Exam 2 - Heating & Cooling Loads and Ventilation

Why do we not use 100% OA

-Heating and cooling equipment size would be too big -Consumes a ton of energy

Conversion of Watts to BTUh

1 watts x 3.412 BTUh/Watts

What is the purpose of calculating heating/cooling loads?

1. Determine peak heating and cooling load 2. can be used to size and select equipment

Why should/do we use TRACE 700?

1. Makes our jobs easier 2. Helps us identify when we have peaks in loads

Heating and cooling load calculations depend on what elements?

1. Room Conditions 2. Occupancy 3. Building construction 4. Location

What are some benefits of using a template?

1. Save Time 2. Reduces the potential for errors 3. All standardized data is in there

An archived file has which of the following attributes:

1. Smaller File 2. Attaches all applied libraries

What factors affects human comfort?

1. Temperature 2. Humidity 3. Airspeed 4. Personal Parameters (Clothing, Metabolic rates)

What is the air speed in an occupied zone for heating?

30 fpm

What is the maximum head to foot temperature gradient?

3°F

What is the air speed in an occupied zone for cooling?

50 fpm

What air temperature should you maintain in the Winter?

68 - 75°F -Min 35% RH

What are the overall air temperature limits?

68°F - 80°F

What air temperature should you maintain in the Summer?

74 - 80°F @ 50% RH -Max 60% RH

What are the design standards for comfort index

75 Degrees, 50% RH

What columns are we using in the ASHRAE Weather Tables?

99.6% and 1%

What is a partition?

A partition is a wall that has heat gain or loss but is not an exterior wall (buried wall) Examples: Wall between a parking garage and office space Basement wall

When should misc. loads be added to your internal loads?

Any time there is a computer/office equipment Any time there are lights to be accounted for

When over 60% RH, what is the most common threat?

Black Mold

What does dilution do when ventilating?

Brings in OA that is cleaner than space air

What does CLTD stand for?

Cooling Load Temperature Difference

True or False: An energy model and a load calculation are the same things (the terms are interchangeable)

False

True or False: It is important to design a system for the worse case (extreme) weather conditions (heating and cooling) to ensure that the systems are not undersized when designing for human comfort.

False

True or False: Selecting a location under the weather tab close to that of the project is irrelevant since the values are being changed in the override function.

False

True or False: TRACE creates a 2D floor plan that can be printed.

False

True or False: TRACE is capable of conducting a load calculation but not an energy model

False

True or False: Templates are required on every project

False

True or False: Every building wall should be entered into TRACE 700

False Only walls that experience heat transfer should be modeled

What are potential sources for Cooling - Heat Gain?

Internal Envelope Solar

How does natural ventilation work?

It is the intentional air flow through doors, windows, vents, grilles, etc. by means of pressure differential

How does mechanical (forced) ventilation work?

It is the introduction of outside air through the use of fans

What does the F factor represent?

It is the thermal insulation of a slab/floor

What is infiltration?

It is unwanted/uncontrolled outside air that enters the building -typically through doors, cracks, and unintentional openings

What is the purpose of ventilation?

Move bad air out of the building so new air can enter. -Affects life, safety and welfare of the building occupant

What are the two types of ventilation allowed by code?

Natural Mechanical

Does it matter how you put in your Length and Width of your room dimensions?

No! Ex: 2x2 = 4, 4x1 = 4

When creating a custom wall how should you input your wall data?

Outside to Inside the wall

What situation would you care more about humidity design than temperature design?

Papermills

What are potential sources of Latent loads?

People Equipment

What are potential sources of Sensible loads?

People Equipment Envelope Lights

Why is over-sizing a system (especially cooling) a problem?

Requires more physical space More expensive system Decreased system efficiency Loss of humidity ratio Shorter equipment life

When should templates be used?

Should be used when there are multiple rooms with similarities

The thermostatic Set Point is determined by what ASHRAE standard?

Standard 55-2010

What table is used to find the F factor?

Table 6-20

What is Space Heat Gain?

The rate that heat enters a space

What is a cooling load?

The rate that heat must be removed to maintain set space conditions

T/F Selecting the 99.6% column for heating design applications in lieu of 99% column will result in a larger calculated load for an application.

True

True or False: The MCWB is the mean WB temperature that will occur at the same time as the designed DB.

True

True or False: The MCWB temperature is a lower value than the WB temperature for the same location.

True

True or False: When a wall library is created it is important that the components of the wall (material layers) be input in the order of construction.

True

T/F When selecting the design conditions for a building focused on human comfort the DB and MCWB should be used.

True: The MCWB should be used in lieu of the WB. Using the WB will result in condition that will not occur and an over sized system.

T/F Selecting the 0.4% column for cooling design applications in lieu of 2% column will result result in a larger calculated load for an application.

True: The 0.4% column will be the more conservative design (higher temperatures) and therefore will calculate a larger load for the system - bigger equipment.

Equation used to figure out ventilation in required based on space size and density of people

V = Rp*Pz+Ra*Az

What is ASHRAE Standard 62.1 used for?

Ventilation for Acceptable Indoor Air Quality

Where does heat loss comes from within the building?

Walls Floor Windows Roof

What is the heat loss equation for a wall/window/roof?

q = Area x U x (∆T)

What is the heat loss equation for a floor?

q = perimeter x F x (∆T)

Calculation for Internal Heat gain of lights

qs, lights= 3.412*W*(F_ul)*(F_sa)*N W=Wattage F_ul = Light Use factor F_sa = Light Allowance factor N= number of lights