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.
Anyone familiar with spending a hot summer's day in a caravan and then another in a stone house with closed shutters will appreciate the meaning of ‘Decrement delay’. The inside of the caravan closely maps the rise and fall in external temperature to provide the familiar stifling effect on the occupants .
If you live in the South (southern USA) and already own solar panels, it could take you just under three years to make up the cost of the $3,000 Tesla Powerwall battery.
Total primary energy consumed from direct and indirect processes associated with a product or service within the boundaries of cradle to gate. This includes all activities from material extraction (quarrying / mining / harvesting), manufacturing, transportation and fabrication until the product is ready to leave the final factory gate.
Solar energy is a seriously underrated resource. More power from the sun hits the Earth in a single hour than humanity uses in an entire year, yet solar only provided 0.39% of the energy used in the US last year.
“As debate ramps up in Ireland about whether local authorities in Dublin should adopt the passive house standard, and the UK government scraps its plans for zero carbon homes, Dr Shane Colclough urges passive house advocates to prepare for the lobbying battles ahead by remembering the basic science behind the standard.”
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 importance of good ventilation in classrooms has been recognised since Victorian times, but many of today's schools fail to reach even basic levels of indoor air quality. Ewen Rose reports on a growing health crisis.
The Larixhaus is the first pre-fabricated straw bale passive house on the Iberian Peninsula. A project that took 7 months from start to finish, this single family home is located in the town of Collsuspina, Catalonia, Spain. Through careful bio-c1imatic design, thermal insulation with straw, an airtight envelope and high-performance windows, the Larixhaus has a projected space heating demand (calculated with PHPP) of 15kWh/m2 .a, approximately 80% less than that required by current Spanish building regulations. The project is a modest, but inspiring example of deep-green energy efficient construction, in preparation for the EU's 2020 deadline, when all newly built homes will need to be 'nearly zero energy'. Oliver Styles reports...
He huffed and he puffed...
Jordi, Itziar and their two daughters live in a small town in the hills above Barcelona, between rolling pine forests and burnt sienna escarpments. Renowned for its cool winters and even colder traditional stone houses, the area has been witness to one of the greener construction projects to have taken place in recent years south of the Pyrenees: the Larixhaus, Spain's first prefabricated straw bale and timber passive house. As straw bale building gains momentum in central Europe, with ground- breaking work from ModCell, White Design, LILAC and the University of Bath, the Larixhaus is a modest but determined example that timber and straw bale construction can move beyond the pigeon-hole of one-off self-builds and contend in the mainstream of beautiful, low-impact, energy efficient architecture. A simple, compact home which, despite the huffing and puffing of the big bad wolf, is set to brave the elements of this Mediterranean mountain region and place nearly zero energy construction on the map in preparation for the EU's 2020 deadline.
Early design: where the first steps count
The client's priority, from the outset, was to bring together a group of professionals with experience in timber and straw bale Passivhaus construction, who could design and build a small home at reasonable cost, where natural, renewable materials were married with a high level of energy efficiency and indoor comfort. In the early design stage, a simple and relatively compact building form was chosen, with 339m2 of thermal envelope enclosing a gross exterior volume of 437m3 over two floors, for a form factor of 0.78. The longest dimension of the building was aligned east-west, to provide maximum day lighting and reduce artificial lighting loads, resulting in a building aspect ratio of 1:1.3.
A location specific climate file was generated with the Meteonorm software and compared with the last 10 years of data from a weather station located 6km from the site, showing good agreement. Shading from nearby mountains was taken into account using a topographical horizon profile. The climate data was then entered into the PassivHaus Planning Package (PHPP) energy simulation and certification tool, for early stage design modelling and analysis.
Contrary to the orientation of all other homes of the street, the building's southern and most highly glazed facade was orientated perfectly south. PHPP modelling provided the required surface area of southern openings to take advantage of free solar heat gains in the winter. A combination of design strategies were modelled and tested for maintaining summer comfort with no active cooling.
To enjoy the spectacular views west to the jagged rock formations of Montserrat and east to the Montseny mountains, bedrooms are located on the ground floor, with a diaphanous kitchen, dining and living room space on the first floor. Wet rooms (bathroom and kitchen) are located in the same vertical plane, to reduce pipe runs and minimise heat losses in the domestic hot water system. To provide full fresh-air ventilation with minimal heat losses in the winter, a whole house ducted heat recovery ventilation system was chosen: careful early planning of duct routing made sure the duct lengths were kept to a minimum, reducing cost and energy losses. Operable windows on the east, north and western facades provide natural ventilation in the summer and sufficient natural light in all habitable rooms.
The skin: timber and straw bale
The timber superstructure and external cladding is PEFC certified, and was laser cut to order and delivered to the Farhaus workshop for prefabrication, 1 5km from site. The straw bales are 1200 mm x 700 mm x 400 mm, positioned vertically in the timber frame structure. The bales were sourced 1 25km away on the Costa Brava. The bales are enclosed on the outside with wood fibre breather board, followed by a 35mm ventilated gap and larch rain-screen cladding, fixed on timber battens. The ventilated wall reduces transmission heat gains in the summer and provides an exit for water vapour in the building structure - an important design consideration to avoid interstitial moisture build-up and condensation damage in straw bale construction. On the inside, the bales are shut in with 22mm formaldehyde-free OSB that acts as the air tight layer. Finally, Fermacell gypsum fibre board, over a service void, provides a dry-lined internal finish. Structural timber that spans the thermal envelope is thermally broken with cork insulation.
Two straw bale roof cassettes, with the bales positioned in the same direction as the walls, provide a thermally efficient roofing system, finished with clay tiles over a ventilated air gap, reducing transmission heat gains and summer overheating. Gravel infill on the intermediate floor adds some thermal inertia, although with the air-tightness and thermal insulation specification, combined with careful design of openings with external blinds, the building's thermal mass (calculated as 84Wh/K for every m2 of Treated Floor Area) was calculated as sufficient for maintaining summer comfort with natural ventilation. Given the site's altitude at 888m, peak summer temperatures are lower than coastal Mediterranean regions, averaging only 20°C in July and August. PH PP modelling showed that with no active cooling and a combination of glazing with a solar factor of 47%, external blinds on southern openings, and natural night ventilation, summer overheating frequency (when the indoor air temperature exceeds 25°C) could be kept below 3%, equivalent to a total of 36 hours in which the indoor ambient temperature rises above 25°C.
Despite not meeting the environmental criteria established between the client and design team, the most cost effective and thermally efficient solution for the floor slab was found to be 130mm of rigid polystyrene under the slab with perimeter insulation of 60mm around the edge of the slab.
The testing of alternative design strategies with PH PP modelling showed that an acceptable balance of heat gains and losses was achieved with triple glazing (with two low-e coatings, argon gas filling and TGI warm spacers), for a centre-pane U-value of 0.65W/m2.K and solar factor of 47%. Soft-wood Farhaus frames provide a U-value = 1.00W/m2.K, with cork insulation to reduce installation thermal bridges. The average installed window U-value is 1.06W/m2.K, not enough for cold' central European climates but sufficient in the Collsuspina climate to meet the comfort and hygiene requirements set by the Passivhaus standard.
The average weighted thermal transmittance of the building envelope is U-value = 0.21 1 W Im2K. The door blower test gave an impressive result of n50 = 0.32ACH (air changes per hour). Cold bridges were eliminated or reduced with modelling and optimisation in the design phase.
The building shell was prefabricated in the Farhaus workshop over a period of 6 weeks. It was divided into 10 separate modules, with the air tight layer and window frames installed and sealed. The modules were transported to site and the basic structure was assembled in two days. Pre-fabrication minimises on-site construction times, providing cost savings and near-zero on-site waste. The Larixhaus' embodied energy and C02 emissions derived from materials are minimised by prioritising natural, non-toxic, renewable materials with minimum processing (certified timber, locally sourced straw, cork, and gypsum fibre board).
Indoor air quality, acoustic comfort and active systems
Healthy indoor air quality is achieved through the use of non-toxic, Iow-VOC, natural materials. Exposed timber inside the home is either untreated or coated with water-based varnish. Healthy materials are combined with whole house ducted heat recovery ventilation to provide efficient, comfortable full fresh air ventilation during the winter. Cool air is brought into the home and pre-heated by outgoing stale air through a Passsivhaus Institut certified Zehnder Comfoair 350 ventilation unit, with an installed sensible heat recovery rate of 79%. PHPP simulations showed an average seasonal COP of 9. Efficient DC fan motors are essential for reducing electricity consumption: calculations showed that, given an average of 4,700 hours of operation per annum, at an air change rate of 0.40 (91 m3/h), the unit will consume only £31 of Spanish electricity each year (where household electricity is the 3rd most expensive in Europe). The ventilation unit is fixed on acoustically insulated mounts and located in the service cupboard by the entrance on the ground floor. Silencers on the indoor air supply and return ducts, combined with adequate duct sizing to control air velocities, means the system has a maximum measured sound pressure level of 33dB(A) in living spaces. The result is a quiet, discrete and efficient comfort ventilation system.
The near-zero heating demand is met by two low-cost 500W wall-mounted electric radiators in each bedroom, and one 450 W electric towel radiator in the bathroom. On the first floor, a 4kW air-tight log stove (that modulates down to 2kW) with a twin-walled concentric chimney flue, provides heat on very cold days, without compromising air tightness. Hot tap water is produced by a compact air-source heat pump unit with a COP of 3.75 (@ air = 15°C and water = 45°C) and a heat store of 300 litres. The air intake of the heat pump is located just above the stale air outlet of the ventilation unit, providing some performance improvement. The clients have set timing controls on the heat pump to make sure it does not activate between 1 1 pm and 8am in the winter, to avoid poor 'performance when outdoor air temperatures are low. Following 3 months of use, there has been sufficient hot water to meet daily demand with this control strategy.
Cooking is done on an induction ceramic cooktop with a re-circulation cooker hood. Artificial lighting is with LEDs and all white goods are A++. If the Spanish government decides, at some point in the future, to reverse the current legislation and encourage the use of renewable energy technologies rather than bending to the pressure of the large energy companies, the clients intend to install a grid-tied photovoltaic array to achieve a net zero energy balance. When the budgets allows, a rain water catchment system will follow suit (pre-installation was done during construction) .
Beyond PHPP and into the real world
A remote monitoring system will be installed in the coming months, providing quantitative data over a 2-year period, monitoring outdoor temperature and humidity, indoor temperature, humidity and C02 levels, together with electrical energy consumption for space heating, ventilation, hot tap water, lighting and equipment. It will be particularly interesting to see the in-use summer performance of the building.
Meanwhile, feedback to date from the clients shows that with outdoor night time temperatures reaching -1°C, indoor temperatures have remained above 20°C with no active heating, as long as there is some sun during the day. For successive days with no sun, they turn on the electric radiators for half an hour at night and in the morning, to maintain comfort. The first test of the log stove ended with Itziar opening the windows as it got too hot in the sitting room (!), confirming the PHPP calculated peak heating load requirement of 11 W 1m2. At least during this first mild winter, the stove seems largely redundant. The specific construction cost of the build has come in at around £1,005/m2, an estimated 14% more costly than building to current regulations in Spain. This gives an approximate simple payback time of just under 9 years, for a building with an expected useful life of 80 years.
So goes the story of the Larixhaus: a green-building homage to Catalonia and its rich history, number 10 in a growing list of healthy, comfortable, Passivhaus constructions south of the Pyrenees.
Client: Jordi Vinade, Itziar Pages
Architecture: Nacho Mart, Maria Molins, Oriol Mart.
Passivhaus design, PHPP analysis, M&E: Oliver Style, Vicenc Fulcara - ProGETIC SCP
Contractor: Albert Fargas - FARHAUS
5tructural Engineering: Manuel Garcfa Barbero - Klimark Architectural Consultant: Valentina Maini
Energy standard: PassivHaus new build Location: ColIsuspina, Barcelona, Spain Treated floor area (PHPP): 92m2 Construction type: timber construction Completion date: December 2013 Completion time: 7 months
Space heating demand (PHPP): 15kWh/(m2a) 5pace cooling demand (PHPP): 3.2kWh/(m2a) Heating load (PHPP): 11W/m2
Cooling load (PHPP): 3.9W/m2
Primary energy requirement (PHPP): 96 kWh/(m2a) Construction costs (gross) [1m2]: 1211/m2
Air tightness (n50): 0.32ACH
Exterior wall: U-value: 0.127 W/m2.K: in> out
- 13mm plasterboard (Fermacell)
- 35mm service void between timber battens at 8%
- 22mm 05B 4 [air-tight layer]
- 400mm straw bale insulation  between timber joists at 8%. thermally broken with cork insulation 
- 16mm wood fibre breather board (DFP Kronolux) Wind tight membrane and ventilated larch rain screen cladding, flxed on external timber battens
Floor slab: U-value: 0.165 W/m2.K: bottom> top
- 130mm XP5 insulation 
- 350mm reinforced concrete floor slab
- 80mm Pavaflex wood fibre insulation  between timber joists at 10 %
- 22mm timber flooring
- 60mm XP5 insulation  around the edge of the floor slab
Roof: U-value: 0.122W/m2.K: bottom> top
- 15mm timber board (Fir) 22mm 05B 4 [air-tight layer]
- 400mm straw bale insulation  between timber joists at 2% 16mm wood fibre breather board (DFP Kronolux)
- Timber battens and roof tiles
Windows / doors
- Farhaus, Fargas window frames
- 50ft-wood laminated wooden window frames (90mm)
Uframe = 1.00W/m2.K
Average U- value window = 1.06W/m2.K
- Triple glazing. with two low-e coatings and argon gas fllling; 33.2/16argon/4/16argon/4; TGI warm spacer
U-value glazing = 0.65W/m2.K
g-value = 47%
Entrance door - Farhaus: Fargas door
- Triple glazed entrance door with identical speciflcation as windows
Udoor = 1.00 W/m2.K
- Zehnder ComfoAir 350 Luxe
- PHI certifled ducted whole house mechanical ventilation with sensible heat recovery
- Distribution in HDPE 90mm pipes
- Ground floor: electric radiators
- First floor: Rika Passiv blomass stove
Domestic hot water system
- Theodoor Aerotermo 300 Plus
- 3.6kW thermal compact air source heat pump unit, with backup electric immersion heater.
Oliver is a certified PassivHaus designer/energy consultant and co-founder of ProGETIC, an engineering practice based in Barcelona, Spain. He specialises in passive design and building performance optimisation through energy modelling. He has an MsC with distinction in architecture, with the Centre of Alternative Technology and University of East London. He enjoys working closely with designers, developers, engineers and free thinkers who want to build or renovate beautiful, healthy, comfortable buildings with low running costs. - OSTYLE@PROGETIC.COM
Style, O. (2014) ‘Homage to Catalonia: A pre-fab straw bale passive house 'first' for the region’, Green Building Magazine, vol. 23, Spring 2014, pp. 20-24.
Zero carbon is great as a political aspiration but will it stack up effectively as a policy? Richard Hillyard examines Government aims to impose zero carbon targets on the construction industry. Back in July 2007 the Government published the Building a Greener Future statement. This policy document announced that all new build homes would be zero carbon from 2016.
The definition of zero carbon requires new dwellings to take into account:
- emissions from space heating, ventilation, hot water and fixed lighting,
- exports and imports from the development (and directly connected energy installations) to and from centralised energy networks.
Note:- Expected energy use from appliances is excluded from zero carbon definition.
By following this policy the Government expects new buildings to have net zero carbon emissions over the course of a year.
The definition of zero carbon consultation subsequently introduced by the government, sought views on the Government's proposals. This consultation ran from 17 December 2008 to 18 March 2009 and goes on to explain how to achieve net zero carbon emissions.
The Government also announced that from 2019 all non-domestic new builds will also be required to have zero net carbon emissions, with earlier dates for schools (2016) and public sector buildings (2018).
Wisely, the government set boundaries to what it meant by zero carbon. The embodied energy content of construction materials is not covered, and neither is the transportation of materials. Additionally, transport emissions associated with developments are not included as the government intends to deal with these through other policy instruments.
Given these omissions, it could be argued that Government's proposals do not equate to zero carbon. Even if it is not possible (nor cost-effective) to construct a building without generating any greenhouse gases, how far could we get by dramatically improving the efficiency and sustainability of construction methods?
In any case, does it really matter? Less than one per cent of the UK's existing building stock is replaced every year, and it's been estimated by the Department for Communities and Local Government (CLG) that 87 percent of the current housing stock will still be around in 2050. That means that the UK cannot meet its carbon reduction targets without a far-reaching retrofit programme for existing buildings.
The UK Green Building Council's proposal for a Code for Sustainable Buildings will play an important role in improving the focus on energy efficiency in existing buildings. But this is just one of a hierarchy of measures that the Government says will be needed.
The consultation document proposes a three-stage hierarchy for designers to achieve zero-carbon. The first step for energy efficiency requires compliance with Part L of the Building Regulations. This stage may also encompass other regulatory instruments, such as a mandatory requirement to design to Level 6 of the Code for Sustainable Homes.
The second stage proposed by Government is something called Carbon Compliance', which essentially is the use of on-site micro-energy generation. A report by the UK GBC Zero Carbon Definition Task Group believe over 80 per cent of homes in the UK to be unable to achieve zero carbon targets this way. The development of near-site and off-site low and zero-carbon energy generation is also being proposed.
Initially there were reservations over whether the use of biomass technologies could be included in the zero carbon strategy. However, the government appears to be in full support of using biomass systems both within new homes and as a source of direct heat from nearby off-site generation.
The third stage in the zero-carbon strategy is what is known as allowable solutions', which is a buy-out fund or form of carbon offsetting through high quality international investment in low and zero carbon projects.
This third way will, it is believed, only be permitted where energy efficiency and carbon compliance are unable to be achieved totally through on-site and near-site measures achieve the goal of zero carbon - in other words the residual emissions.
The government is proposing a system of credits to permit off-setting to occur. Credits will be awarded to developments that have a range of energy-saving criteria. For example, energy-saving appliances and low and zero-carbon technology capable of exporting energy to the grid will earn credits to enable an offset of residual carbon emissions.
The government would prefer off-site low and zero carbon technologies to be included in this part of the hierarchy by feeding into the national grid.
So will the policy work? The first two parts of the hierarchy - energy efficiency and carbon compliance - are signs of forward thinking. With a few tweaks, off-site low and zero carbon energy generation could play an integral part of reaching the zero carbon target, but only if the contribution from the grid can be guaranteed to be clean.
Other questions remain to be answered. For example, with allowable solutions, will off-setting contribute to reducing carbon dioxide emissions enough for claims of zero carbon to stack up - not just initially but over a sustained period? Or is it, as some might argue, just a way of covering up holes in the system, and easing collective guilt?
Off-site low and zero carbon energy generation technologies sounds like reasonable measures, but if they are supplying to the grid as opposed to supplying directly to a development, what guarantees will there be that this clean energy will not be lost in the overall electricity generation? This is a key issue, especially when it's mixed with the output from the proposed eight new coal power stations (each potentially generating eight million tonnes of CO2 per year) that the Government is keen to build.
These questions highlight the credibility gaps that still exist between intention and delivery in Government's push for a low carbon and sustainable energy future. Whatever transpires following the zero-carbon consultation, tackling the issue effectively will not only significantly affect the environment, but also our pockets.
Zero carbon targets on the construction industry, [Online], Available: http://www.bsria.co.uk/news/article/clean-home/ [18 March 2014].
To help stimulate the uptake of renewable technologies in Northern Ireland, Northern Ireland Electricity (NIE) will provide support for wind and solar photovoltaics (PV) following the closure of the Low Carbon Buildings Programme Stream 1 grant for renewable electricity technologies in early February 2010. The following grants are available from the NIE SMART programme which is managed by NIE Energy on behalf of NIE:
|Photovoltaics||£2,000 per kWp or 30% of the relevant eligible costs, whichever is the lesser amount (Max. £10,000)|
|Wind||£900 per kWp or 30% of the relevant eligible costs, whichever is the lesser amount (Max. £4,500)|
Funding will not be available for retrospective installations – only applications submitted from the 8th March 2010 will be eligible for funding from this new grant (PV applications submitted from 19th July 2010 will be eligible for the increased grant levels).
The guidelines for support are available below:
- NIE Household Grant guidelines
- Microgeneration Certification Scheme installers
- Microgeneration Certification Scheme approved products
Please note that NIE does not guarantee or underwrite the performance of any technology and it is your responsibility to ask accredited installers (or the manufacturer) what reassurances they can provide in terms of the expected performance of the system.
Clarification on the position of MCS products which are in transition NIE Energy will consider applications from customers who are using an accredited MCS installer (whose details are listed on the MCS website) and an accredited product (even if it is just noted on the MCS website as being in ‘transition’). We have had confirmation from MCS that products which are in ‘transition’ are at some stage in the MCS certification process but we must advise customers and installers that we will be checking each application with MCS to make sure that the manufacturer of the product is actively engaged in the certification process with MCS. Applications may be refused if, after checking with MCS, it is discovered that a manufacturer is not actively pursuing the MCS certification.
It is your responsibility to check with your local authority about whether or not planning permission is required. Please note that you must have received confirmation about planning permission before submitting an application for grant funding from NIE. If you proceed without planning permission then your application will be invalid and you will not be able to claim a grant.
Please note that farmers who are on a domestic tariff with NIE Energy will be eligible to apply for the grant but farmers who are on a business tariff are not eligible.
Please download an application form here and fill it in carefully – you must sign the application form as your agreement to the terms and conditions of the grant. Link Below.
Please send your completed application form and a copy of your 2 quotes to:
Delta Hamilton NIE Energy Woodchester House 50 Newforge Lane Belfast BT9 5NW
Then please don’t start work until you have had confirmation from NIE Energy that your application has been successful.
If your application is accepted then you will then receive a grant offer letter – households who proceed with the work without having applied and received a NIE grant offer letter will not receive a grant. There will be no exceptions to this requirement.
This new NIE Household Grant is a limited offer and is available only on a ‘first come, first served’ basis. Some installations will be profiled to raise awareness of the uptake of renewable energy in Northern Ireland.
All grant administration is managed by NIE Energy so if you require any further information about the grant please contact Delta Hamilton by emailing Delta.Hamilton@nieenergy.co.uk.
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
If you are a householder in Northern Ireland interested in generating your own heat or electricity, you can apply for a renewable technology grant of up to £2,500 per property. The Low Carbon Buildings Programme incentivises householders interested in fitting their own green energy systems, such as solar photovoltaic’s, wind turbines, small hydro, solar thermal water, ground source heat pumps and Bio energy, by providing grants to contribute towards the cost of installation.
The Programme is funded by the Department of Energy and Climate Change and managed by the Energy Saving Trust. Many people claim that they want to do their bit to help tackle climate change but are put off by the costs associated with renewable technology. By taking advantage of the grants available through the Low Carbon Buildings Programme, homeowners will find small renewable technologies a more affordable option. By installing micro generation technologies, homeowners will not only play a vital role in tackling climate change but will also save themselves money in the long run.
Noel Williams, Head of the Energy Saving Trust Northern Ireland commented: "I am pleased that householders in Northern Ireland have already applied for grants to install green energy technologies through the Low Carbon Buildings Programme and hope that even more people will follow in their footsteps and reduce their carbon footprint."
To be eligible for a grant through the Low Carbon Buildings Programme, consumers must choose a certified product and have it installed by a certified installer.