Preservation FAQ.

The standard describes how an acceptable climate band is derived from the room's own historical climate, rather than setting a universal target value. It focuses on humidity fluctuations, because those are what cause mechanical damage to hygroscopic materials. So it does not say that every collection has to sit at a particular figure.

Because the object is acclimatised to the room it stands in. An abrupt shift to a textbook ideal forces the material through a movement it would not otherwise have had. A stable climate that sits a little away from the ideal is usually better than a quick route towards it.

At least 45 days before a safe band is shown. A full year before the band counts as established, with both a summer and a winter profile. Until then the status reads Learning, which is more honest than showing a band that will not hold.

Choose for the most sensitive thing the sensor is there to protect. Robust (±10%) suits stone, metal and glass. Medium (±7%) suits canvas and paper. Sensitive (±5%) suits wooden panels, inlaid and polychrome wood, and historical objects. If in doubt, the narrower band is the cautious choice.

Look at the analysis chart to see where the excursions fall. If they coincide with the start of the heating season, with visitor numbers, with airing, or with a change in the weather, that points straight at the cause. The fix is usually to slow the rate of change — heating more gradually, airing for shorter periods more often, or dehumidifying rather than heating.

That there is microscopic growth: conditions have been favourable enough for spores to be active, but nothing is visible yet. It is the early warning, and the right moment to do something about the humidity level — not a sign that damage has already been done.

There is no single limit, because it depends on temperature, material and duration. As a guide, sustained relative humidity above 80% is clearly in the risk zone for sensitive materials, while 65–75% over a long period can be enough. That is precisely why the model calculates the combination over time instead of using a fixed threshold.

No. Every sensor with temperature and humidity in the RoomAlyzer Air system is given material class SQ2 automatically and is included in the calculation. Administration → Mould VTT is where you change the class, adjust the drying rate or opt a sensor out.

Because the figure is still being fetched or calculated in the background. The list refreshes itself after a few seconds. Note that a dash in a report means the fetch failed — not that there is no risk.

Yes. If the climate becomes drier or colder, growth is inhibited and the index falls. That is why the trend is part of the assessment: a falling curve means the strategy your team has put in place is working.

No. Classic conservation heating is a system that controls the heat via a hygrostat in order to keep humidity down. Heating waste is an estimate of how much warmer the room has been than preservation required. We calculate — we do not control.

That depends entirely on how far above the setpoint you are and how long your heating season lasts. The analysis shows your own figure for 24 hours, 7 days and 30 days. We do not quote a general savings figure, because it would be a guess about your building.

Because May to September always counts as outside the heating season. Warmth above target in that period comes from the sun and from internal sources, not from the heating, and it would be wrong to call it heating waste. In the winter months, a seven-day rolling average of the outdoor temperature decides whether it really is heating season.

The dynamic one is energy-optimal, because it lets the humidity limit follow the risk at the current temperature. The static one is easier to explain and to check. If you have a preservation policy with a fixed humidity limit, static often makes the most sense; if you are looking for the savings, dynamic is where to look.

Not much, and it is all in one place in RoomAlyzer Air when you begin: you simply set up sensors measuring temperature and humidity in the room, then enter the building data under Administration → Heating waste — floor area, insulation, heat source and strategy. With those figures, the difference between the measured and the desired temperature can be converted into energy and pounds.

That depends on the size of the room and on how uniform the climate is. A store with cold external walls and a warm middle is really several climates, and a single sensor in the centre of the room will not catch the condensation risk at the wall. Start with the most exposed places: external walls, floor level, close to the most vulnerable objects.

It varies. The mould index and the Preservation Index start to make sense after a few weeks. EN 15757 needs at least 45 days of data before a safe band is shown, and a full year before the seasonal profile is complete. ASHRAE requires a full year with at least around 8,000 valid hours. The system says clearly when the history is too short, rather than showing a figure that will not hold.

Yes, and that is often where they are worth the most. A church or an unheated store cannot be controlled with a thermostat, but it can be controlled through behaviour: when to air the room, when to heat for a service, whether to dehumidify. For that there is also the ventilation analysis, a forecast of when it is safe to open the windows.

Then the room's figures are not the right answer for that object. Consider a sensor close to it, or a display case with its own climate. The analyses describe the climate the sensor is standing in — they do not know what the room contains, beyond the material class you have set yourselves.

Yes. Any sensor that measures both temperature and relative humidity can feed into the preservation analyses, and there is no manual sign-up for mould, ASHRAE or Bizot. What separates preservation from indoor climate is not the hardware, but what the figures are held up against.