What is a Passive House?
With a PassivHaus or Passive House design, the core focus is reducing the requirement for space heating and cooling, thereby reducing the overall energy consumption (and associated running costs!), making the house more energy efficient or eco-friendly. The Passive House standard also sets out to provide good indoor air quality and thermal comfort. Whilst a PassivHaus home concentrates on passive design features such as insulation, airtightness, and solar orientation, it also allows certain active elements to be included – notably MVHR (Mechanical Ventilation with Heat Recovery).
The central design principle in a PassivHaus home is that it can maintain its internal temperature and air quality, simply, by using a small amount of heating or cooling to the air. The modified air (heated or cooled) is then circulated by the ventilation system. This may eliminate the need for a traditional central heating system and boiler. Although in practice, some sort of central heating is usually installed in our Irish climate.
Passive House design creates a building that provides high levels of thermal comfort all year round, using exacting standards in design and in its construction, meaning that common building faults are avoided. PassivHaus buildings are designed for long life and high performance and to achieve the Passive House Standard. The key requirement is that the energy needed for space heating must not exceed 15 kWh/m2/yr. The Passive House standard was developed in Germany by Professor Wolfgang Feist, as a ‘fabric 1st’ approach to minimize the energy requirements and running cost of a building. Passive House has become a world-renowned approach to creating sustainable design and construction.
The Passive House standard is not confined to houses; it can be used in apartments, office buildings, schools, supermarkets, extensions, and renovations. Passive house design is not an attachment or supplement to architectural design, but a design process that is integrated with architectural design.
What is the difference between Passive House and Zero Carbon?
Passive House is similar to the Zero Carbon building standard in Northern Ireland (NI), but it can't be compared directly. The PassivHaus Standard is measured in terms of absolute energy use for space heating only, whereas building regulations and Zero Carbon set standards according to reductions in carbon dioxide emissions for space heating, water heating, and lighting. With Passive House there are strict requirements and standards to meet in the wall (min U-value of 0.15 W/(m2K)) and triple glazed windows (min U-factor 0.8 W/(m2K)) and virtually eliminating all thermal bridging. In Zero Carbon design and construction, the standard of insulation can be offset with renewable energy sources (ie, Zero Carbon buildings can have a poor building fabric, but still be Zero Carbon if most of the heating & electricity required are from renewable energy sources).
Which is better - Passive House or Zero Carbon?
By concentrating on fabric-first measures to reduce energy consumption (thereby increasing energy efficiency), as per the Passive House Standard, you are concentrating on getting the basics right: your house will have low running costs, with or without add-ons, such as PV solar panels etc. Adding on the renewable energies will enable you to meet Zero Carbon standards as well as Passive House standards.
As Passive House Certified Architects in Northern Ireland (NI), we at Marshall McCann Architects firmly believe that designing to meet both Passive House and Zero Carbon Codes is easily achievable with only a small increase in build cost; the cost of which is offset by the saving in the running cost of the building - saving you money in the long term. And ultimately, the end-game of building an energy efficient house is to have a comfortable living environment, with little energy costs.