Human comfort is at the center of our lives. The more comfort we have, the more successful we appear, the more productive we become, and the happier we feel. It is no wonder that advertisements and bug business thrive on providing us with the next most significant breakthrough in comfort. In this blog we will review some fundamentals of heating and cooling as well as a few strategies on implementing them into our designs.
Virgin Galactic created a company around creating a comfortable travel experience to the edge of space. I count the years to their first edge of the world hotel opens. Stock market trading hinges on how confident people are with the economy, a business, or the latest trend; when it comes to our homes, comfort and convenience reign, King. How? Confident Control. What happens, when, how much, and why does it happen? We control the view, the breeze, the sun, the tv, the coffee maker, the stovetop, the temperature, and the environment. The more control we have, the less it bothers us; we set it on Autopilot and make minor adjustments when needed or wanted. Wouldn’t it be nice if every part of our lives ran so smoothly?
When it comes to comfort, temperature & humidity play a critical path at its core. We are immediately aware that when we are too hot or too cold, our bodies react to extremes in an auto-pilot scenario. If exposed to extreme cold, your body will automatically pump blood away from extremities and closer to organs as primary requirements for life. On a day-to-day basis, we seek warm, cool, wet, and dry conditions depending on external forces. When it’s frigid, we seek warmth; when it’s sweltering, we seek cool when we are drenched, we seek dry; and when we are dehydrated, we seek moisture.
The home, especially in recent years, has become a control center for our lives. We operate our lives, careers, family, hobbies, and love from the confines of its walls, floors, rooves, and ceilings. As Architects, we understand the science of how to create the most controlled environment within a home so that you have the highest level of control over your comfort. So that, like the body, your home will automatically adjust itself to maintain the health of its vital organs. We employ systems of comfort by applying the latest technological advancements and pairing the natural passive strategies inherent to our beautiful planet. God is in the details, and those details are felt by everyone, whether done well or poorly, on a large scale and the micro.
Controlling the home’s hot, cold, dry, and wet conditions has many facets. A few big ticket numbers are the different kinds of natural systems available. First, we must heat; our natural sources include fire, the sun, and the earth. We can manufacture heat by burning resources like wood, gas, coal, or oil. We can absorb the suns radiation using materials and technology. Or we can take advantage of the earth’s natural ability to maintain consistent ground temperature, produce energy through the flow of water, as well as change atmospheric temperatures. Once we have procured a source, we have to move the heat throughout the space via air, water (or some other fluid), or even metal wire (Resistance of electricity/electrons produces the heat source.)
Cooling a space, believe it or not, also uses heat. In thermal dynamics, hot always moves towards cold, so we must remove the heat to cool a room. Contrary to what you might feel when you stand in front of the air conditioner, freezer, or fridge, we remove heat; we don’t add cold. Let’s break down how this works. You are standing inside a space, house, or container, and it’s hot, but you want to control the heat to become cooler. Well, the temperature outside the room is most likely the same or close, but you benefit from a contained environment. Heat transfer allows you to administer a coil filled with liquid inside and outside the container. The fluid preferably has properties that will enable energy absorption and release at an appropriate rate. The liquid must be at a lower temperature than the space before moving outside to absorb heat. Here is where the “magic” (science) happens. Moving the heat, once absorbed, out won’t have any effect unless our liquid is at a higher temperature than the space outside the container. To increase the temperature rapidly at the moment between rooms, we apply resistance/friction by compressing the liquid. Compressing the fluid into a smaller area naturally and quickly increases heat even higher than it has already absorbed. It pushes it through the coil outside the space, releasing the heat to the now colder outside environment. On its return journey indoors, we have the opposite scenario; we need to drastically cool the liquid so that it can reabsorb more heat. We expand it via a valve allowing its temperature to radically reduce and absorb more heat energy from inside the container to be released outside. When you stand in front of the air conditioner, you feel the fan placed inside and out to increase the heat transfer rate across the coils.
This principle of heating and cooling is called the refrigeration cycle, and in its simplest form, it is our primary form of controlling heat and coolness, or comfort, within our homes. Other systems use similar basic strategies to keep us warm in the winter. A boiler heats water using a flame and passes the water through the house via pipes, baseboards, or radiators, allowing the heat to transfer into the spaces and return to the boiler to be reheated. A water heater stores the heated water in a tank so that it is readily available when we call for it. A furnace, similarly, uses a heat source to heat air instead and passes the air through ductwork throughout the home. A solar hot water collector uses the sun to heat liquid passed through tubing on the exterior of the house and passes it through the house. A fireplace burns a source, whether wood, coal, pellets, gas, or liquid, and heats a thermal mass (most commonly brick or stone) which then radiates its heat back into the space. Depending on the style of the fireplace, it will potentially use the air from inside the room to burn to cause a reduction in moisture but a high heat source. A Geothermal heat pump, the system moves a liquid through a series of pipes installed with the earth. The earth has the beautiful benefit of maintaining a consistent temperature all year long below a certain depth, depending on the region. A heat pump will then pass the liquid through the lower temperature of the earth during the summer and the higher temperature of the earth in the winter. This system provides the added benefit of giving your home a consistent temperature to start from all year. An air-source heat pump (also known as a mini-split, ductless, or multi-split unit) is the same system as a heat pump geothermal system without the in-ground piping and the same as an air conditioning unit with the added benefit of being able to reverse the direction of the flow of liquid and heating the interior space instead of cooing it. Electric heaters resist the flow of electrons/electricity in their wires to produce heat (note: this source can be an inefficient use of electricity, often creating dangerous scenarios when, but it can also be convenient as an easily installed heat source.)
Now, we understand heating & cooling; how about dry & wet conditions, and everything in between? Humidity plays an extraordinary role in our comfort; we have all known the dog days of summer where sweat is in extra supply or reaching for that glass of water while enjoying the fireplace because of how dehydrated it made you. Air conditioning has the added natural ability to balance relative humidity. When the heat transfers from the space, it carries vapor that condenses onto the cold coils, is collected, and is then discharged. Picture a can of Coke on a picnic bench mid-summer day, sweltering as the heat transfers through the aluminum into the soda; once the temperature of the soda reaches equilibrium with the outside air, condensation stops forming on the can. Comparatively, in a cooling unit, the humidity in the room will naturally decrease as long as the cooling effects of the refrigeration cycle are operable. Our homes (containers or spaces) are like a big Coke can, except that the walls are not made of thin aluminum. As the temperature inside the house is heated or cooled, heat will want to transfer through our walls, floors, ceilings, and roof, leaving behind condensation. Hold on, Will, we spend a lot of money on materials to keep water out. Well, there is no way around the need for water being in our air, and that same air with moisture is what makes us comfortable. Have you ever heard about disaster stories related to mold issues? More often than not, the mold is caused by the lack of proper wall ventilation, causing a ripe condition (dark and wet) for mold to grow. So yes, we go to great lengths and cost to ensure that water outside the home is directed and diverted away from the interior, and for good reasons, it allows us to manage the water inside the wall gracefully. Where the Coke can have a thin wall for water to accumulate on, our homes have thick walls where it can hide. Hence, as Architects, we refer to the “dew point” to calculate the probable location condensation at different times of year and weather conditions based on unique location climate to determine the best wall assembly and layering to prevent condensation in the wall from wreaking havoc. So the in-between becomes just as important as the heating and cooling; besides structure, windows, doors, plumbing, and electricity, we want to control the heat transfer, water penetration and condensation, and air leakage.
Air sealing, more recently becoming more standard in construction, provides a more efficient container when done proficiently with the addition of an air barrier, a layer that prevents both water and air from passing through, which will control where and how heat transfer/ air enters the home. Maintaining the atmosphere is essential to efficiency. When we add a heat recovery ventilation unit, it provides fresh air at a controlled location while having the added benefit of recapturing heat from the air we are expelling to heat the new air we are replacing. Recycled air saves great energy by reducing our heat source workload and maintaining more stable control of the overall air quality. Another critical component is the insulation we use within the walls of the container. We measure insulation by R-value or the resistance value per inch to retain, reflect, and resist the transfer of heat energy. Higher R-value per inch means better insulation value and less load on our heat source. Vapor Barriers repel water while allowing air to pass through, which helps remediate moisture in the walls and prevent the growth of unwanted mold, algae, or fungi. High-Density spray foam is a barrier against all three elements and works as an efficient air, vapor, and heat barrier. The continuity of these layers is often referred to in the industry as an “envelope.” For the recognizable understanding that an envelope contains contents. It is crucial that our architectural details, and the following construction of those details, provide a continuous envelope of all three, minimizing thermal bridging (penetrations of materials with lower R-values, i.e., a wood stud) and undermining the control of heat and transfer of elements.
So when we work together to choose systems and different applications of providing comfort, we manage the added benefit of understanding that the most comfortable environments are those containing the highest level of control over how and where heat, vaper, and the air enters. Creating cohesive systems integrated with passive strategies (as outlined in my article about energy-efficient homes) will offer the most significant opportunity for a successful relationship between you and your home.
