The Passive House Institute ( PHI) was founded in 1996 by the concept's co- creator Professor Wolfgang Feist. Based in Darmstadt, Germany, the institute have developed the Passive House Standard through extensive research and monitoring of thousands of Passive House projects. The success of the Passive House Standard in Europe has been, in part, due to the expert guidance and certification schemes lead by the PHI, and also thanks to the backing of the EU and respected professional institutions that have embraced the Standard. European projects such as CEPHEUS ( Cost Efficient Passive Houses as European Standards) and PEP ( Promotion of European Passive Houses) have been launched to assess the potential of the Passive House Standard with regard to providing affordable, low energy homes as standard across Europe. These projects have been very successful and have played a large role in the development and progression of the Passive House Standard. Passive House Design A building designed to Passive House Standards will provide a number of benefits for its owners andor tenants. Such benefits will include excellent indoor air quality with reduced internal pollutants and a constant supply of fresh air, a reduction in maintenance and running costs as well as a drastic reduction in energy consumption and CO ² emissions. Passive House Criteria and the Passive House Planning Package ( PHPP) The basic principles upon which the Passive House Standard has been developed centre around a set of strict criteria that every Passive House project must adhere to in order to become a certified Passive House. The main criteria are as follows: . Space heating demand = 15 kWh/( m ² a) . Building heating load = 10 W/ m ² . Useful cooling demand = 15kWh/( m ² a) . Primary energy demand = 120kWh/( m ² a) . Building air- tightness = 0.6 ac/ h  ¹ . Excess temperature frequency = 10% Compliance with these criteria is verified using the Passive House Planning Package ( PHPP) throughout the design and construction process. The PHPP is a sophisticated design tool specifically developed by the PHI for the accurate planning and calculation of Passive House buildings. The PHPP is similar to SAP, however PHPP is considerably more advanced with the ability to provide accurate results that have been proven through extensive monitoring of existing Passive House buildings across Europe. In addition to the PHPP calculations, there are a number of sub- criteria and design considerations to be taken into account when planning a Passive House Project that It is possible to build a Passive House to the same price as a house built to current Building Standards in the UK PASSIVEHOUSE ATMARCH- APRIL2010 15 Below: Passive House example from Steingaden, Germany ( South elevation)

are intended to make certification easier and more achievable. These are shown briefly in the Passive House diagram and will be discussed in more detail in part two of this article, Passive House: Technical Overview. Certification It is important to note from the outset that ' Passive House' ( and/ or ' Passivhaus' as it is in German) is not a legally protected concept, meaning that anyone can claim their building is a Passive House. However, the true proof of a building being a Passive House is certification by the PHI or an independently recognised representative of the PHI. Anything else is merely built ' towards' Passive House Standard, using Passive House products, or simply taking advantage of the Passive House reputation for quality and comfort. The intention to build a Passive House and seek certification must be established and agreed upon at the outset of a project. The process of planning and detailing a building to Passive House Standard demands consideration of the Passive House requirements at every stage of the design. Achieving a certified Passive House building after a project has been designed or after construction has begun can be extremely difficult, and in many cases impossible. It is therefore imperative that the decision to ' go passive' is clear from the beginning. Construction and Energy Costs Through the use of rigorous planning and precise execution of construction and site management, it is possible to build a Passive House to the same price as a house built to current building standards in the UK. Generally though, it is observed that a Passive House can cost from 8- 15% more than a conventional house. The additional costs come through the upgraded building envelope and the mechanical ventilation system. However, over the life cycle of the Passive House this increase in capital costs is eclipsed by the dramatic savings made due to reduced energy consumption and the almost non- existent heating bills. Improved thermal comfort levels are another of the major benefits to building a Passive House, together with the reduced energy costs and CO2 emissions. The reduction in the energy consumption of a Passive House leads to a situation where renewable technologies become a better and more economical option for a project. This is because they can now provide sufficient energy for the building's needs, in many cases create more energy than required, which can result in the house owner selling this energy back to the grid, for a profit. Passive Houses in the UK so far Passive House development is beginning to take shape in the UK with interest and knowledge increasing at a fast pace in recent years. The first UK Passive House projects were built in Wales in the form of a community centre and a detached family house ( Certification by the BRE). In November 2009, Scotland had its first certified Passive House project confirmed. The affordable housing project Tigh- Na- Cladach in Bethania, Dunoon was certified by the Scottish Passive House Centre having met the relevant criteria. Channel 4' s programme Grand Designshas been filming the development of England's first certified Passive House project. Although the programme will be aired in September of PASSIVEHOUSE 16 ATMARCH- APRIL2010 Left: Comparative values for CO2 and energy use per year for different types of houses. Universities and local government are interested in Passive House design, with local councils investigating the potential benefits