Mechanical Systems and Solar Energy Research

 Chapter 4 – Mechanical Systems

In this week’s chapter we discussed Mechanical Systems. From these systems we were able to identify renewable fuel sources and compare heating systems and cooling systems to other methods of heating and cooling. We also learned the importance of the commissioning of systems with which they are involved and were able to identify issues of human comfort with regard to HVAC. From this we were able to show how to apply LEED energy-efficiency credits to a project.

Sources of Fuel and Fuel Consideration

This chapter begins with discussing the various types of fuels systems, such as bioenergy, fossil fuels, coal, oil, natural gas, hydrogen, nuclear energy, renewables, wind, hydropower, solar, geothermal, PV arrays, fusion, and electric power. It was a little overwhelming, to say the least, to be presented with so much information about a wide range of fuel systems. However, after reading about each one it becomes clear why they are so important and what role each fuel system plays within home and building renovation(s). Starting with bioenergy, we learn it is an organic compound similar to corn, municipal waste, and wood. While it is a renewable resource, it requires added energy to produce, and this explains why prices for biodiesel from corn have risen. In addition, sustainability concerns have appeared in regard to the growing of the corn because if the intense reliance on petroleum-based fertilizers.

On the other hand, fossil fuels that include petroleum, coal, and natural gas are infinite in quantity. The take over 85% of the fuel for electricity in the U.S. alone. Unfortunately, they take millions of years to accumulate and in turn are associated with greenhouse gases. Another fuel source that take years to acquire is a naturally occurring fuel that is obtained through underground mining operation or strip mining. This is coal and, while it takes a lifetime to gather, it is closely related to pollution and greenhouse gases. Thankfully, programs are in the process of being created to capture these gases and make mining a safer job for miners. Another common element is hydrogen and these developers are seeking to reduce U.S. dependence on foreign oil. Due to the fact that hydrogen can be made from fossil fuels and renewable sources, like wind, geothermal and solar, and used for alternative-fuel vehicles, no emissions result from hydrogen-fueled transportation systems.

The type of fuel chosen is dependent upon a variety of concerns such as cost, availability, and environmental impact. Because it is believed that we have already reached the point where our consumption of oil is outpacing the speed at which we extract it from the earth, our availability oil is expected to decline from this point on.

Mechanical Systems and Human Comfort

All of these varying fuel sources directly impact our job as designers because they are used to power the multiple types of mechanical systems used within a building or home. HVAC (interior heating and air) systems are designed used to provide human comfort, but this level of comfort varies from culture to culture and from person to person. This environment is created and
adapted due to the result of numerous factors including temperature and humidity. A psychrometric chart is used to determine and relate the dew point, wet-bulb temperature, dry-bulb temperature, and relative humidity to what is generally accepted as most people’s comfort zone. Mechanical treatment of the air is what creates these interior comfort conditions, which rely heavily on heating and cooling and methods of heat transfer such as evaporation, radiation, convection, and conduction.

Heating and Cooling Systems

Heat is understood to come in three forms: latent, sensible, and radiant. Latent is a state change, like a solid to a liquid, whereas sensible is a measure using a thermometer. Radiant is a form of electromagnetic radiation. Due to the fact that we know energy can not destroyed, only change state, it is important to understand the amount of heat it takes to raise on pound of water on degree Fahrenheit – BTU. This helps us understand that there are two main media to transfer energy - air and water – and each heating system relies on both medias to transfer heat. Heating system are also divided into those that use water and those that use air. Certain hydronic systems (heating systems that use water) include boilers, radiators, forced air, furnaces, electric resistance, and wood systems. Certain geothermal sources (heating systems that use air) include ground loop heat-pump systems, surface-water heat-pump systems, groundwater heat-pump systems, and hybrid geothermal sources. Typically geothermal sources are either closed loop or open loop.

Cooling, on the other hand, can be distributed in space in three ways: by avoiding heat gain, by passive cooling strategies, and by mechanical cooling. There are also a few different types of cooling systems that include central station systems, split systems, packaged units, and through-wall systems. A split system is typically used in smaller buildings and consists of both the compressor and condenser coil outside of the unit, and the evaporator coil and air handler are inside. A packaged unit is usually located on the roof, one unit for each zone, and provides air ti the interior spaces through multiple ducts. Through-wall units have the evaporator coil and fan on the inside with the condenser coil, fan, and compressor on the outside. These tend to service on room in a hotel or residential buildings.

Impacts on Interior Design

Although an interior designer doesn’t get involved with the actual design of the mechanical system, it is still a crucial concept for us to understand. Where the ducts, registers, and returns are integrated into the building effects the design of the interior space in ordinance with light fixtures, sprinkler heads, ceiling-mounted equipment – smoke detectors, projectors, etc. – and ceiling design details. Designers should also be aware of the location of the thermostat which is typically 44 to 48 inches above the finished floor because the space needed for mechanical equipment and HVAC mixing boxes are used to adjust the air and temperature going into the space, which in turn connects to the thermostat.

Solar Energy – Researched

Solar energy is created by the nuclear fusion that occurs in the sun and can be harvested for human uses. It is any type of energy acquired from the sun and solar panels are main way for humans to harvest this energy and convert it to electricity. This fusion occurs when hydrogen atoms collide in the sun’s core and create helium atoms. This process is known as a proton-proton chain reaction. This reaction releases VERY large amounts of energy in the form of waves and particles constantly flowing from the sun and through the solar system. Due to the fact that the usn does not shine 24/7 in most parts of the world, solar energy technologies include methods that store the energy during the nighttime. This energy is sent from photovoltaic systems to your local power grid or store energy in rechargeable batteries. A major advantage of this type of renewable energy sources is that it is renewable! It provides a steady, limitless supply for billions of years. A disadvantage, however, the cost of the equipment required to store and emit this energy into our homes and buildings.