1. X472 HVAC System Design Considerations
Class 8 – Codes, Construction
Documentation and Coordination
Todd Gottshall, PE
Western Allied
Redwood City, CA
Reinhard Seidl, PE
Taylor Engineering
Alameda, CA
Fall 2015
Mark Hydeman, PE
Continual Energy, Inc.
mark.hydeman@continual.net
415-602-9982
www.continual.net
2. 2
General
Contact Information
Reinhard: rseidl@taylor-engineering.com
Mark: mark.hydeman@continual.net
Todd: tgottshall@westernallied.com
Text
• None
Slides
• download from web before class
• Log in to Box at https://app.box.com/login
• Username: x472student@gmail.com
• Password: x472_student (case sensitive)
3. 3
Course Outline
Date Class Topic Teacher
9/02/2015 1. Introduction / Systems Overview / walkthrough RS
9/09/2015 2. Generation Systems TG
9/16/2015 3. Distribution Systems RS
9/23/2015 4. Central Plants TG
9/30/2015 5. System Selection 1 - class exercises RS
10/07/2015 6. Specialty Building types (High rise, Lab, Hospital,
Data center)
TG
10/14/2015 7. System Selection 2 - class exercises RS
10/21/2015 8. Construction codes and Project delivery methods TG
10/28/2015 9. 2013 T24 and LEED v4 MH
11/04/2015 10. Life-Cycle Cost Analysis and exam hand-out TG
There are three instructors for this class. Todd Gottshall (TG), Reinhard Seidl (RS)
and Mark Hydeman (MH). The schedule below shows what topics will be covered by
who, and in what order.
4. 4
Outline
LCCA – Overview and Terminology
System Selection LCCA Example
Answers to Final
6. 6
Life-Cycle Cost Analysis
Evaluate economic performance over
entire life of a building.
• “Whole Cost Accounting”
• “Total Cost of Ownership”
Uses the “time value of money” to fairly
compare future costs with present costs.
7. 7
Life-Cycle Cost Analysis
Cannot compare Hp, Btu/h, tons, kW
directly, since it’s apples and oranges. But
can convert them all to the same units and
then compare
Same with money: as its value changes
over time, we cannot compare the actual
face values. But we can convert to present
value (PV) for a common denominator.
8. 8
Why LCCA Matters
Campus
Classroom /
Office
Building
Gates Computer Science Building
30 Year Life-Cycle Cost
Utilities,
$18,300,000, 28%
Maintenance,
$3,900,000, 6%
Service,
$2,400,000, 4%
System
Replacements,
$2,900,000, 4%
Initial Project Cost,
$37,700,000, 58%
9. 9
LCCA Possibilities
HEATING/COOLING SYSTEMS
• Central-plant connected vs. stand-alone systems
• Utility connection options if connected to the central plant
• Equipment options for stand-alone systems (e.g., chilled water vs. direct-expansion
(DX) units)
HVAC DISTRIBUTION SYSTEMS
• Air distribution systems (e.g., variable volume vs. constant volume, overhead vs.
underfloor)
• Water distribution systems (e.g., primary-only vs. primary-secondary)
BUILDING ENVELOPE
• Roofing systems (various materials and insulation methods)
• Glazing, daylighting, and shading options
SITING/MASSING
• Orientation, floor to floor height, and overall building height
• Landscape, irrigation, and hardscape options
10. 10
LCCA Possibilities
Generally for mechanical systems
• High first cost vs low energy/maintenance cost
• Low first cost vs higher energy or maintenance cost
• Balancing which of the two is better for overall customer needs is goal of LCC
0
2
4
6
8
10
12
14
Solution A Solution B
Which is better?
First Cost Energy Cost - 20 yrs
Solution ASolution B
FirstCost 5 8
Energy Cost- 20yrs 12 7.2
11. 11
Generally for mechanical systems
• High first cost vs low energy/maintenance cost
• Low first cost vs higher energy or maintenance cost
• Balancing which of the two is better for overall customer needs is goal of LCC
• Present potentially complex data sets in a simple comparison
LCCA Possibilities
Solution ASolution B
FirstCost 5 8
Energy Cost- 20yrs 12 7.2
0
2
4
6
8
10
12
14
16
18
Solution A Solution B
Which is better?
First Cost Energy Cost - 20 yrs
12. 12
When to do LCCA and how much
effort?
Complex analysis and significant effort when
• Potential first cost impact is high and potential operating
cost impact is high
• New or untested measures
• To prioritize competing or mutually exclusive energy
conservation efforts
Simple or no analysis when
• Payback is obvious based on past experience
• First cost impact is low
• Cost of complex analysis is a large % of cost of
measure
13. 13
LCCA Process
1. Establish Objectives
2. Determine LCCA Metrics and Criteria
3. Identify and Develop Alternatives
4. Gather Cost Information
5. Perform LCCA Calculations
16. 16
Time value of Money
Time-dependent value of money is much like
temperature-dependent air volume:
Which air handler supplies more air?
• 10,000 cfm
• 11,213 cfm
17. 17
Time value of Money
Time-dependent value of money is much like
temperature-dependent air volume:
Which air handler supplies more air?
• 10,000 cfm = 714 lbs/min @ 35°F, 80% RH (intake)
• 11,213 cfm = 714 lbs/min @ 95°F, 9.8% RH (supply)
• Same AHU, heating mode
18. 18
Time value of Money
Time-dependent value of money is much like
temperature-dependent relative humidity:
Which air handler supplies more humid air?
• 80%RH
• 9.8%RH
19. 19
Time value of Money
Time-dependent value of money is much like
temperature-dependent relative humidity:
Which air handler supplies more humid air?
• 80%RH = 29.8°F dewpoint at 35°F
• 9.8%RH = 29.8°F dewpoint at 95°F
Same AHU, heating mode
20. 20
Time value of Money
Asking “How much air” is like asking “How much
money”
• It depends on the psychrometric state of air
• It depends on the age of money
But we can make a common denominator
• Using mass to compare airflows
• Using present value (PV) or future value (FV), and compare
investments made at different times by comparing them “at
the same common time” by accounting for their ages
21. 21
Present Value
Accounts the “time value” of money.
Basic Discount Equation:
Where:
• PV is the present value (in Year 0 dollars)
• FY is the value in the future (in Year Y dollars)
• DISC is the discount rate
• Y is the number of years in the future
Y
Y
DISC
F
PV
)1(
22. 22
Escalation
Most items increase in price but do not track
overall inflation rate exactly.
Basic Escalation Equation:
Where:
• COSTYEAR-Y is the cost at Y years into the future
• COSTYEAR-0 is today’s cost (at Year 0)
• ESC is the escalation rate
• Y is the number of years into the future
Y
YEARYYEAR ESCCOSTCOST )1(0
23. 23
Study Life
Term of study over which costs will be
accumulated
Could be
• Life of equipment/system being analyzed
• Life of building
• As far into the future as you think you can
speculate
Typically, because of discount rate, does
not matter much to go beyond ~15 years
24. 24
LCCA Calculation Method
The formula for the basic LCC equation:
Where:
• LCC is the life cycle cost
• C is the Year 0 construction cost (hard and soft costs)
• PVRECURRING is the present value of all recurring costs
(utilities, maintenance, replacements, service, etc)
• PVRESIDUAL-VALUE is the present value of the residual
value at the end of the study life
VALUERESIDUALRECURRING PVPVCLCC
25. 25
LCC Discounted Payback Calculation
$0
$1,000,000
$2,000,000
$3,000,000
$4,000,000
$5,000,000
$6,000,000
$7,000,000
0 1 2 3 4 5 6 7 8 9 10
30 Year Study
CumulativeCost[PresentValue$]
300 6 12 18 24
payback in roughly 6 years
payback in roughly 9 years
EnergyAnalysisandLCCA
28. 28
Case Study:
UC Merced Classroom Building
90,000 sq. ft., 3 stories
Classrooms, Offices
Minimize energy use (20% below T-24)
– Heating and cooling
– Reheat
Maximize thermal comfort
Provide individual control
– Operable windows
– Integration with HVAC systems
LEED Rating
30. 30
What is Building Simulation?
Allows prediction of energy use, dynamic
response, control optimization
Options
• Custom spreadsheets
• Third party software
• Custom Visual Basic models
3rd Party Software
• EnergyPro (DOE-2.1)
• eQUEST (DOE-2.2, www.doe2.com)
• EnergyPlus
• TRACE
EnergyAnalysisandLCCA
31. 31
DOE-2 Inputs
Detailed Input Required!
Hourly Weather Data
Building Geometry
Glazing and Material
Properties
Internal Loads
HVAC Systems and
Equipment Efficiencies
Utility Rates and
Structures
EnergyAnalysisandLCCA
32. 32
DOE2 Outputs
500 pages text, 8 point font, minimum –
more depending on complexity and
reports
Hourly values for any variable of any
object
Predicts energy use
Predicts energy cost
EnergyAnalysisandLCCA
46. 46
Life-Cycle Cost Analysis Parameters
General Analysis Parameters
Study Life 30 years
Escalation Period 1 Ends in Year 5
General Inflation Rate 2.8%
Campus (Nominal) Discount Rate 6.5%
Real Discount Rate 3.6%
Annual Escalation Rates
Period 1: Years 1 to 5 Period 2: Years 6 to 30
Nominal Real Nominal Real
Maintenance 3% 0.22% 3.50% 0.71%
Materials 3% 0.22% 3.50% 0.71%
Natural Gas 5% 2.16% 4% 1.19%
Electricity 5% 2.16% 4% 1.19%
Electricity Rates
Summer Winter
(5/1 to 10/31) (11/1 to 4/30)
Demand Energy Demand Energy
[/kW] [/kWh] [/kW] [/kWh]
On-Peak* $16.00 $0.055 $10.75 $0.051
Off-Peak** $0 $0.037 $0 $0.033
* weekdays: 12:00 noon to 5:59 pm
** weekdays: 12:00 midnight to 11:59 am and 6:00 pm to 11:59 pm
** weekends: all day
Natural Gas Rates
Summer Winter
(5/1 to 10/31) (11/1 to 4/30)
[/therm] [/therm]
$0.590 $0.760
Chilled Water Rate
$5.06 /million Btu
Steam Rate
$7.20 /million Btu
Hot Water Rate
$3.60 /million Btu
Benefits to Campus Infrastructure
Peak Period
Utility Months Days Hours
CHW $1,000 /ton June-Sept M to F 3PM-6PM
CHW $100 /gpm June-Sept M to F 3PM-6PM
Steam $23 /pph Nov-Feb M to F 5AM-8AM
Electricity $300 /kW June-Sept M to F Noon-6PM
Hot Water $13 /MBH Nov-Feb M to F 5AM-8AM
Hot Water $100 /gpm Nov-Feb M to F 5AM-8AM
Discounted
Savings
47. 47
First Costs
Unmodified Modified
Maintenance First Cost Electricity First Cost
Run Description Cost Cost Peak Dist'n Peak Dist'n Peak Cost
[$] [$] [$] [$] [$] [$] [$] [$]
0 Base Case $7,658 $303,500 $303,500
1 Run Around Coil - w/o Evap $9,846 $364,025 -$46,000 -$4,416 -$1,406 -$244 $7,860 $319,819
2 Run Around Coil - w/ Evap $12,116 $378,725 -$58,083 -$5,576 -$1,406 -$244 $7,500 $320,916
3 Heat Pipe - w/o Evap $9,796 $378,025 -$55,750 -$5,352 -$1,610 -$280 $5,370 $320,403
4 Heat Pipe - w/ Evap $12,066 $392,725 -$70,699 -$6,787 -$1,610 -$280 $5,250 $318,599
5 Air-Air Plate HX - w/o Evap $9,796 $349,525 -$66,048 -$6,341 -$1,692 -$294 $3,300 $278,450
6 Indirect Evap Pre-Cooling $10,225 $351,500 -$63,429 -$6,089 -$1,166 -$203 $4,830 $285,443
Infrastructure Benefits
Chilled Water Hot Water
51. 51
Class Example
System 1: CRAC units
• First cost: $672,000
• Annual energy cost: $223,000
System 2: Central CHW plant and CRAHs
• First cost: $2,664,000
• Annual energy cost: $75,600
Energy cost escalation 4%
Depreciation 8%
Inflation 2%
No major replacement for either system
At what year does the central plant break even?