Times have certainly changed, as has the architecture in these post-Soviet days of independence. The old buildings, and the people who designed and built them, still exist. Some parts of Kazakhstan are in good repair and upkeep, while other parts look like an old amusement park that hasn't been used in years. In some cases cranes and forklifts stand in the exact places they were in when independence was declared and government money ran out. Rusted and covered in weeds and grass, much of the Soviet architecture and the people occupying it are in desperate need of help. This picture is further complicated and contrasted by the introduction of new buildings and new wealth by some people in Kazakhstan.
2. Watson and Labs matrix: Design Strategies
In their book (1973) about climatic responsive applications, Watson and Labs created an original matrix that is able to explain the different design strategies that could be used in different situations and climates; much attention in the matrix is given to the heat sinks and sources.
The two climates under analysis (Colombo and Semipalatinsk) are so much different between them that we divided completely this analysis to understand better what to do in each city during the different seasons.
- Semipalatinsk (Kazakhstan) - Winter period
The winter period of this kind of climate is affected by very low temperatures that reaches also values of -40 °C during the colder nights, while a bit lower than 0 °C during daytime. This means that the need of heating would basically be required continuously during the cold season; however, some measures might and should be adopted in order to optimize these needs and to avoid an excessive waste of energy and an overproduction of CO2.
The ways in which this idea could be accomplished are numerous and rely on all the different kinds of energy transfers known in nature: conduction, ventilation, radiation and moisture transfer are all affecting the indoor conditions of buildings and we have to act on these factors in order to reach our goals.
During the winter period, the main concerns are obviously the increasing of heat gains and the reduction of heat losses; we will now try to understand how this aim will influence our design strategies for the different kinds of energy transfers.
Conduction/Convection One of the most important aspects that needs to be cured about conduction and convection heat transfers is the improvement of the heat storage, when available, in order to increase the heat gains during cold periods. The bigger heat capacity storage that can be used in nature is, of course, the soil: the advantage of soil is mainly due to the fact that, having the possibility to go very deep (depending of course from site characteristics) below ground level, we can have a very large mass to be used as storage. Also, the advantage in using soil instead of other sources (like, for example, air) for heat transfer is related to the stable temperature of the soil itself, that even during very cold winters is not affected so much from the external low temperatures, keeping its temperature nearer to the one that we want inside our building: this could affect positively the efficiency of a possible heat pump device.
Also, in terms of conduction, it is very important to reduce heat transfers from inside to outside: this can be accomplished working on walls stratigraphy in order to act directly on the thermal conductance of external partitions, fundamental step in the insulation of the building itself.
Ventilation The aspects related to ventilation are usually the most difficult to predict, because of the high range of variability that we have in terms of radiation, temperatures and all those parameters that affect the external air. Anyhow, during the cold periods it is much easier and ‘safer’ to reduce any kind of infiltration and air exchanges (as much as possible but always taking care of indoor air quality) from the external environment. Sometimes, in the presence of strong radiations from the sun, it could be an advantage to warm up the external air naturally before promoting the exchange between this air and the internal one; however, in a very rigid climate like Semipalatinsk, this idea would not represent a good solution because the sun radiative power would not be able to heat the external air so much to reach a temperature even near the indoor thermal comfort.
Radiation Radiation is obviously one of the most intuitive methods to increase heat gains of a building by improving the solar gains, mainly through its transparent surfaces. For this reason, it would be very good to act on the orientation and characteristics of windows and openings during the design phase of a building in order to maximize the heat gains due to the sun radiation. Being during winter solstice the sun elevation in Semipalatinsk very low (reaching not more than 18°), a possible way to increase solar gains could be avoiding the use of vertical shading devices that could negatively affect this parameter: however this study is much more complicated and should be analysed for each situation, because solar beams are not only influencing thermal comfort but also visual comfort and internal lighting, so the solutions can be very different according to the different destination or type of building under analysis.
- Semipalatinsk (Kazakhstan) - Summer period
As we know from previous homeworks the climate of Semipalatinsk, that is very rigid during winter, is quite moderate during the hot seasons and this brings to low cooling needs. For this reason, the main design strategies of this kind of cities are mainly based on the winter period to reduce heating needs: orientation, openings, partitions are designed taking care mostly of the cold part of the year. However, some solutions can be studied also for the few days in which the temperature rises above the comfort ranges; for example, in some days during July the temperature reaches high values and a South window exposition could make it even higher: this is why an external movable shading device could be effective in this situation and useful to avoid an internal overheating.
Also, having quite low external temperature during the night of the hottest months, the external air could be used in order to have a night purge cooling of our indoor space to avoid that either works for air quality; this is of course possible in non-residential buildings, which are not supposed to be occupied during night hours.
- Colombo (Sri Lanka)
The past analyses carried on about this city have shown the fact that for the city of Colombo it is basically not possible to define an ‘heating season’, being the average dry bulb temperature of January, that is the coldest month, almost 27 °C. For this reason the design strategies of such an hot climate have as common aim the reduction of cooling energy needs and the de-humidification of the indoor space; these studies have to be carried on always taking care of the different thermal comfort ranges and perceived temperatures of the two different locations, related to people habits and culture.
We wanted to analyse how we could act on different thermal transfer means in order to achieve the goal of reducing energy needs for cooling.
Conduction/Convection/Radiation In terms of conductive and convective heat transfer modes, the best idea in this situation is to increase the heat transfer from indoor environment to the outside. This can be reached acting on the properties of the external partitions or also or glazing characteristics. For example, in this hot climate it would be helpful to use a glazing type that is able to reflect solar radiation coming from the sun but at the same time to let the heat flow from inside to outside without creating a green-house effect; this can be obtained, for example, with a glazing type that is reflective in its external layer but not on the inner side. Also, in this study we have to give importance to the lighting: the characteristics of the openings, in fact, cannot be decided without taking care of internal visual comfort; the use of clear reflective windows can help a lot in our situation because it could keep the heat outside without hinder the light access. However, the openings area has to be as low as possible, being it the main cause of heat gains from the outside.
In terms of external partitions, in fact, it would be preferable to have thick walls, with an high density (using for example stones) with great thermal inertia in order to keep the inside temperature below a certain threshold for an higher amount of time.
Ventilation There are two ways in which ventilation might be positively used in this kind of hot climates: reducing air exchanges and infiltrations with external air when the outside temperature is high and encourage this exchange during the few colder nights. In order to avoid air leakages and infiltrations, it is fundamental to pay much attention to the design of openings, not only reducing their area but also properly designing the connections between opaque and transparent parts of the envelope. This topic also depends from the building destination. In offices, for example, the thermal mass can also be used in roof/floors of the building in order to avoid daily overheating, linking this system to a proper night purge cooling that permits the release of this accumulated energy during the night towards external environment. In this case, however, it is important to properly study the timing of the heat released in order to avoid that it will not match the time of night purge cooling: to do this, a proper study of the thermal inertia and materials characteristic is needed.