Single-storey and two-storey houses may have the same floor area but very different ventilation networks. In one, long horizontal routes are the main issue; in the other, the position of vertical routes and the link between floors matter most. A heat-recovery unit therefore cannot be selected from square metres alone while treating duct layout as secondary. This article compares planning tasks; it does not claim that either house type is inherently cheaper or better ventilated.
The starting point is the same: rooms and demand
In both cases, prepare a room list, plan supply and extract ventilation and assess use. Bedroom numbers, occupants and wet areas can differ even in houses of the same size. You also need to know future changes: a study, an additional bedroom or a second bathroom. Initial floor area cannot replace the full picture of use.
The Zehnder systems overview shows how equipment and solutions are matched to different buildings. The practical conclusion is simple: a general equipment type does not describe a particular network's geometry. The designer needs a plan with actual heights, structures and equipment space. Lengths and bends added later must be reviewed, not treated as an insignificant installation detail.
Horizontal routes in a single-storey house
A low, spread-out layout may have rooms quite far from the plant room. This encourages early consideration of a central distribution location or sensible routes. However, a shorter route cannot be planned without regard for beams, doors and airtightness layers. Compare several options before finally approving plant-room and corridor finishes.
If much of the network is in the loft, assess its temperature environment and access. An unheated space is not automatically a convenient location for every product. Insulation, joints and condensation prevention must be designed for the situation. Owners need to know how parts requiring inspection or cleaning will be accessed.
Vertical connections in a two-storey house
Plan a vertical route early, coordinating it with structures and other systems. It has an actual cross-section, fixings and necessary penetration details. A line beside the stairs on a drawing does not mean that everything will fit. If an opening passes through a floor structure, agree the solution with the relevant specialists.
A riser position may shorten routes on one floor but create long detours on the other if poorly located. Review both levels simultaneously. Do not treat the ground floor as finished and leave only a random remaining void for the upper floor. Coordinate the network as one system.
The equipment position changes more than length
A heat-recovery unit needs servicing space, external connections, electricity and other conditions specified for the model. A central location is not always best if it places the unit beside a bedroom wall or in a hard-to-reach corner. Assess selection alongside noise and ease of use. An attractive recess must not prevent filter removal.
In a two-storey house, consider who will have to reach the equipment and how parts will be carried out. If servicing requires difficult climbing or removal of finishes, the location may be poor even with short routes. A similar problem occurs in a single-storey house when equipment is hidden behind store-room furniture. Access must be real, not theoretical.
Resistance and balancing
Longer routes, bends and distribution components change network operation. A long branch on one floor cannot be compared with a short branch on another solely by their identical duct diameter. Design airflow must be achieved at the particular point and measured appropriately. The equipment percentage on a screen does not replace measurement of a room's airflow.
The EPA renovation guidelines treat whole-home ventilation as a system that can be verified. This principle should not become a reason to copy foreign regulatory figures into Lithuanian projects. Your designer sets the specific design parameters, and acceptance results must relate to actual measurements and operating mode.
The air path between rooms
In both house types, consider how air moves from supply rooms to extract locations. Internal doors, partitions and their gaps may change the result. A large stairwell opening must not be treated as a substitute for air transfer from every room. If bedroom doors are closed, account for their position in the design and test.
Consider different night-time uses too. People may sleep on one floor while active use continues on another. The control arrangement must be understandable to the owner and deliver the required airflow without unnecessary noise. Having different floors does not in itself mean two separate systems are essential, but that option can be assessed against the actual task.
Sound transmission
Noise may travel from equipment, through ducts and via structures. In a two-storey house, the link between upstairs and downstairs rooms matters; in a single-storey house, the link between adjacent bedrooms. One silencer beside the unit does not prove that every path is addressed. Acoustic arrangements must suit the network layout and airflows.
Owners should ask for a demonstration at the normal night-time setting, not just the lowest speed while the house is empty. Also distinguish the equipment's declared sound rating from actual sound in the room. They have different measurement conditions. Acceptance should cover the actual arrangement, not just the product catalogue sheet.
The as-built layout after the work
If the riser position or branches change during installation, update the plans for every floor. Photographs with fixed reference points will help future repairs. Owners need to know the actual routes so they do not damage a concealed system when fitting furniture or changing finishes later.
What should be provided for design?
Prepare plans for all floors, sections, room uses, structural information and a possible equipment location. Mark which finishes are already complete and what you do not want changed. The airflow guide explains general selection, while an enquiry allows discussion of the particular house.
A suitable solution must be compared in terms of the entire installation and maintenance. A shorter route does not always mean lower overall risk or better acoustics. The difference between single-storey and two-storey houses is a planning task best resolved before structures are closed, not merely by searching for spare space during installation.
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