Royal Commission on the ancient and historical monuments of Scotland

[1] This noble institution is planning an archive and storage building near the Edinburgh docks on the Firth of Forth. [2][3][4]

The architects concept was already developed when we were invited to advise on climate control. [5][6]

[7][8] The modular system consisted of relatively small rooms stacked five wide and three high. For our first modelling exercise, we took a single room in the middle of the stack. [9] The outdoor climate would influence the inside through the short end wall, and through limited air exchange. The inside climate, fixed for human comfort, would influence the room through the opposite short wall. The other walls, floor and ceiling would have no effect, since they were adjacent to identical modules.

We played with alternative wall constructions at each end and produced an optimal indoor climate

[10] This climate is produced by BSim, which is a Danish computer model for simulating the hygrothermal behaviour of buildings. There are several such programs used by consulting engineers. We have not confused ourselves by comparing models. None of these models can be considered scientific, because they are in secret code. Later, you will see how frustrating this can be.

The indoor climate is fine in winter but too humid in summer. We used a constant 20C corridor climate. In reality it would be cooler in winter and hotter in summer, but even so, this system for climate control is unsatisfactory.

Fortunately, the client had second thoughts about populating the rooms on the human, west side of the archive buildings, so we were free to try other climate moderating ideas. In particular we expored the possibility of solar heating

[11] We also extended the model into a whole stack of modules, so we could explore the use of ground heat and solar heat on the roof. In this wire diagram you see the virtual building. Note that the west wall (towards you) is half window.

[12] We also applied some humidity buffering by making paper partitions. The climate is now quite good, remembering that the RH trace is very compressed in time, so the spikiness is not dangerous, considering that there is very little buffer compared with the stuffed archive. Also, the archives will be mostly boxed, giving a further enormous buffering of RH. In existing passive archives, the RH tends to be just as smooth as the temperature trace in this diagram.

[13] In this diagram the faint trace shows the room without any humidity buffer. Notice the strange effect on the temperature, which is inexplicable and maybe an artifact of the modelling program. The moisture transfer programming has been a recent addition to this, and to other modelling programs. One has to treat these predictions with caution. Fortunately, we have some real archives to support the general indications of these virtual realities.