all stages of construction of the Denby Dale project.
What are the challenges?
Achieving the required level of air tightness, minimising the risk through good design and specification.
Is it costly to build?
European experience suggests an extra 6% is likely. There are not yet enough UK houses to make a proper comparison, although BRE is advising on a London project which has achieved PassivHaus for the same cost as a typical social housing one.
Are PassivHaus products widely available?
Yes but windows have at present time to be imported; they have generally been the reason for higher costs.
Will adopting PassivHaus facilitate compliance with buildings regs and the Code for Sustainable Homes?
Yes. If a compliant design specification is derived from PHPP [the PassivHaus Planning Package] and transposed into SAP, a 30-45% improvement in carbon emissions can be realised - without the use of heat-pump, biomass or other low carbon or renewable technology.
According to the Energy Saving Trust's Chief Executive Philip Sellwood, almost a third of new homes are still failing to meet energy efficiency guidelines. He told the BBC " ... the Government's 'Code for Sustainable Homes' is not being adequately enforced, giving cause for real concern. Our building regulations in the UK are among some of the toughest in Europe, but they are extremely poorly enforced as far as energy efficiency goes".
David Arendell, MD of roof ventilation specialist Klober feels the situation in respect of building air tightness gives grounds for even greater concern. He commented, "In the light of the EST's comments on energy efficiency, it is fair to assume that the level of understanding of how best to achieve air tight construction remains poor.
This is despite the fact that the phrase 'Build tight, ventilate right' has become synonymous with the strategy to achieve low energy buildings. If we don't understand how best to achieve the right balance of air tightness and controlled ventilation, we run the risk of perpetuating condensation problems within the roof space and building fabric. With every upgrade in insulation standards, so the risk increases.
Delays in consultation on Approved Documents Land G have prompted deferment in CSH 2010 until the end of the year, but the clock is undoubtedly ticking towards an ultimate target whereby all new homes achieve CSH Level 6 (effectively zero carbon). However, with house builders having lobbied consistently for tighter definition of how 'zero carbon' can be achieved, the Zero Carbon Task Group was set up.
There is some evidence to support such calls for redefinition. Research carried out in 2007 by the Richard Hodkinson Consultancy, for example, showed that 'PassivHaus' (a Europe-wide Standard with stringent air tightness requirements managed by the BRE and the Energy Saving Trust) would not actually meet CSH 3.
CSH assessment uses the Standard Assessment Procedure (SAP) test to calculate energy performance, and for a number of years there have been questions over the efficacy of the test, especially in relation to more thermally efficient buildings.
In terms of roof design, the requirement already exists for new public sector housing to meet CSH 3. The impetus towards 'zero carbon' will be reinforced when the equivalent of CSH 3 is incorporated into Building Regulations for England and Wales (some authorities indeed have already adopted this requirement). In Scotland, where many elements of the Code have already been incorporated into Building Standards, similar improvements are planned.
Of the nine categories within the CSH method of assessment, that for 'energy and C02 emissions' is by far the most significant. This is true for both the allocation of credits within each category and the final point’s allocations that result from use of weighting factors. 29 credits are available for energy and C02 emissions which, when weighted contributes 36.4% to the total available performance.
The right balance between air tightness and ventilation can certainly be struck without significant addition to building costs. Material choice however, can greatly influence a building's long-term air tightness. Sheet membrane air barriers coupled with sealants, for example, are more effective than sealants alone, counteracting the effects of buildings (particularly timber frame) drying out.
Housing designers can now benefit from Accredited Construction Details (ACDs), Enhanced Construction details (ECDs) and, in Scotland, the Scottish Ecological Design Association Guide for both warm and cold roof construction. Examples of wall/ceiling ACDs include a junction of ceiling level air barrier with masonry inner leaf and warm roof with room in the roof. Accredited detail Sheet MCI RE 02, for example, shows a warm roof detail at the eaves in a non-habitable loft using Klober Permo forte vapor permeable underlay and appropriate tapes (with an alternative pre-taped option).
For non-residential construction, air tightness is just as important, despite the absence of any CSH equivalent. Roofing materials such as zinc, for example, require airtight construction if the metal's underside is unventilated. At the recently build Abergwynfi primary school near Neath, built to achieve a BREEAM 'Excellent' rating, zinc was used on a series of circular roofs. A Klober Wallint air barrier was installed with sealing tape to meet the specified air tightness performance.
With current Building Regulation requirements stipulating air tightness of only 7m3/hr per m2 compared with CSH 3 at 3m3, techniques used to achieve it must undoubtedly change. CPD presentations and literature on the subject are to be welcomed. 'The Code for sustainable Homes and air tightness in roofs' is a CPD presentation from Klober examining how to 'build tight and ventilate right' within the realms of practical pitched roofing construction. Supported by ‘Taking control of air leakage' www.klober.co.uk/air tightness it is a welcome source of information on a subject for which information is otherwise lacking.
By David Arendell, MD of Klober
What happens if you get a poor rating? There is no legal penalty for getting a bad label for an existing house. From the perspective of a seller or landlord, the effect of such a label can be expected to be a degree of market disadvantage in a competitive property market. From the perspective of a householder, it creates an awareness of the ongoing running costs, comfort level and environmental impact associated with energy use in the property. There are a number of simple measures that should achieve a good energy rating. Any combination of a number of the measures out lined below should achieve a high B rating. However, to achieve an A BER, almost all of these must be incorporated into the design.
- Increase insulation in the walls/attic/ floors
- Install an airtight membrane covering the complete fabric of the house
- Install advanced energy efficient windows/doors with triple glazing.
- Include measures to achieve controlled, healthy ventilation (Heat Recovery Ventilation)
- Install highly efficient condensing boilers (Under the Building Regulations, from 31 March 2008 all oil and gas fired boilers installed as replacements in existing dwellings must meet a minimum seasonal efficiency of 86 percent, where practicable. These boilers are frequently referred to as condensing boilers because of their operation)
- Insulate the hot water cylinder and all pipe work
- Install modern heating controls (zoned thermostat controls)
- Install certain types of renewable energy heating systems (Solar, biomass, geothermal)
- Specify 100 percent CFL bulbs in your design. When there is 100 per cent CFL bulbs specified, there should be a IO kWh/m2/yr change in figures when calculating the BER. This could potentially improve your rating. These bulbs cost from €5-€8 each and can also save you up to €250 per year on electricity.
- Maximize passive solar design. Passive solar orientated houses are designed to let heat into the building during the winter months and block out the sun during hot summer days. This can be achieved using deciduous trees or bushes to the south of the buildings.
NEW energy performance certificates will be compulsory as part of buying a house and architect, Paul McAlister gives his advice and answers your questions. "As an architect I have noticed clients' growing concerns regarding their buildings' energy efficiency. The primary motivation for these concerns are, a wish to preserve our environment, to combat reliance on fossil fuels and decrease our carbon footprints." On the other hand, when presented with the seemingly exponential rise in fuel bills, energy efficiency becomes more than just an abstract idea." In line with these growing concerns, the introduction of compulsory energy performance certificates (EPC's) in Northern Ireland completes the obligation placed by an ED directive on all member states to help improve efficiency.
What are Energy Performance Certificates?
The EPC is similar to the certificates which are currently supplied with household appliances such as refrigerators. It provides each building with two ratings from A (very efficient) to G (very inefficient). The first is based on the performance of the building and its services (i.e. heating and lighting) while the second assesses the building's environmental impact in terms of its carbon dioxide (C 0 2 ) emissions. The certificate also provides a list of recommendations on how to improve your building's rating tailored to its size, age and location.
Why do I need an EPC?
Energy performance certificates will be a legal requirement for anyone wishing to build, sell or rent a property. Also, the certificate is designed to make it much easier to compare the efficiency of different buildings. High efficiency translates into low running costs so if your property achieves a good rating, this will become a unique selling point, making it much more attractive to potential buyers. The penalty for failing to make an EPC available can be anywhere in the region of £500 - £5,000, depending on the value of the property:
When do they come into effect?
EPC's will be compulsory for all house sales in Northern Ireland from the end of June. They will be required for all new constructions from the end of September and all rentals and non-domestic property sales by the end of the year.
How do I improve my rating?
One of the most effective means of reducing your growing utility bills is to replace old boilers with new, more efficient ones this can cut heating costs by some 40 per cent. Fitting double or triple glazing can effectively reduce heat loss while cutting down outside noise levels. Fitting insulation or lagging to hot water pipes and tanks, insulating loft spaces, filling gaps in floorboards and insulating any unfilled cavity walls can all contribute to dramatically improving your efficiency and therefore increasing your EPC rating. It will not be possible to achieve an A rated home without employing various sustainable technologies such as rainwater harvesting and solar water heating.
An architect will be able to provide you with advice on how to build your home to achieve an A-B rating.
Paul is the founder of Paul McAlister Architects based in a converted Barn near Portadown. The practice has vast experience in designing bespoke homes, developments, renovation projects, and energy conscious design. You can contact the practice by email at email@example.com.