Table of Contents
Ventilation CAD & BIM models
In a typical Irish home, MVHR or MEV plant is small compared to structure and finishes. Nevertheless, poorly coordinated ventilation CAD layouts can still trigger some of the biggest delays on site. Late changes to beams, dropped ceilings or pipework zones quickly eat into programme, budget and goodwill.
When an architect or technician is actively involved in residential ventilation design, coordination becomes far simpler. At EcoVent, we work on the installation and commissioning side every day, so this guide is about sharing practical experience that plugs directly back into ventilation CAD and ventilation BIM models workflows. The aim is straightforward: layouts that are realistic for installers, easy to check in CAD, and dependable at handover.
Why model ventilation early in CAD and BIM
Ventilation is sometimes left to “the services contractor later”. However, from a ventilation CAD and ventilation BIM perspective, early modelling brings several advantages:
- MVHR and MEV units need a realistic plant space, with access for maintenance and a condensate route that actually works.
- Ducts, manifolds and silencers compete for the same zones as structure, plumbing and electrical services.
- Ceiling heights and bulkheads are easier to agree while the design is still flexible.
- The team can prove that the MVHR ductwork layout is buildable before tender, not during first-fix.
Even a simplified ventilation layout in CAD, with sensible clearances and standard duct sizes, will prevent most clashes.
Typical coordination problems with MVHR CAD in Irish homes
On real projects, the same MVHR coordination issues appear again and again:
- Ducts clashing with structure – main ducts running through beams, truss webs or steel flanges.
- No room for bends and silencers – straight lines drawn in CAD with no allowance for fittings, bends or acoustic treatment.
- Overloaded service zones – ventilation, wastes, heating pipework and cabling all stacked into a 100 mm ceiling void.
- Crowded plant cupboards – MVHR unit, manifold, pipework and electrics squeezed into a space that only fits the bare unit dimensions.
- Badly placed terminals – external grilles too close to flues, windows or neighbouring boundaries.
Most of these problems disappear when ventilation is treated as a primary service and modelled to a sensible level of detail (for example LOD 200–300) in Revit, Archicad or AutoCAD. When the architect leads this coordination, installers like Eco Vent spend far less time trying to “make it work somehow” on site.
A simple workflow for ventilation CAD coordination
The workflow below works for most ventilation CAD environments, whether the model lives in Revit, Archicad or AutoCAD. It also fits easily around existing structural and architectural processes.
1. Reserve service zones in the architectural model
Early in the design, it helps to:
- Define horizontal service zones (depth and location) in ceilings, floors or bulkheads for MVHR and MEV ducts.
- Add vertical riser zones in cupboards, shafts or discreet corners of rooms.
- Lock these zones into general arrangement drawings and coordinate them with structure and plumbing.
By doing this, ceiling height, bulkhead positions and joist penetrations are discussed once, on drawings, rather than repeatedly on site. EcoVent routinely uses these predefined zones to shape the MVHR ductwork layout so that installers are not fighting the structure.
2. Place a realistic MVHR or MEV unit family
Instead of a generic box, a real product family gives a much more reliable result in MVHR CAD:
- overall dimensions are correct
- spigot positions and sizes are accurate
- maintenance clearances are clearly shown
Manufacturers such as Duco and Domus Ventilation provide free BIM models for ventilation, including Revit and DWG files, that can be dropped straight into the model. This quickly answers simple but critical questions, such as whether a cupboard is deep enough to open the front panel and change filters.
3. Draw main duct routes first
From the MVHR or MEV unit, it is usually best to:
- Sketch main supply and extract trunks through the reserved service zones.
- Minimise sharp bends; aim for gentle sweeps and short routes where possible.
- Keep main ducts away from the most sensitive areas (bedrooms), or allow space for silencers.
Once the main trunks are positioned, branches can be added with much greater confidence. This is also the stage where EcoVent’s on-site experience is valuable, because we know which routes are practical for installers and which ones will cause access or acoustic headaches later.
4. Add branches, manifolds and valves
Next, the model can be refined:
- For radial systems, place manifolds in accessible locations and model flexible branches to valves.
- For rigid systems, draw branches to each room, respecting minimum bend radii and the physical space needed for fittings.
- Place supply and extract valves in logical positions in reflected ceiling plans, away from beams and fittings.
The goal is not to show every bracket. Instead, the intention is to produce a ventilation layout in CAD that clearly shows where space is genuinely needed and where clashes with structure or other services are likely.
5. Run clash detection and tidy the layout
With the main ventilation geometry in place, clash detection becomes meaningful:
- Check the ventilation BIM model against structural framing, plumbing pipework, and major electrical containment.
- Adjust duct positions, riser locations and bulkheads while the design is still on paper.
By resolving these issues at design stage, project teams avoid redesigning beams, lowering ceilings or re-routing ductwork after the plasterboard is already up.
Using Duco BIM models in ventilation design
Duco provides an extensive BIM library with Revit and DWG files for its ventilation units, window vents, louvres and DucoFlex duct components. These BIM models for ventilation are available as direct downloads and via platforms like BIMobject and MEPcontent.
In practice, design teams can:
- Place Duco MVHR units (for example, DucoBox Energy models) in plant rooms with correct spigot locations, drainage and clearances.
- Use DucoFlex duct components to check that risers and ceiling zones can physically accommodate bends, junctions and reducers.
- Insert Duco external louvres and window vents into façade models to coordinate appearance, position and spacing relative to other façade elements.
Because these objects are parametric, sizes and variants can be switched while connections and bounding boxes remain correct. When EcoVent is familiar with the same product families, everyone is effectively working from the same digital and physical playbook.
Using Domus BIM/Revit files and drawing support
Domus Ventilation also offers a free ventilation BIM library and a Revit Family Manager plug-in. The content covers MVHR units, MEV systems, rigid ductwork, radial semi-rigid ducts, attenuators and insulated ducting.
This creates several benefits for the CAD/BIM workflow:
- MVHR units and duct components can be dragged and dropped directly into Revit, with accurate product data, airflows and dimensions.
- Airflow parameters at grilles and valves can be used to estimate pressure loss and check that duct sizes and MVHR ductwork layout remain sensible.
- Domus provides a drawing service that can generate layouts and bills of materials in AutoCAD or Revit when their systems are specified, which can then be coordinated with the main model.
For Irish residential projects that use Domus ducting or equipment, this kind of support can save many hours of manual drafting. It also gives EcoVent and the architect a common reference when discussing adjustments to the ventilation CAD model.
Minimum level of detail that usually works
For most one-off houses and smaller residential blocks, there is no need to model every fitting. A practical level of detail for ventilation CAD and ventilation BIM is:
- MVHR/MEV units and key manifold boxes close to real size
- main ducts with correct diameters and realistic alignment
- branch ducts modelled to each valve with believable bends
- external terminals (wall or roof louvres, cowls) in correct positions and sizes
Smaller items such as flexible connectors, clips and detailed mounting arrangements can stay in the specification and standard details. The digital model carries the big decisions; and the installers handle the finer installation points on site, guided by that model.
When a specialist ventilation designer adds value
A strong architectural model is a major advantage. Nevertheless, some projects benefit from an additional specialist viewpoint:
- tight ceiling zones with multiple services competing for space
- complex split-level houses with long duct runs and several risers
- demanding acoustic or fire-compartmentation constraints that are hard to resolve in 2D
- projects that require a full MVHR commissioning certificate and validation report, not just a sketch layout
In these situations, a ventilation specialist can work inside the existing ventilation CAD or ventilation BIM environment, using Duco or Domus content (and other manufacturers as needed) to produce buildable layouts. EcoVent’s role is to bridge design and installation: we take what we know from site, commissioning and troubleshooting, and feed it back into the CAD model so the final design is both coordinated on screen and practical in the ceiling void.