Five-Constant refers to five indoor environmental metrics: constant temperature, humidity, oxygen, cleanliness, and quiet. Laoliu Healthy Mansion adds constant water quality for a total of six, and writes each target value, governing standard, test condition, and pass/fail method into the contract. Before handover, an independent third party holding CMA accreditation re-tests every item.
Constant temperature, humidity, oxygen, cleanliness, and quiet. Together these five cover the main ways the body registers a room: warm or cold, damp or dry, stuffy or fresh, clean or dirty, loud or quiet. We add constant water quality (drinking water), because water too has defined test methods and a clear boundary of responsibility, so it can be written into a contract.
Constant temperature, humidity, oxygen, cleanliness, and quiet. Together these five cover the main ways the body registers a room: warm or cold, damp or dry, stuffy or fresh, clean or dirty, loud or quiet.
Beyond these five we addconstant water quality, because drinking water quality is part of living health as well, and it comes with defined test methods (TDS, turbidity, residual chlorine) and a clear boundary of responsibility, so it can be written into the contract. That is why the table below runs to six rows.
The difference lies in what each system is solving. Central air conditioning plus underfloor heating solves temperature; Five-Constant solves five things at once: temperature, humidity, oxygen, cleanliness, and noise. The gap is most visible in the plum-rain season and in winter with the windows shut — air conditioning has limited dehumidification capacity and cannot address CO₂ buildup. Those two points are the dividing line.
The difference is what each system is solving. Central air conditioning plus underfloor heating solves temperature; Five-Constant solves five things: temperature, humidity, oxygen, cleanliness, and noise.
The gap is most visible in the plum-rain season and in winter with the windows shut: air conditioning has limited dehumidification capacity, indoor humidity in the plum-rain season often stays above 70%, and CO₂ climbs steadily once the windows close. Air conditioning solves neither. A more detailed comparison is onthe Large Flats page, which lists all seven.
The six map to GB 50736 (temperature), GB/T 18883-2022 (humidity, CO₂, formaldehyde), GB 50118 (noise), and GB 5749 (drinking water). Each entry must state four columns: target value, standard number, test conditions, and test method. Miss one and the commitment can no longer be judged.
The table below is the one that deserves the closest scrutiny on this site. Every row gives a target value, a reference standard, test conditions, and a test method — because that is precisely what separates a commitment from a slogan.
| Metric | Target | Reference standard | Test conditions | Test method |
|---|---|---|---|---|
| Constant temperature | 22–24℃, with ≤2℃ variation across the home | GB 50736 — Design Code for Heating, Ventilation, and Air Conditioning of Civil Buildings | Windows and doors closed, after 24h of steady operation | Thermometer readings at each room center, 1.1m above the floor |
| Constant humidity | 50±5% (wine cellar 60–70%) | GB/T 18883-2022 — Indoor Air Quality Standard | As above | Temperature and humidity logger, continuous 24h recording |
| Constant oxygen | CO₂ ≤800ppm, and ≤500ppm above outdoor air | GB/T 18883-2022; Assessment Standard for Healthy Building, excellent grade | Design occupancy present indoors, windows and doors closed | NDIR CO₂ meter, multi-point sampling |
| Constant cleanliness | Formaldehyde ≤0.06 mg/m³; PM2.5 to the design class | GB/T 18883-2022 (formaldehyde limit 0.08 mg/m³) | Windows and doors closed for 1h (formaldehyde); standard sampling duration | Sampled by a CMA-accredited laboratory; spectrophotometric method |
| Constant quiet | ≤30 dB(A) at night | GB 50118 — Code for Sound Insulation Design of Civil Buildings | Night-time hours, system in normal operation | Integrating sound level meter, A-weighted, measured at room center |
| constant water quality | TDS ≤10 | GB 5749 — Standards for Drinking Water Quality (TDS limit 1000) | Sample taken from the terminal tap once flow is stable | Portable TDS pen or laboratory analysis |
Target values in the table are our own delivery commitments, and several are stricter than the national limits. Testing must be carried out by a third-party body holding CMA accreditation; specific test items and pass/fail methods follow the contract annex.
Because people register a temperature difference more sharply than an absolute temperature. Set the whole house to 23℃ while rooms drift between 21℃ and 25℃, and the home simply feels wrong somewhere. The 2℃ figure comes from real-world feedback and from the general expectations of international healthy-building assessment systems. Meeting it depends on similar heat loads, even air distribution, and an envelope without obvious thermal bridges.
Because people register a temperature difference more sharply than an absolute temperature. Set both rooms to 23℃, yet the main bedroom sits at 25℃ and the study at 21℃, and walking between them makes the difference plain. The discomfort comes from imbalance, not from an unsuitable temperature.
That 2℃ figure comes from real-world feedback and from the general expectations of international healthy-building assessment systems. Reaching it is not a matter of specifying a larger air conditioner, but of bringing each room's heat load close together, distributing supply air evenly, and keeping obvious thermal bridges out of the envelope. This is also one of the reasonsthermal-storage wallsexist: letting the walls take part in temperature control narrows the difference between rooms.
500ppm is not physically achievable. Steady-state indoor concentration is roughly the outdoor baseline of 420ppm plus what one person exhales divided by the fresh-air rate per person. Holding 500ppm would require 225m³/h per person, and no home can absorb the noise, duct size, and energy that implies. 800ppm corresponds to about 50m³/h per person, is achievable in steady operation, and is stricter than the national limit of 1000ppm.
Because 500ppm is not physically achievable.
Steady-state indoor CO₂ is roughly the outdoor baseline (about 420ppm) plus what one person exhales divided by the fresh-air rate per person. To hold 500ppm you would need around 225m³/h per person — 225 cubic meters of air exchanged for every person, every hour. At that scale, noise, duct size, and energy demand become unacceptable in a home.
800ppm corresponds to about 50m³/h per person, which can be held steadily while staying quiet, serviceable, and reasonable in energy use. It is stricter than the 1000ppm limit in GB/T 18883-2022 and better than what most homes actually achieve.
Formaldehyde is tested with windows and doors closed for 1 hour, as GB/T 18883-2022 requires. CO₂, temperature, and humidity are measured with the design occupancy present and the system running steadily. Sampling points follow floor area and room count, generally one per enclosed room. The testing body must hold CMA accreditation, and the report must carry the CMA mark and the standard number it was tested against.
Formaldehyde testing requires windows and doors closed for 1 hour, as GB/T 18883-2022 specifies, to mimic a home in normal closed use. CO₂, temperature, and humidity, by contrast, must be measured with the design occupancy present and the system running steadily — otherwise the readings mean nothing.
The number of sampling points follows floor area: generally one per enclosed room, with additional points in large spaces such as the living room. The testing body must hold CMA accreditation, and the report must show the CMA mark and the standard it was tested against.
We follow the contract: first we trace the cause. Where the cause falls within our scope, we rectify it and re-test, and we bear the cost. A failed result does not always originate in the system itself — door and window airtightness, emissions from furniture the owner bought separately, and the season of testing all affect the outcome. That is why the contract must define the test conditions precisely.
We follow the contract: first we trace the cause. Where the cause falls within our scope, we rectify it and re-test, at our cost. The specific terms are on theContract & Warrantypage.
It is worth stating plainly that a failed result does not always originate in the system itself. Door and window airtightness, emissions from furniture the owner bought separately, and the season in which testing takes place all affect the outcome. That is why the contract must define the test conditions precisely — otherwise a dispute leaves both sides talking past each other.
Higher than ordinary air conditioning plus underfloor heating, mainly because fans and humidity control run continuously. The exact figure depends on floor area, climate zone, envelope performance, and setpoint, and the range is wide, so we do not quote a single number. With a well-built envelope the gap narrows considerably.
No, and we advise against it. Open windows break the indoor pressure and humidity balance and push the system into a compensating mode. The system already brings in fresh air continuously, so opening a window only lowers efficiency.
Usually not. Humidity control is built in and adds moisture whenever levels fall below the set band. Extremely dry regions or severe cold snaps may need a supplement, but the usual Jiangsu, Zhejiang, and Shanghai climate does not.
Three-Constant usually means constant temperature, humidity, and oxygen. Five-Constant adds constant cleanliness and constant quiet. The difference is whether measurable commitments are made for particulates and noise.
Redundancy and a manual bypass are built into the design, so basic ventilation can run independently if the main controller fails. Response times within the warranty period follow the contract; see the Contract & Warranty page for the specifics.
They may be presenting design conditions, an empty unit, or a short measurement as a long-term figure. Steady-state concentration can be calculated, so ask for the test conditions and the measured report rather than judging by a marketing number.
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.