Design and planning principles
Basic principles of Passive House building services The spatial arrangement of building services systems, such as the location of plant rooms and the layout of vertical and horizontal distribution systems, is primarily the architect‘s task. The spatial integration of building services requires the development of a system similar to that of the construction or the internal circulation of the building. The actual technical design, on the other hand, should be prepared by specialist planners.
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load-bearing structure thermal envelope plant room, shafts and ducts air supply ducts
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transfer zone extract zone supply air zone enoz refsnart enoz ria ylppus enoz tcartxe 4.22
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Location of the plant rooms within or close to the thermal envelope The location of the building services is closely related to the principle of the thermal envelope. A general decision has to be made as to whether the technical systems (e.g. mechanical ventilation unit, heat generator, cooling system) are to be placed inside or outside the building envelope. In a Passive House, it makes sense to install the technical equipment inside the thermal envelope, for example in an insulated basement room (fig. 4.21 and 4.24): • The airtightness concept is fairly simple because only a few penetrations need to be made airtight, such as those for the services connections, the fresh air and waste air ducts and possibly brine pipes. Complicated penetrations for cables can also be avoided. • The heat loss through heat generation, storage and distribution is much lower when the heating system is placed inside the thermal envelope. • If the plant room is located close to a vertical shaft the lengths of the horizontal runs can be reduced considerably. If the conditions above cannot be met, the plant room should at least be positioned close to openings in a vertical shaft in order to minimise the lengths of horizontal runs outside the thermal envelope. Plant rooms that are not inside the thermal envelope can either be placed in the basement, next to the building as a kind of extension or on the roof as a superstructure. Principle of short runs In Passive House buildings, it is usually not necessary to place radiators beneath windows. The ventilation valves do also not necessarily have to be fitted close to the facade. As a consequence, all vertical and horizontal distribution runs for the heating and ventilation units can be
placed in the core of the building. The short runs of the distribution lines and ducts resulting from this arrangement are beneficial not only with regard to costs and space but also energy loss and the requirement for auxiliary power. Because the PHPP does not allow default values for pipe runs and heat loss through distribution, these potentials for improvement are easily perceived in the energy balance. This is a fairly significant aspect of the Passive House standard. If this were not the case, the high energy efficiency of the thermal envelope and the primary building services would be hampered by the secondary services involving the supply of heat, i.e. storage, distribution and transfer. Air zones Initially, the separation of the building into air zones is a sorting procedure which is very much dependent on the user and the layout of space: • All rooms that require a direct supply of fresh air are assigned to the supply air zone. In a residential building, these should include all living and dining rooms, recreation space and bedrooms. • The extract zone includes all rooms where there is a need to remove moisture and smells, such as kitchens, bathrooms, toilets, shower and utility rooms. • The intermediate or transfer zones are the areas or rooms through which the air is drawn, i.e. between the supply air zone and the extract zone. There are no special requirements for these rooms. The air flow is achieved through transfer paths, such as gaps beneath doors, at the door head or through overflow valves. The aim is to ensure an even supply of fresh air throughout all rooms and at the same time remove smells and moisture close to where they occur most. The layout of air zones forms the basis for designing the air duct system (fig. 4.22). Cascade ventilation system The ventilation concepts tried and tested in Passive House buildings have become simpler and more low-tech in recent years. Supply air is now, for example, only supplied to individual rooms and bedrooms, whereas the living and dining rooms are considered as extended transfer zones. As a consequence, it has been possible to reduce the duct runs, the air volume and the power consumed by fans without changing the indoor air quality. However,