So much of our lives revolves around managing heat. From our bodies to our homes, we shape both the internal and external environment to suit our needs. As in Lechner’s Heating, Cooling, and Lighting, there are forms of progressive barriers that promote our thermal comfort like clothing, canopy beds, and the walls of our buildings. Even our skin is a fascinating envelope of heat that works like a “biological machine” as Lechner said to dissipate waste heat and control heat loss.
As described in a previous blog post, we should not strive to build the same well-controlled, air conditioned, and heated box to fit in every environment, but work towards discovering a diverse range of ways of passive design strategies to naturally reap rewards of comfort from what the environment provides. Thus, there is value in looking at our original building methods. According to Daniels from The Technology of Ecological Building, buildings of the past were characterized by “small windows” (to reduce heat loss), “building masses with high storage capabilities”, and “low standards for heating and sanitary systems” (requiring less energy and complications). In the example of materiality, the building masses of natural materials that stored the heat so well in colder seasons did not overdo the temperature in the hotter seasons. Also heating by tile stoves could heat multiple rooms through a system of shafts and wood combustion did not produce damaging products released into the environment.
One interesting example of an old structure is the Water Castle in Glucksburg. It created an unintended climate from building a water moat around it. Although Daniels says it’s original purpose was “for safety and protection”, the moat produced many facets of comfort. It reflected more sunlight towards windows, while the surrounding air was made cooler by the water’s surface (reducing summer’s antagonizing heat), and retains heat somewhat at night because water cools slowly (due to it’s high retention of thermal energy). Thus looking at instances of purely natural features of comfort with passive construction shows it’s use and ease.
In a modern mindset of creating evermore progressive barriers to the wilds of the outside (with advanced air-conditioning and heating), the treasures of potential passive energy sources from wind, water, and sun, are left unharnessed. Why should we employ such effort in extracting and transporting fuel from below the surface, when energy is all around us? In accordance with this week’s workshop on reading the psychrometric chart for comfort using different design strategies, there was a lot of comparisons between passive and active designs. Although the highest hitter in terms of comfort could be found in air conditioning and heating, much of the energy used was unnecessary when looking at simpler passive designs that could produce a bulk of the same effect in a more direct and succinct way. For example matching wind protection designs for a structure in a very windy environment better targets the problem than simply using the default method of turning up the heat. Thus, in these respects, we should use more passive energy designs to partake in the stream of energy that already flows around us -using the system instead of creating barriers to it.
Lechner, Norbert. Heating, Lighting, and Cooling, Chapter 4
Week 7 Workshop Exercise
San Salvador, capital of El Salvador
Understanding the Chart
1. The dewpoint is 52 degrees Fahrenheit.
2. In this situation the humidity ratio would change by .11. To calculate this ratio change you would first calculate the humidity ratio of the outside and inside conditions and then find the difference by subtraction.
3. The relative humidity would be about 40%.
1. San Salvador, located in El Salvador of Central America, is a consistently hot-and-humid climate city.
2. San Salvador is a sunny city, being close to the equator. Thus by the tilt of the Earth, it is biased towards warm weather. It’s tropical weather lends towards little temperature change between seasons.
3. The temperature falls in the comfort zone most often in September (similarly from July to November).
4. The most effective passive design strategies in expanding the comfort zone are: sun shading of windows, natural ventilation cooling, dehumidification only, and fan-forced ventilation cooling; while the least effective passive design strategies are: wind protection of outdoor spaces (it’s not a very windy city), humidification only, and passive solar direct gain low mass.
5. Yes, it is possible to achieve a high percentage of comfort in San Salvador’s comfort using only passive design strategies. The biggest temperature and humidity design challenges derive from San Salvador’s variability in rainy and dry seasons, because the design strategies have to adjust to each mode of comfort.