Arch 537 - Prof. Strand (Part 2)

The only difference between a compression cycle chiller and a compression cycle heat pump is that a chiller will only cool water while a heat pump will only cool refrigerant.

False (CORRECT--the statement is FALSE. The only significant difference between a chiller and heat pump that both use a compression cycle is that generally speaking a chiller only provides COOLING while a heat pump can reverse its cycle to provide heating OR cooling.)

Which of the following are examples of components that are found in a compression cycle chiller? (Check ALL that apply.)

-evaporator -condenser -compressor -expansion valve (CORRECT! A compression cycle chiller includes FOUR components: condenser, expansion valve, evaporator, and compressor. The condenser is where the heat rejection to the outside environment occurs. The evaporator is where the cooling takes place. The compressor is where the refrigerant that is circulated between the components is compressed from a low pressure gas to a high pressure gas. In the compressor, as the gas pressure changes, so does the temperature of the refrigerant. Finally, the expansion valve is the flow control device in the chiller. All four components are necessary to complete the chiller compression cycle.)

What is approximately the percentage of all energy used in the USA that is consumed in all buildings?

40% (CORRECT! Approximately 40% of all energy used in the USA is consumed within the building industry. About half of that energy is consumed in commercial buildings and about half is consumed in residential buildings. Remember that around 40% of the energy consumed in buildings is used to maintain thermal comfort via HVAC system. This means that roughly 1/6 of all energy used in the USA is used by HVAC systems.)

According to ASHRAE, what percentage of the floor area of a building is taken up by MEP (mechanical, electrical, and plumbing)?

5-9% CORRECT! According to ASHRAE, MEP in a building takes up about 5-9% of floor area. While the electrical and plumbing space requirements are not trivial, the mechanical equipment in most buildings is the majority of the MEP space requirements because mechanical equipment tends to be very large in comparison.

Which of the following is a term that is commonly included in a heating load calculation?

A and B above. [Steady state heat loss through the building envelope.//Infiltration heat loss.] (CORRECT! A and B above (steady state heat loss through the building envelope and infiltration heat loss) are terms that are commonly included in a heating load calculation. In fact, those are the only two terms in a standard heating load calculation. The HVAC heating system is sized on this basis so that it has enough capacity to meet the building load even when there are no internal gains and there is no solar radiation present. In an office building, this mimics a very cold, cloudy day in winter on a weekend when no one is present.)

Which is of following are goals that we seek to achieve when sizing ducts?

A and C above [minimize duct size and travel//minimize pressure loss and noise] (CORRECT! Two goals that we have when sizing ducts is to minimize duct size and travel and minimize pressure loss and noise. In general, these two goals compete against each other since minimizing duct size and travel will result in smaller ducts that increase pressure loss and noise. Likewise, trying to minimize the pressure loss and noise will result in larger ducts that increase duct sizes. To properly size ducts, we have to find an acceptable middle ground between the two extremes.)

Which of the following is an assumption that is commonly made when performing a heating load calculation?

All of the above. [ Difficult case where the HVAC system has to handle all of the heating needs. // Constant indoor and outdoor temperatures.//No solar radiation.//No internal gains.] (CORRECT! All of the factors listed above are assumptions that are commonly made when performing a heating load calculation. The HVAC system is assumed to handle all of the heating need and so it is assumed that no internal gains and no solar gain is present to help the system. In addition, it is assumed that the inside and outside temperature remain constant. All of these assumptions actually make it possible to perform a reasonably accurate heating load hand calculation)

Building energy simulations are not effective in reducing energy consumption in buildings and are not applicable to compliance with ASHRAE Standard 90.1.

Correct--the statement is FALSE! Building energy simulations are highly effective in reducing energy consumption in buildings and can be used as part of the Energy Cost Budget (ECB) method as a path to compliance with ASHRAE Standard 90.1. Studies have shown and architectural/engineering firms have confirmed the importance of using building energy simulation and modeling as an integral part of the design process.

The type and location for the condenser of a compression cycle chiller does not affect performance and is purely a matter of convenience based on the building location and characteristics.

False (CORRECT--the statement is FALSE. The type/location of the condenser/condensing unit has a significant impact on the performance of a chiller. As the condenser temperature increases, the chiller becomes less efficient because it must raise the pressure and temperature of the refrigerant gas in the compressor more to get it above the outside temperature with which it has contact. Examples of condensing unit types include air cooled, water cooled, evaporative, and ground. Generally, air cooled condensers are convenient but the worst performers because they will interact with the highest temperature (outside dry bulb temperature) while ground condensers that are buried deep below the surface are the best performers.)

Building air exhausts can be placed near building fresh air intakes because air pressure from fans and wind prevent these two streams from interacting with each other.

False (Correct--the answer is FALSE! Building air exhausts should NOT be placed near building fresh air intakes because of the possibility that air from the exhaust will be drawn back into the building through the fresh air intakes. Neither air pressure from fans nor wind will prevent these two streams from interacting with each other.)

Building fresh air intakes can be placed anywhere on a building including near exhausts, kitchen and plumbing vents, loading docks, smoking areas, and cooling towers because fans create enough pressure to avoid any problems from these potential contaminants.

False (Correct--the answer is FALSE! Building fresh air intakes should NOT be placed near exhausts, kitchen and plumbing vents, loading docks, smoking areas, and cooling towers. All of these present potential contaminants that could get drawn into the building. This should be avoided as much as possible.)

When determining air distribution for tall spaces, where the spaces is actually occupied is irrelevant because the entire volume of the space must be conditioned.

False (Correct--the answer is FALSE! In tall spaces, it is critically important to determine how far up the space will be occupied. If the space is only occupied at the bottom, it is possible to condition only the occupied region down low and not be concerned about parts of the volume that won't ever be occupied. This can potentially save a significant portion of energy)

The options for vertical distribution of ducts in a building include along the circulation core, along the structure, along the edges, and in whole layers.

False (Correct--the answer is FALSE! While vertical distribution of ducts along the circulation core, along the structure, and along the edges of the building are viable options, whole layer distribution of air vertical through a building is not done and would be difficult to implement.)

The heat impact of infiltration is the same for both summer and winter conditions because the amount of infiltration stays the same from season to season.

False (Correct--the statement is false! Due to differences in temperatures in summer and winter as well as differences in the operation of the HVAC system, the expected ACH (air changes per hour) for infiltration varies significantly between summer and winter. Furthermore, the temperature difference between the inside and outside typically is very different as well. As a result, both the ACH and the total heat impact of infiltration will be vary greatly between the heating and cooling seasons. This means that we cannot use the same infiltration values for both heating and cooling calculations.)

HVAC equipment is never located in the basement or top floor of a building because of problems with access and equipment replacement.

False CORRECT--the statement is FALSE. The HVAC equipment of a building can be located in a variety of places including the basement, top floor, ground floor, or even a separate building. While placing the equipment in either a basement or top floor presents challenges to gaining access and replacing equipment, these issues can be overcome with careful planning and design.

ASHRAE Standard 62 recommends that the best means for providing for appropriate Indoor Air Quality (IAQ) is to provide a prescribed minimum amount of outside air and to filter air to remove contaminants.

True (Correct--the answer is TRUE! ASHRAE Standard 62 recommends that the best means for providing for appropriate Indoor Air Quality (IAQ). The two main things that ASHRAE Standard 62 recommends is to provide a prescribed minimum amount of outside air and to filter air to remove contaminants. The amount of outside air depends on both the type of space being addressed and the number of people in the space. In some cases, CO2 monitoring is done to better tailor the amount of outside air based on the actual number of people within a space.)

In underfloor air distribution, the supply plenum is created by raising the floor and using the space as a path for moving air from the air handler to the space.

True (Correct--the answer is TRUE! In underfloor air distribution, the floor of the space is raised up and the space underneath the floor is used as the supply plenum. The raised floor consists of large tiles that can be moved around as desired, making it easy to move a diffuser tile from one place to another and thus simplifying HVAC changes that are needed as a result of rearranging spaces.)

Sources of potential indoor air quality issues/problems in buildings include, but are not limited to, odors, VOCs, ozone, mineral fibers, asbestos, mold, fungi, bacteria, and radon.

True (Correct--the answer is TRUE! Odors, VOCs, ozone, mineral fibers, asbestos, mold, fungi, bacteria, and radon are all potential sources of indoor air quality problems in buildings. While some of these can be addressed by bringing fresh air into a building, others may require more significant mitigation solutions.)

Building energy simulation is a computer modeling process that can calculate both loads and energy consumption for a building.

True (Correct--the statement is TRUE! Building energy simulation programs use a variety of techniques to model the energy processes of a building using a computer. Typically, these calculations are done over longer periods of time like an entire year, making computers which are good at many, repetitive calculations ideal for doing these calculations. Building energy simulation programs are also able to perform load calculations and some use highly sophisticated algorithms to accurately estimate building performance.)

Lighting heat gain can be calculated using the "wattage" of individual fixtures and bulbs, but equipment heat gain cannot be calculated using the "nameplate" rating.

True (Correct--the statement is true! For lighting heat gain, we can simply add up the electrical rating or "wattage" for each fixture or bulb to come up with an estimate of the heat gain from lights. All of the electrical energy input into these bulbs will eventually get converted into sensible heat that will be added to the building. For equipment, the nameplate represents the maximum power draw that typically happens only for a very brief period of time when the device is turned on. After that, most equipment has a much lower average operating power consumption. So, using the nameplate rating would significantly overestimate the heat generated by equipment in a building.)

In the velocity method of duct sizing, the volumetric flow rate of air in the duct is divided by the maximum allowed velocity for the space type, duct location, and duct type to determine the cross-sectional area of the duct.

True (TRUE. In the velocity method, the cross-sectional area of the duct is the ratio of the volumetric flow rate of air in the duct to the maximum allowed velocity in the duct. The maximum allowed velocity is dependent on the type of space the duct is going through, the location of the duct with respect to space (exposed, behind a dropped ceiling, behind drywall), the shape of the duct (circular vs. rectangular), and whether the duct is a main, branch, or runout.)

A district heating and cooling system is a large scale centralized primary system that is used to produce chilled water and/or hot water/steam for more than one building or a group of buildings/campus.

True CORRECT--the statement is TRUE. A district heating and cooling system is a large scale centralized primary system that is used to produce chilled water and/or hot water/steam for more than one building or a group of buildings/campus. UIUC uses district heating and cooling to supply many buildings on campus with steam and chilled water. This simplifies building HVAC on campus because the buildings on campus that are part of the district heating and cooling system do NOT have to have a boiler or chiller.

A (thermal) load calculation is...

a snapshot in time that focuses on determining the size or capacity of various HVAC equipment under specific assumed conditions. (CORRECT! A load calculation is a snapshot in time that focuses on determining the size or capacity of various HVAC equipment under specific assumed conditions. This equipment might include, but is not limited to, ducts, fans, coils, pumps, chillers, boilers, heat pumps, etc.)

Sensible heat gain from people is dependent on the...

activity of people in the building. (CORRECT! Sensible heat gain from people is dependent on the activity of people in the building. In situations where people are more activity (like say a gymnasium), the average sensible heat gain experience by the space per person will also increase. Even when we are sleeping, we still generate some amount of heat. Clothing level is important for determining thermal comfort, but neither of these change significantly the amount of heat generated by people. Likewise, while natural ventilation and daylight improve indoor environmental quality (IEQ), they do not have any significant effect on the amount of heat generated by people.)

Internal Heat Gains...

add heat that must be removed by the cooling (HVAC) system and the most common ones are people, lights, and equipment. (CORRECT! Internal heat gains add heat that must be removed by the cooling (HVAC) system and the most common ones are people, lights, and equipment. In some building types, like office buildings, internal heat gains are the largest portion of the cooling load because of the high amounts of heat added by the presence of people, lights, and equipment.)

ACH is an abbreviation for...

air changes per hour. (CORRECT! ACH is an abbreviation for air changes per hour. Infiltration is caused by temperature differences, the stack effect, and potentially the operation of HVAC systems that circulate air. Note that purposeful flow of outside air through the building envelope such as opening windows is called ventilation.)

Which of the following are portions of the cooling load calculation?

all of the above [heat gains from infiltration//heat gains from internal loads like people, lights, and equipment] (CORRECT! All of the above are portions of the cooling load calculation outlined in class. In order to correctly calculated how much cooling we might need to do, we must figure out how much heat we gain from heat transfer through opaque building elements, solar and conduction heat gains through transparent building elements, heat gains from infiltration, and heat gains from internal heat sources like people, lights, and equipment. Neglecting any of these types of heat gain would run the risk of undersizing the HVAC cooling system, leading to uncomfortably warm temperatures on the interior of the building.)

Which of the following are assumptions that are commonly used when performing a cooling load calculation for buildings?

all of the above [variable outdoor air temperature//constant or setback indoor air temperature//presence of solar heat gains//presence of internal heat gains] (CORRECT! All of the above are assumptions that are commonly made for a cooling load calculation. As a result, the calculation for cooling loads has more terms and is generally more complicated than a heating load calculation.)

The term that refers to equipment that provides hot water or steam for various uses in the building is...

boiler CORRECT! A boiler is a device that provides hot water or steam for various uses in the building like HVAC needs. This hot water or steam is then used by secondary equipment to providing for heating needs within the building. Fuel boilers require both fuel and air (oxygen) for combustion to take place, and boilers are designed to try to maximize the heat transfer between the heat generated and the water being heated.

The term that refers to any disease caused by exposure to indoor contaminants and the effects of this exposure is felt long after exiting the building is...

building related illness (correct. Building Related Illness refers to any disease caused by exposure to indoor contaminants and the effects of this exposure is felt long after exiting the building. An example of building related illness is Legionnaire's Disease.)

The term that refers to selecting several smaller pieces of equipment rather than one very large device to improve building operation and efficiency is...

centralization correct. Redundancy is selecting several smaller pieces of equipment rather than one very large device. This is often done with primary equipment like boilers and chillers in buildings. The purpose of doing this is to improve building operation and efficiency. The one downside to doing this is that equipment will take up more space in the building.

The term that refers to a water/hydronic system that has chilled water coils that hang from the ceiling and provide cooling via active or passive movement of air to provide cooling is...

chilled beam system (CORRECT! A chilled beam is a water/hydronic system that has chilled water coils that hang from the ceiling and provide cooling via active or passive movement of air to provide cooling. In an active chilled beam, an air handler circulates air through the chilled beam system. In a passive chilled beam, warm air from the space rises to interact with the chilled beam where the cold surface of the coil cools the air, causing it to naturally drop to the occupied region of the space.)

The term that refers to a collection of equipment that provides chilled water or refrigerant for a secondary systems is...

chiller or heat pump CORRECT! A chiller or heat pump is a collection of equipment that provides chilled water or refrigerant for a secondary systems. Heat pumps can reverse their cycle to also provide heating during winter time. A chiller or heat pump that uses a compression cycle includes such components as a condenser, evaporator, compressor, and expansion value. These components are linked via a refrigerant that is circulated between the components to achieve cooling at the evaporator and heat rejection at the condenser.

The term that refers to a component that adds or removes heat and/or moisture in an air stream via energy exchange with a fluid circulating inside it is a...

coil. (CORRECT! A coil is a component that adds or removes heat and/or moisture in an air stream via energy exchange with a fluid circulating inside it. Coils come in a variety of types: cooling coils, heating coils, reheat coils, etc. While heating and reheat coils simply add heat to an air stream from hot water circulating inside it, a cooling coil can both remove heat and dehumidify the air stream if the surface temperature of the coil drops below the dewpoint temperature of the air.)

HVAC...

is all of the above. [stands for Heating, Ventilation, and Air-Conditioning//maintains comfort, controls humidity, and provides indoor air quality within a building.//has an impact on building energy consumption, space, noise, and maintenance of a building]

The secondary system of a building refers to the...

comfort delivery or space conditioning system including air, air-water, water/hydronic, and other system types. (CORRECT! Secondary system refers to the comfort delivery or space conditioning system of a building. In might include such equipment as an air-handler or other mechanical devices that provide direct conditioning to spaces. Types of secondary systems include air, air-water, water/hydronic, and other system types)

The term that refers to distributing some or all of the primary equipment and/or secondary HVAC equipment throughout the building is...

decentralization CORRECT! Decentralization of HVAC equipment refers to distributing some or all of the primary equipment and/or secondary HVAC equipment throughout the building. This is done more often on the secondary system side where air handlers are placed closer to the spaces that they are conditioning.

Which is of following terms refers to the thing that is the end point of the supply duct or starting point of a return duct?

diffuser (CORRECT! A diffuser is the end point of the supply duct or starting point of a return duct. Diffusers can be placed on ceilings, walls, or floors to distribute air into the space. A radial diffuser seeks to spread air out evenly in all directions while a slot diffuser is much more directional in nature as it seeks to introduce air in a particular direction into the space.)

The all-air secondary system type that is often used in museums and large assembly spaces and mixes air from a hot air supply duct with air from a cold air supply duct to provide very good control of both temperature and humidity is called a...

dual duct system. (CORRECT! A dual duct system is often used in museums and large assembly spaces because it provides very good control of both temperature and humidity. A duct duct system achieves this by mixing air from a hot air supply duct with air from a cold air supply duct to provide the correct supply air temperature. While the amount of air moving through each duct may vary, the total flow through both the hot and cold air supply ducts stays the same, meaning that this is a constant flow system.)

The term that refers to a pathway for HVAC air to move from one point of the building to another is...

duct. (CORRECT! A duct is a pathway for HVAC air to move from one point of the building to another. Supply ducts provide a pathway for air to move from the air handling unit in the mechanical room to conditioned spaces. Return ducts provide a pathway for air to move from conditioned spaces back to the air handling unit. Exhaust and outside air ducts help bring fresh air into the building to address indoor air quality issues.)

The primary system or central plant of a building refers to the...

energy conversion equipment that produces chilled water and either hot water or steam. (CORRECT! Primary systems or central plants are the energy conversion equipment that produces chilled water and either hot water or steam. Example of central plant equipment include boilers which produce either hot water or steam and chillers which produce chilled water for the building. In primary system equipment, a fuel source (electricity, natural gas, etc.) is used in various processes that then conditions water or some sort of glycol solution for use by the secondary system.)

Latent Heat Transfer is...

energy exchange associated with moisture (or phase) change. (CORRECT! Latent Heat Transfer is energy exchange associated with moisture (or phase) change. In buildings and HVAC systems, energy is required when moisture is added to or removed from air. Moisture being added to air requires evaporation of liquid water. Moisture removal from air requires condensation. Both of these require a phase change and this requires either an energy input or energy release. This is latent heat transfer.)

Sensible Heat Transfer is...

energy exchange associated with temperature change. (CORRECT! Sensible Heat Transfer is energy exchange associated with temperature change. All materials require some energy to change from one energy state or temperature to another. This energy is called sensible heat transfer. In buildings and HVAC system, we see many examples of sensible heat transfer. One such example is the temperature of the materials used to construction the building changing as conditions either inside the building or outside the building change.)

ASHRAE Standard 90.1 is the...

energy standard for buildings except low-rise residential buildings. (CORRECT! ASHRAE Standard 90.1 is the energy standard for buildings except low-rise residential buildings. It is often the basis for other energy standards such as federal government building standards, state and municipal standards, LEED, etc.)

The all-water secondary system type that is often used in hotels and hospitals and circulates water from a central source to a local conditioning unit is called a...

fan coil system. (CORRECT! A fan coil system is an air-water secondary system that is often used in hotels and hospitals because they allow for vastly different temperature settings for different spaces. It achieves this by conditioning water and piping that water to a local conditioning unit that has a thermostat in the room where the unit is located. This allows neighboring spaces to be at vastly different temperatures as one might encounter in hotel guest rooms)

The term that refers to the prime mover of HVAC air is...

fan. (CORRECT! A fan is a prime movers of HVAC air. The pressure provided by the fan moves the air through ducts throughout the building. There are both supply and return fans, both centrifugal and axial fans, and both fixed and variable speed fans that are used in building HVAC.)

The term that refers to a natural gas fired or electrically heated device that heats a space primarily through radiation directed toward a particular area is a/an...

high temperature radiant heating system. (CORRECT! A high temperature radiant heater is a natural gas fired or electrically heated device that heats a space primarily through radiation directed toward a particular area. High temperature radiant heaters often look like overhead hanging lights and are used to heat particular spots or areas within a space rather than the entire space. Most of the heat leaving these heaters is via radiation, and there is typically a reflective cover over the top of the heater to reflect energy back down to the occupied region of the space.)

The term that refers to air with no known contaminants at harmful levels and with which a substantial majority of people are not dissatisfied is...

indoor air quality (CORRECT! Indoor Air Quality (IAQ) refers to air with no known contaminants at harmful levels and with which a substantial majority of people are not dissatisfied. IAQ generally is dealt with according to ASHRAE Standard 62 by bringing in outside air and filtering supply air.)

The term that refers to a water/hydronic system that conditions or adjusts the temperature of a surface like a floor or ceiling in a space to provide radiation-based heating or cooling is a...

radiant heating system.

The term that refers to a fluid that is used to absorb heat/energy in one area and reject it in another is...

refrigerant CORRECT! A refrigerant is a fluid that is used to absorb heat/energy in one area and reject it in another. The chemical makeup and thermal properties of a refrigerant are important as they determine how efficiently energy can be transferred and how much compression is required to achieve the energy transfer required to run a particular cycle. The release of refrigerants that contain chlorine molecules is thought to be responsible for ozone depletion in the Earth's atmosphere as chlorine converts ozone (O3) back into oxygen (O2), and ozone has the ability to block certain harmful solar radiation but oxygen does not.

Convection is...

sensible heat transfer between a solid and a (moving) fluid. (CORRECT! Convection is sensible heat transfer between a solid and a (moving) fluid. There are two types of convection: natural/free or forced convection. Natural convection is a result of density differences in the fluid that arise as the fluid changes temperature. These density differences then cause the fluid to move. Forced convection results from a fluid being moved by some outside force such as wind, a fan, a pump, etc.)

Radiation is...

sensible heat transfer via electro-magnetic waves. (CORRECT! Radiation is sensible heat transfer via electro-magnetic waves. All objects emit and receive radiation even though we may not be able to physically see it. In general, we consider two main types of radiation in buildings--short wavelength radiation (visible light) and long wavelength radiation (infrared). Both impact the energy performance of a building.)

The term that refers to air-related acute discomfort complaints for at least 2 weeks from at least 20% of the occupants of a building whose symptoms end upon leaving the building is...

sick building syndrome (CORRECT! Sick Building Syndrome refers to air-related acute discomfort complaints for at least 2 weeks from at least 20% of the occupants of a building whose symptoms end upon leaving the building. Symptoms might include headache, fatigue, nausea, eye irritation, memory loss, respiratory irritation, etc.)

The prescriptive method for complying with ASHRAE Standard 90.1 is...

similar to a checklist approach with certain rules for various aspects of the building such as the envelope, the HVAC system, etc. (CORRECT! The prescriptive method for complying with ASHRAE Standard 90.1 is similar to a checklist approach with certain rules for various aspects of the building such as the envelope, the HVAC system, etc. The requirements of the standard, particularly in the area of building envelope, vary with the severity of the climate for the building location.)

Climate change is...

the general shift in the average annual global temperature. (CORRECT! Climate change is the general shift in the average annual global temperature. While many believe that this is due to human causes, particularly recent warming that has been experienced on earth, other see this as simply changes that occur due to natural phenomena.)

A thermal load is...

the heating or cooling required to balance other thermal forces at the thermostat setpoint temperature. (CORRECT! A thermal load is the heating or cooling required to balance other thermal forces at the thermostat setpoint temperature. These heating or cooling loads are essentially what the building HVAC has to provide to maintain comfort within the building as a result of various thermal forces on the building spaces.)

Ozone layer depletion is...

the loss of molecules of a particular gas in the atmosphere to avoid the increase in harmful levels of solar radiation. (CORRECT! Ozone layer depletion is the loss of molecules of a particular gas in the atmosphere to avoid the increase in harmful levels of solar radiation. "Conventional wisdom" states that the cause of the ozone layer depletion that was first noticed in the 1980s is that refrigerants that were not properly handled during HVAC system maintenance were allowed to escape into the atmosphere where the chlorine portion of certain refrigerant molecules would break ozone (O3) down into oxygen (O2). Since ozone blocks solar radiation of certain wavelengths but oxygen does not, the concern was that because these wavelengths of solar radiation were associated with skin cancer that this trend would lead to significant increases in skin cancer in humans if not addressed.)

Thermodynamics is...

the study of energy. (CORRECT! Thermodynamics is the study of energy. It seeks to understand a variety of thermal processes and quantify the impact that these processes have on their surroundings. In buildings, we study energy when we look at how the interior thermal conditions of a building change as a result of a variety of energy events, how an HVAC system meets various thermal needs, etc.)

Psychrometrics is...

the study of the mixture of (dry) air and water vapor. (CORRECT! Psychrometrics is the study of the mixture of (dry) air and water vapor. Psychrometrics helps us to characterize the conditions of "moist" air and is valuable for determining the amount of energy is needed to change the conditions of air from one state into another as is done in any HVAC system.)

Infiltration is...

the unintended flow of outside air into a building through leaks in the envelope, opening and closing of doors, etc. (CORRECT! Infiltration is the unintended flow of outside air into a building through leaks in the envelope, opening and closing of doors, etc. Infiltration is caused by temperature differences, the stack effect, and potentially the operation of HVAC systems that circulate air. Note that purposeful flow of outside air through the building envelope such as opening windows is called ventilation.)

Which of the following terms refers to a system that produces chilled water or ice during the nighttime and then uses it the next day to save on energy rates and reduce demand charges?

thermal energy storage CORRECT! Thermal Energy Storage is a system that produces chilled water or ice during the nighttime. This energy is stored and then used the next day. This takes advantage of cheaper night power rates to reduce the energy cost of the building. Also, because this will also reduce the peak demand of electricity during the day because the chiller is either not running or running at a reduced rate, there is also a potentially reduced demand charge that saves even more money. Chilled water storage systems can save both cost and energy but has a large footprint. An ice storage system is much smaller and save money, but due to the fact that the chiller must operate at a much lower temperature to produce ice, it may not save energy.

The all-water secondary system type that is similar to a fan coil system and tends to be used for mostly heating applications such as garages, warehouses, mechanical rooms, and greenhouses is called a...

unit heater/ventiltator system. (CORRECT! A unit heater or unit ventilator system is an air-water secondary system that is often used in garages, warehouses, mechanical rooms, and greenhouses. It can be similar to a fan coil system and tends to be used for mostly heating applications. Unit heaters are stand-alone heating elements that are often used to avoid freezing conditions while a unit ventilator often brings in outside air as part of its conditioning strategy.)

The all-air secondary system type that reduces flow to save conditioning needs and fan energy for many office buildings is called a...

variable air volume (VAV) system. (CORRECT! A variable air volume or VAV system is an all-air secondary system type that reduces flow to save conditioning needs and fan energy for many office buildings. Reducing the flow rate of air to a space to avoid overconditioning or reliance on reheating saves energy both by significantly reducing the need for a reheat coil and by significantly reducing the energy consumed by the fan. As a result, they are popular in office buildings because of their efficiency and because they work well when many spaces are generally controlled to roughly the same temperature.)