**7. Weather data**

310 Solar Radiation

The last example, the Rautatalo building, brings the reader back to the efforts of the modern movement in architecture to control radiation. With 40 skylights it was subsequently adapted to many projects around the world, which generally speaking fared less well than

Fig. 24. The Rautatalo building of 1955 by Alvar Aalto, Helsinki. Simulation of 40 skylights (8\*5), performed in June with direct sunlight and monitored on 21st of June 2011. Values in

This climate-responsive building would remind the reader that, in order to produce

the original for climatic and economic circumstances.

Fig. 25. Solar Chart of Helsinki. Latitude 61.16 degrees north

universal results there is the need to consider local weather parameters.

lux

As figure 25 tries to evoke, weather data for radiation must be based on sunlight availability. At the time of writing this chapter, many measurements of horizontal irradiation in the world have been recorded and also correlations for vertical surfaces of different orientations are available. The author recommends the following based on altitude θ and azimuth φ from the south direction (in radians).

$$E\_v = 4000 \ast \theta^{1.3} + 12000 \ast \sin^{0.3} \theta \ast \cos^{1.3} \theta \ast \left[ (2 + \cos \varphi) / (3 - \cos \varphi) \right] \tag{38}$$

The author's software is capable of combining these results with sunlight probability for any location in the world to obtain annual, monthly and hourly distribution of irradiance on vertical and horizontal surfaces. (See tables 1 and 2).


Table 1. Mean annual radiation (W/m2) by orientation in Rome. Italy. Latitude= 43.41º North


Table 2. Mean annual radiation (W/m2) by orientation in Quito. Ecuador. Latitude= 0.3º South

Nonetheless, the former data are averages and not a substitute for measured registers and much less for instant values. Only simultaneous monitoring at intelligent buildings can achieve real time input in our simulation model.

What is recommended in this chapter is a likely figure intended to handle the problem with reasonable accuracy in the frequent absence of more detailed information. This will help to design building features that save energy and comply with the most relevant weather conditions at each climate6.

<sup>6</sup> Klymax κλίμάξ in Greek from where the word climate derives, means "stairway".
