Delivering a healthy villa means designing and building the building envelope, ventilation, Five-Constant, and smart-control and security systems as one system, so that indoor temperature, humidity, CO₂, noise, and formaldehyde hold at the values written into the contract over the long term. For detached and townhouse homes of 300㎡ and above.
Villas differ from ordinary homes in three ways: a larger cumulative volume of materials means a higher total emission load; complex spaces such as double-height voids, basements, and stairwells make air distribution difficult; and seven systems competing within the same ceiling plane create interface conflicts. Because of these three, villa work cannot copy apartment practice.
Mainly three things: the cumulative volume of materials, the complexity of the spaces, and interface conflicts between systems.
When floor area grows fivefold, the boards, adhesives, and coatings do not simply grow fivefold, because they spread across more rooms, more junctions, and more closing details. More emission sources mean ventilation dilution delivers diminishing returns — which is why many villas left to air out for six months still smell after one night with the windows shut.
Complexity of space brings problems of air distribution. When a double-height living room, a two-storey stairwell, and a sealed basement volume all exist in the same house, supply and return air designed from apartment experience produces the familiar symptoms: stuffy upstairs, cold downstairs, damp in the basement.
The most overlooked is interface conflict. Air conditioning, underfloor heating, ventilation, dehumidification, smart control, power, and low-voltage — seven systems squeezed into the same ceiling void. Whoever claims space first decides the build quality of every system that follows.coordinated drawingssolve exactly this sequencing problem.
Fresh-air volume must satisfy two calculations at once, taking the larger: 30m³/h per person (the national standard minimum), and air changes of ≥2 per hour in quiet zones and ≥1.5 per hour in activity zones. 300㎡ needs about 350m³/h, 500㎡ about 550m³/h, and 800㎡ about 850m³/h, with the final figure calculated room by room.
There are two calculations, and both must be met, with the larger taken: per person, 30m³ per hour is the national standard minimum; by air change rate, no less than 2 per hour in quiet zones and 1.5 per hour in activity zones. The per-person method secures air quality; the air-change method secures the capacity to dilute pollutants.
| Floor area | Regular occupants | Per-person minimum | Air-change method (at 3m clear height) | Recommended design value |
|---|---|---|---|---|
| 300㎡ | 4 people | 120 m³/h | Depends on room layout; typically 250–350 m³/h | 350 m³/h |
| 500㎡ | 5–6 people | 180 m³/h | Depends on room layout; typically 450–600 m³/h | 550 m³/h |
| 800㎡ | 6–8 people | 240 m³/h | Depends on room layout; typically 700–950 m³/h | 850 m³/h |
The table gives reference ranges for the concept stage. Actual values must be calculated room by room according to layout, ceiling height, orientation, and the airtightness of doors and windows, and are governed by the design drawings.
One conversion we are often asked about: steady-state indoor CO₂ is roughly the outdoor baseline (about 420ppm) plus human exhalation divided by fresh air per person. Holding a room at 800ppm takes about 50m³/h per person; holding it at 500ppm takes about 225m³/h per person, which is not realistic in a home. Sowe commit to 800ppm, not a number we cannot deliver.
The three follow different logic: a double-height living room needs vertical displacement or floor-level supply to avoid thermal stratification; a basement needs leaks and thermal bridges resolved before dehumidification is discussed; a home cinema needs silenced supply and return grilles, the unit moved away from the room, and duct velocity held below 4m/s.
These three spaces are where villas most often go wrong, and each is handled differently.
For 500㎡, design sign-off to handover usually takes 6–9 months: 1–1.5 months of design, 2–3 months of concealed works, 2–3 months of finishes and equipment installation, and 3–4 weeks of commissioning and CMA re-testing. The time goes mainly into drawing coordination and pre-handover commissioning, not installation.
For 500㎡, design sign-off to handover usually takes 6–9 months: 1–1.5 months of design, 2–3 months of concealed works, 2–3 months of finishes and equipment installation, and 3–4 weeks of commissioning and CMA re-testing.
One clarification: for health-related systems the time cost sits mainly outside installation, in two places — coordinating interfaces between disciplines at the drawing stage, and commissioning and testing before handover.The full description of the seven stageslists the points at each stage where the client needs to be involved.
The budget has five parts: the building envelope and wall system; ventilation and Five-Constant equipment with its ductwork; smart control and security; construction and installation; and commissioning and testing. We do not advise comparing quotes by price per square metre, because the system specifications behind different quotes can be entirely different.
The budget usually has five parts: the building envelope and wall system; ventilation and Five-Constant equipment with its ductwork; smart control and security; construction and installation; and commissioning and testing. Their proportions vary with the house type and the specification chosen, and must be costed against the actual drawings.
We do not advise comparing quotes on price per square metre. Two quotes at the same figure may differ: one includes the thermal-storage wall and the other does not, one uses full fresh air and the other fresh air with return, one specifies imported units and the other domestic. On paper these differ by a single word; in daily experience they differ by an order of magnitude. Look atWhich Metrics the Contract Commits To, which tells you more about value than the total price.
Three cases where we advise against it: the structure cannot carry the equipment load or accept the openings; only a partial renovation is planned but whole-home metrics are demanded; or the budget is so far from the target metrics that the only proposal left is a lowered standard. Health systems usually fail because someone promised a metric they could not deliver.
Three cases where we will say plainly that the work is not suitable: the structure cannot carry the equipment load or accept the openings; the owner plans only a partial renovation but wants whole-home metrics; or the budget is so far from the target metrics that the only proposal left is a lowered standard.
We set out the unsuitable cases up front because health-related systems more often fail by promising a metric that cannot be met than by buying the wrong equipment. In that situation, changing the plan is more responsible than pressing ahead.
Not necessarily. Below 300㎡ of floor area, or where ceiling height is limited, or where the owner is not especially sensitive to temperature and humidity, full fresh air with local dehumidification and room-by-room air conditioning solves most of the problem. Five-Constant earns its keep most clearly in large homes with many rooms, where differences in temperature are felt.
Where a basement has a continuous moisture source — soil damp, leak points — and connects to the space above, slight positive pressure effectively stops moisture and odours spreading upward. If the basement has independent external wall waterproofing and a complete dehumidification design, positive pressure is not essential, but it usually remains the best value for money.
Noise comes mainly from three places: the unit itself, excessive duct velocity, and airflow at the supply and return grilles. The controls are to keep the unit away from bedrooms, hold duct velocity below 4m/s, and silence the grilles. Do these three and a bedroom can stay below 30dB(A) at night.
Yes, within limits. A finished home can take surface-mounted or semi-surface-mounted ventilation, standalone dehumidification, and local smart control; whole-home Five-Constant usually requires a full renovation because it involves floors and ceilings. The exact boundaries are on the Renovation page.
We cover Shanghai, Jiangsu, and Zhejiang. Keeping projects within these three regions is how we protect response times during construction and in later servicing.
To find out whether your house is a fit and how a scheme would work, call us or add us on WeChat. We answer one to one.