ASHRAE 90_1
Content
ANSI/ASHRAE/IESNA Standard 90.1-2004
ASHRAE’s Newest Commercial Building Standard Rocky Mountain Chapter Technical Conference May 18, 2007
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Western Mechanical Solutions, llc
Michael K. Fulton, P.E. BSME
2 Years as a General Contractor 3 Years as a Consulting Engineer 7 Years as a Sales Engineer 6 Years as a Sales Manager
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Standard 90.1-2004
Developed jointly by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) and the Illuminating Engineering Society of North America (IESNA) Developed under American National Standards Institute (ANSI) consensus guidelines
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Standard 90.1-2004
Developed with participation from many building and construction organizations including:
– American Institute of Architects (AIA) – Building Owners and Managers Association (BOMA) – North American Insulation Manufacturer’s Association (NAIMA) – Air-Conditioning and Refrigeration Institute (ARI) – Gas Appliance Manufacturers Association (GAMA)
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Predecessors to Standard 90.1-2004
Standard 90.1-1999
– The US DOE found ASHRAE Standard 90.1-1999 did save energy and states were required to adopt a code that met or exceeded the provisions of Standard 90.1-1999 as their commercial building code by July 15, 2004.
Standard 90.1-2001
– Used as the basis of the IECC – The US DOE did not issue a formal determination on this standard
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Mandatory, Enforceable Language
Standard 90.1-2004 is a code-intended standard. As such, it is written in unambiguous language intended to allow a code official to say “that complies” or “that doesn’t” There are no “shoulds”, “coulds” or “shall consider” phrases – just lots of “shalls”
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Based on Consistent Economic Criteria
While previous ASHRAE standards were based on professional judgment combined with analysis of energy and cost impacts, Standard 90.1-2004 is the most recent attempt to use consistent economic criteria as the basis for requirements.
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True Prescriptive Paths
Anyone who has ever tried to use the ACP tables in Standard 90.1-1989 knows that there is not a true prescriptive path for envelope in the older ASHRAE standards. One of the “code friendly” features of codes is that they do have a simple prescriptive path for all buildings.
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Renovations and Retrofits
ASHRAE Standards before Standard 90.11999 were more or less silent on the concept. All standards were designed for “new construction” but what does that mean? ASHRAE worked with BOMA on Chapter 4 to develop detailed rules for how Standard 90.12004 should be applied to renovations and retrofits.
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Minimally Conditioned Buildings
Buildings that are minimally conditioned or minimally used should not need as stringent energy requirements as buildings that are fully conditioned or fully used. Standard 90.1-1999 took a first step in dealing with minimally conditioned buildings in its’ semi-heated space envelope requirements, and these requirements are contained in Standard 90.1-2004
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Climate Zones
Standard 90.1-2004 uses climate zones developed for the the US on a county-bycountry basis and expressed in map form. The map is the same map used in recent versions of the IECC, and above code documents like ASHRAE’s Advanced Energy Design Guide for Small Office Buildings.
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Interpretations for Standard 90.1
Users Manual
– Provides much of the background
Formal Interpretations
– Formal written interpretations take time
Informal Interpretations
– Quick, informal answers to questions
Steve Ferguson - ASHRAE Assistant Manager of Standards (404) 636-8400
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Standard 90.1 – Present
Standard 90.1-2001 is the reference standard for the 2003 IECC Standard 90.1-2004 will be the reference standard for NFPA 5000 and the 2006 IECC Standard 90.1-2001’s Energy Cost Budget method (coupled with 90.1-2001 Addenda e, now 90.1-2004 Appendix G) is the basis for LEED energy points certification
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Standard 90.1-2004
A total of 32 addenda to Standard 90.1-2001 were processed to completion in time for inclusion in Standard 90.1-2004. See Informative Appendix F to Standard 90.12004 for details Addenda - 1 admin, 3 ECB, 7 lighting and power, 4 envelope, and 17 mechanical
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Standard 90.1 - 2007
Next version - 90.1-2007
– Still being developed under continuous maintenance – Addenda under public review
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Organization of Standard 90.1
1 2 3 4 Purpose Scope Definitions Administration and Enforcement 5 Building Envelope 6 Heating, Ventilating, and AirConditioning 7 Service Water Heating 8 Power 9 Lighting 10 Other Equipment 11 Energy Cost Budget Method 12 Normative References
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Section 6 - HVAC Compliance
Mandatory Provisions (6.4)
Prescriptive Path (6.5)
Energy Cost Budget (11)
Simplified Approach (6.3)
Compliance
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Simplified Approach Option
(Section 6.3) Limited to…
– buildings with 1 or 2 stories – buildings < 25,000ft2 – single-zone systems – air-cooled or evaporatively-cooled only – Outside air qty less than 3000 cfm at min
Simplified Approach
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Simplified Approach (cont’d)
Manual changeover or dual set-point thermostat Heat pump supplementary heat control No reheat or simultaneous heating and cooling for humidity control Time clocks (except hotel/motel…) Pipe and ductwork insulated “Ducted system to be air balanced to within 10% of design air flow rates” Interlocked thermostats to prevent simultaneous heating and cooling Closing exhaust dampers (design capacity > 300 cfm unless continuous operation) Optimum start controls (design supply air capacity > 10,000 cfm) 19
HVAC Mandatory Provisions
(Section 6.4) Overview
Mandatory Provisions
Mechanical Equipment Efficiency (Section 6.4.1) Load Calculations (Section 6.4.2) Controls (Section 6.4.3) HVAC System Construction and Insulation (Section 6.4.4) Completion Requirements (Section 6.7) Required in both Prescriptive and ECB compliance paths
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HVAC Mandatory Provisions
Mechanical Equipment Efficiency
(Section 6.4.1)
Table 6.8.1E – (note Tables A, B, D, F and G addenda supplement package for efficiencies) Combination systems to meet all requirements for appropriate space heating or cooling category Equipment covered
– – – – – – – Package air conditioners Heat pumps Chillers Packaged terminal room air conditioners Furnaces Boilers Heat rejection equipment
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HVAC Mandatory Provisions
Load Calculations
(Section 6.4.2) “…Determined in accordance with generally accepted engineering standards and handbooks acceptable to the adopting authority”
– Another difference from the 1989 standard should be noted. It allowed a load safety factor of 10%. To give designers latitude, for example when expansions are planned, there is no longer an oversizing restriction.
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HVAC Mandatory Provisions
Controls Overview (Section 6.4.3)
Zone Thermostatic controls (Section 6.4.3.1) Set Point Overlap Restrictions (Section 6.4.3.2) Off-Hour controls (Section 6.4.3.3) Ventilation System Controls (Section 6.4.3.4) Where dampers are required (Section 6.4.3.3.4) Heat Pump Auxiliary Heat Control (Section 6.4.3.4) Humidifier Preheat Controls (Section 6.4.3.5) Humidification and Dehumidification Controls (Section 6.4.3.6) Freeze Protection and Snow/Ice Melting Systems (Section 6.4.3.7) Ventilation Controls for High-Occupancy Areas (Section 6.4.3.8) Exceptions
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HVAC Mandatory Provisions/Controls
Dead Band (Section 6.4.3.1.2)
Thermostats must have a 5°F dead band Exceptions
– “Thermostats that require manual changeover between heating and cooling modes – Special occupancy or special applications where wide temperature ranges are not acceptable (such as retirement homes, process applications, data processing, museums, some areas of hospitals) and are approved by the authority having jurisdiction. Addendum
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HVAC Mandatory Provisions/Controls
Set Point Overlap Restriction
(Section 6.4.3.1.3) If limit switches, mechanical stops, or software programming for DDC systems are used
– means will be provided “to prevent the heating set point from exceeding the cooling set point minus any applicable proportional band”
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HVAC Mandatory Provisions/Controls
Off-Hour Controls (Section 6.4.3.3)
Systems with heating/cooling and fan 1 hp and above:
Shall have all of the following off-hour controls - automatic shutdown - setback controls - optimum start controls - shutoff damper controls - zone isolation
Exceptions, HVAC systems
– serving hotel/motel guestrooms – intended to operate continuously” – Less than 15,000 BTU/h with Manual on/off
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HVAC Mandatory Provisions/Controls
Automatic Shutdown
(Section 6.4.3.3.1)
Controls to operate on different time schedules for seven different day-types per week and retain programming and time setting during loss of power for at least 10 hrs OR
– occupant sensor, OR – manually-operated timer with maximum two hour duration, OR – interlocked to security system
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HVAC Mandatory Provisions/Controls
Setback Controls
(Section 6.4.3.3.2)
Applies when heating systems are located where heating design temperature is in Climate zone 2-8 and cooling systems located in zones 1b, 2b, and 3b.
– Colorado is in climate zones 5b, 6b and 7
“Heating set point adjustable down to 55°F Cooling set point adjustable up to 90°F or to prevent high space humidity levels” Exception – “Radiant floor and ceiling heating systems”
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HVAC Mandatory Provisions/Controls
Optimum Start Controls
(Section 6.4.3.3.3)
“Individual heating and cooling air distribution systems with
– total design supply air capacity > 10,000 cfm – served by one or more supply fans”
Control algorithm to at least “be a function of
– difference between space temperature and occupied setpoint and amount of time prior to scheduled occupancy”
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HVAC Mandatory Provisions/Controls
Zone Isolation (Section 6.4.3.3.4)
Each isolation area
– Maximum 25,000 ft2 zone on one floor – Ability to shut off airflow to isolation area – Automatic shutdown device – Central systems capable of stable operation for smallest isolation area
• Review low load operation of equipment at the lowest load of smallest isolation area
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HVAC Mandatory Provisions/Controls
Shutoff Damper Controls
(Section 6.4.3.3.3)
Motorized dampers for outdoor air supply and exhaust systems that will automatically shut when not in use “Ventilation outside air dampers to be capable of automatically shutting off during – preoccupancy building warm up, cool down, and setback (Except when ventilation reduces energy costs or when ventilation must be supplied to meet code requirements) Supply and exhaust dampers to have maximum leakage rate meeting Table 6.4.3.3.4 when tested in accordance with AMCA Standard 500”
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HVAC Mandatory Provisions/Controls
Shutoff Damper Controls - Exceptions (Section 6.4.3.3.3) Gravity dampers okay in buildings
– < 3 stories in height – any height in climate zones 1, 2 and 3 – Systems with design outside air intake or exhaust capacity 300 cfm or less
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HVAC Mandatory Provisions/Controls
Dampers (Section 6.4.3.3.4) Max leakage rate - Table 6.4.3.3.4 – Denver climate zone 5b
• 10 cfm/ft2 at 1” motorized • 20 cfm/ft2 at 1” non motorized • Exception non motorized dampers less than 24” in either dimension is 40 cfm/ft2
– Mountains climate zone 6b and 7 max leakage is 4 cfm/ft2 at 1”
• Non motorized not allowed
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HVAC Mandatory Provisions/Controls
Ventilation Fan Controls (Section 6.4.3.3.5)
Fans with motors greater than ¾ hp shall have automatic controls complying with Section 6.4.3.2.1 that are capable of shutting off fans when not required. Exception – HVAC systems intended to operate continuously.
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HVAC Mandatory Provisions/Controls
Stair and Shaft Vents
(Section 6.4.3.4.1) Motorized dampers
– can be “automatically closed during normal building operation – interlocked to open as required by fire and smoke detection systems”
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HVAC Mandatory Provisions/Controls
Gravity Hoods, Vents, and Ventilators (Section 6.4.3.3.2) “Motorized dampers to automatically shut when spaces served are not in use” Exceptions
– Gravity dampers okay in buildings
• < 3 stories in height • of any height in climate zones 1, 2, 3 • Unconditioned spaces
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HVAC Mandatory Provisions/Controls
Humidifier Preheat
(Section 6.4.3.5) “Automatic valve to shut off preheat when humidification isn’t required”
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HVAC Mandatory Provisions/Controls
Humidification and Dehumidification
(Section 6.4.3.6)
For zones served with both humidification and dehumidification capability, means (such as limit switches, mechanical stops, or, for DDC systems, software programming) shall be provided capable of preventing simultaneous operation of humidification and dehumidification equipment. Exceptions – desiccant systems – Zones where specific humidity levels are required, such as computer rooms, museums, and hospitals and approved by the authority having jurisdiction. Addendum
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HVAC Mandatory Provisions/Controls
Freeze Protection and Snow/Ice Melting Systems (Section 6.4.3.7) Automatic controls for
– Freeze protection systems
• “off when outside air temperatures > 40°F or when conditions of protected fluid will prevent freezing”
– Snow - and ice-melting systems
• “pavement temperature > 50°F and no precipitation is falling and outdoor temperature > 40°F”
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HVAC Mandatory Provisions/Controls
Ventilation Controls for High-Occupancy Areas (Revised Section 6.4.3.8)
Revised Section 6.4.3.8 as follows: 6.4.3.8 Ventilation Controls for High-Occupancy Areas. – Demand Control Ventilation (DCV) is required for spaces larger than 500 ft2 (50m2) and with a design occupancy for ventilation of greater than 40 people per 1000 ft2 (100 m2) of floor area and served by systems with one or more of the following: – a. an air-side economizer – b. automatic modulating control of the outdoor air damper, – or – c. a design outdoor airflow greater than 3000 CFM (1,400 L/s) Exceptions to 6.4.3.8: – Systems with energy recovery complying with 6.5.6.1. – Multiple-zone systems without direct-digital control of individual zones communicating with a central control panel. – System with a design outdoor airflow less than 1,200 CFM (600 L/s). – Spaces where the supply air flow rate minus any make up or outgoing transfer air requirement is less than 1,200 CFM (600 L/s).
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HVAC Mandatory Provisions
HVAC System Construction and Insulation Overview (Section 6.4.4)
General (Section 6.4.4.1.1) Duct and Plenum Insulation (Section 6.4.4.1.2) Piping Insulation (Section 6.4.4.1.3) Duct Sealing (Section 6.4.4.2.1) Duct Leakage Tests (Section 6.4.4.2.2)
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HVAC Mandatory Provisions
Insulation General (Section 6.4.4.1.1)
Insulation installed in accordance with industry accepted standards (appendix E) Insulation
– Protected from damage due to sunlight, moisture, equipment maintenance, and wind – Exposed to weather to be suitable for outdoor service – “Covering chilled water piping, refrigerant suction piping, or cooling ducts located outside the conditioned space shall include a vapor retardant located outside the insulation, all penetrations and joints of which to be sealed”
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HVAC Mandatory Provisions/HVAC Insulation
Duct and Plenum Insulation (Section 6.4.4.1.2)
All supply and return ducts and plenums to be insulated per Tables 6.8.2A and 6.8.2B Exceptions
– Factory-installed plenums, casings, or ductwork furnished as part of HVAC equipment – Ducts or plenums located in heated, semi-heated, or cooled spaces – For runouts < 10 ft in length to air terminals or air outlets, the R-value need not exceed R-3.5 – Backs of air outlets and outlet plenums exposed to unconditioned or indirectly conditioned spaces with face areas > 5 ft2 need not exceed R-2; those 5 ft2 or less need not be insulated
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HVAC Mandatory Provisions/HVAC Insulation
Duct Sealing
(Section 6.4.4.2.1) Table 6.4.4.2A min Duct Seal Level
– Seal level based on duct type (supply, exhaust, return) and duct location (outdoors, unconditioned spaces, conditioned spaces)
Table 6.4.2B Duct Seal Level
– lists sealing requirements based on seal level from Table 6.4.4.2A
Standard industry practice
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HVAC Mandatory Provisions/HVAC Insulation
Duct Leakage Tests
(Section 6.4.4.2.2) Designed > 3 in. w.c.
– Leak tested – Representative sections no less than 25% of the total installed duct area shall be tested – Ratings > 3 in. w.c. to be identified on drawings
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Permitted duct leakage
– Maximum permitted duct leakage
“Lmax = CLP0.65
Where Lmax = maximum permitted leakage in cfm/100 ft2 duct surface area”
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HVAC Mandatory Provisions/HVAC Insulation
Piping Insulation
(Section 6.4.4.1.3)
Table 6.8.3
– Minimum pipe insulation thickness based on fluid design operating temperature range, insulation conductivity, nominal pipe or tube size, and system type (Heating, SWH, Cooling)
Exceptions
– Factory-installed – Piping conveying fluids between 60o and 105o F. – Piping conveying fluids not heated or cooled where heat gain/loss won’t increase energy use – Pipe unions in heating systems (steam, steam condensate, and hot water)”
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HVAC Prescriptive Path/Economizers
Economizers (Section 6.5.1)
Air Economizers (Section 6.5.1.1) Water Economizers (Section 6.5.1.2) Integrated Economizer Control (Section 6.5.1.3) Economizer Heating System Impact (Section 6.5.1.4)
Prescriptive Path
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HVAC Prescriptive Path/Air Economizers
Economizers (Section 6.5.1)
“Each cooling system having a fan shall include either an air or water economizer” Exceptions:
– Based on cooling size – Table 6.5.1 • Climate zone 5b, 6b not req’d below 65,000 btu/h • Climate zone 7 not req’d below 135,000 btu/h ??? – non-particulate air treatment as required by 6.2.1 of ASHRAE Standard 62.1 (addendum) – more than 25% of air is to be humidified above 35o dew point – Condenser heat recovery required by 6.5.6.2 – Some residential – Spaces where there is no cooling load at 60 deg – Operation less than 20 hours per week – Supermarkets where economizer will put load on cases – If cooling efficiency exceeds Table 6.3.2
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HVAC Prescriptive Path/Air Economizers
Design Capacity (Section 6.5.1.1.1)
“System capable of modulating outdoor air and return air dampers to provide up to 100% of the design supply air quantity as outdoor air for cooling”
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HVAC Prescriptive Path/Air Economizers
Control Signal (Section 6.5.1.1.2)
“Dampers capable of being sequenced with the mechanical cooling equipment and shall not be controlled by only mixed air temperature” Exception
– “MA limit control in systems controlled from space temperature (such as singlezone systems)”
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HVAC Prescriptive Path/Air Economizers
High Limit Shutoff (Section 6.5.1.1.3)
Automatically reducing outdoor air intake to the design minimum outdoor air quantity when outdoor air intake will no longer reduce cooling energy usage” Control types for specific climates from Table 6.5.1.1.3A zones 5b, 6b, 7 - Fixed db, Diff db, Electronic Enthalpy, Diff Enthalpy, dewpoint and db temp – no fixed enthalpy type High limit settings from Table 6.5.1.1.3B
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HVAC Prescriptive Path/Air Economizers
Dampers (Section 6.5.1.1.4)
Return air and outside air dampers to meet the damper leakage specified in 6.4.3.3.4 Denver 10 CFM per square foot at 1”
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HVAC Prescriptive Path/Air Economizers
Relief of Excess Outdoor Air
(Section 6.5.1.1.5)
“Means to relieve excess outdoor air during economizer operation to prevent over pressurizing the building Outlet located to avoid recirculation into the building”
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HVAC Prescriptive Path/Water Economizers
Water Economizers
(Section 6.5.1.2)
Design Capacity:
– Provide 100% cooling capacity at outdoor temps of 50 db/45 wb
Exception:
– If dehumidification cannot be met at outdoor temps of 50/45, then you can use 45 db / 40 wb
Max press drop (6.5.1.2.2)
– Coils and other heat transfer shall be less than 15 ft or create a secondary loop to reduce press drop
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HVAC Prescriptive Path
Simultaneous Heating and Cooling Limitation (Section 6.5.2)
Zone controls shall be capable of operating in sequence, the supply of heating and cooling energy to the zone to prevent
– reheating, – recooling, – mixing, or – simultaneously supplying air previously heated or cooled
Hydronic system controls to prevent reheating or recooling of fluids Exceptions
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HVAC Prescriptive Path
Zone Controls - Exceptions
“Zones for which volume of air that is reheated, recooled, or mixed is no greater than the larger of the following – Volume of outside air to meet 6.2 of ASHRAE 6.2 for the zone (add) – 0.4 cfm/ft2 of zone conditioned floor area – 30% of zone design peak supply – 300 cfm for zones whose peak flow rate totals no more than 10% of the total fan system flow rate – Any higher rate that can be demonstrated to jurisdiction to reduce overall system annual energy usage by offsetting reheat/recool energy losses through a reduction in outdoor air intake for the system. (addendum) Zones where special pressurization relationships, cross-contamination requirements, or code-required minimum circulation rates are such that the variable air volume systems are impractical Zones where at least 75% of the energy for reheating or for providing warm air in mixing systems is provided from a site-recovered (including condenser heat) or site solar energy source”
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HVAC Prescriptive Path
Air System Design and Control
(Section 6.5.3)
HVAC systems with total fan system power > 5 hp to meet 6.5.3.1 and 6.5.3.2
– Fan Power Limitation – VAV Fan Control
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HVAC Prescriptive Path
Fan Power Limitation
(Section 6.5.3.1)
Table 6.5.3.1
– By supply air volume and allowable nameplate motor power (constant volume and variable volume) – Volume CV VAV – < 20k cfm 1.2hp/1000cfm 1.7 hp/1000cfm – >=20k cfm 1.1hp/1000cfm 1.5 hp/1000cfm
Allowable fan system power may be adjusted in certain situations
– Filters – Heat recovery – etc
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HVAC Prescriptive Path
Part-Load Fan Power Limitation
(Section 6.5.3.2.1)
Individual VAV fans with motors 15 hp or greater
– Driven by VFD – Fan shall be van axial with var pitch blades – “Have other controls and devices to result in fan motor demand of no more than 30% of design wattage at 50% of design air volume when static pressure set point = 1/3 of total design static pressure, based on manufacturer’s certified fan data”
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HVAC Prescriptive Path
Static Pressure Sensor Location
(Section 6.5.3.2.2)
Placed so controller set point is no greater than 1/3 the total design fan static pressure
– Except for digital control systems with zone reset capabilities where it may be at the fan discharge
If this results in the sensor being located downstream of major duct splits, install multiple sensors in each major branch
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HVAC Prescriptive Path
Set Point Reset
(Section 6.5.3.2.3) “For systems with direct digital control of individual zone boxes reporting to the central control panel
– Static pressure set point reset based on zone requiring the most pressure”
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HVAC Prescriptive Path
Hydronic System Design and Control (Section 6.5.4)
“HVAC hydronic systems with total pump system power > 10 hp shall meet 6.3.4.1 – 6.3.4.4”
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HVAC Prescriptive Path
Hydronic Variable Flow
(Section 6.5.4.1)
HVAC pumping systems that include control valves designed to modulate or step open and close as a function of load
– Designed for variable fluid flow – Capable of reducing flow rates to 50% or less of design flow rate
“Individual pumps serving variable flow systems with a pump head > 100 ft and motor > 50 hp
– Have controls and/or devices resulting in pump motor demand no more than 30% of design wattage at 50% of design water flow”
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HVAC Prescriptive Path
Hydronic Variable Flow – Exceptions
Systems where
– “Minimum flow is < minimum flow required by equipment manufacturer for proper operation of equipment served by the system”
• Chiller with poor water turn down
– Total pump system power no more than 75 hp
Systems that include no more than 3 control valves
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HVAC Prescriptive Path
Pump Isolation (Section 6.5.4.2)
If chilled water plant has more than one chiller or boiler plant has more than one boiler
– Provide for flow reduction when chiller or boiler is shut down
• Prevents mixing, wasting energy
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HVAC Prescriptive Path
Chilled and Hot Water Temperature Reset Controls (Section 6.5.4.3)
Affects systems with design capacity > 300,000 Btu/h
– “To include controls to automatically reset supply water temperatures by representative building loads (including return water temperature) or by outside air temperature”
Exceptions
– Would result in improper operation
• Watch interior constant loads
– Hydronic systems with variable flow
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HVAC Prescriptive Path
Heat Rejection Equipment
(Section 6.5.5)
“Applies to heat rejection equipment used in comfort cooling systems such as
– – – – air-cooled condensers open cooling towers closed-circuit cooling towers evaporative condensers
Exceptions
– Heat rejection devices included as an integral part of equipment listed devices whose energy usage is included in Tables 6.2.1A-6.2.1D”
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HVAC Prescriptive Path
Fan Speed Control (condenser)
(Section 6.5.5.2)
Each fan powered by a motor 7.5 hp or larger shall have
– capability to operate fan at 2/3 full speed or less – “controls to automatically change the fan speed to control the leaving fluid temperature or condensing temperature/pressure of the heat rejection device”
Exceptions
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Exceptions
Condenser fans serving multiple refrigerant circuits or flooded condensers Installations located in climate zones 1 and 2 1/3 of the fans on a multiple fan application speed controlled
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HVAC Prescriptive Path
Energy Recovery
(Section 6.5.6) Exhaust Air Energy Recovery (Section 6.5.6.1) Heat recovery for Service Water Heating (Section 6.5.6.2)
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HVAC Prescriptive Path
Exhaust Air Energy Recovery
(Section 6.5.6.1)
Fans systems over 5,000 cfm and minimum OA of 70% or greater of the design supply air quantity shall have an energy recovery system with at least 50% recovery effectiveness. 50% effectiveness means change in enthalpy of the OA supply equal to 50% of the difference between the outdoor air and return air at design conditions
– Hard to do with coil loops and heat pipes??? – Easier with wheels and plate hx
Bypass or control heat recovery for economizer operation Exceptions: Lots – labs, un-cooled spaces heated less than 60 deg, toxic, grease kitchen hoods, if 60% of OA heat is site recovered or solar, heating in climate zone 1-3, cooling in some climate zones (Colorado), others
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HVAC Prescriptive Path
Heat Recovery for Service Water Heating (Section 6.5.6.2)
Condenser heat recovery systems shall be installed for heating or preheating of service hot water provided all of the following are true:
– 24/7 operation – Heat rejection of water cooled system exceeds 6,000,000 BTU/h (typically 430 to 440 tons of cooling) – Design service water heating load exceeds 1,000,000 btu/h (less than 20 gpm on 100 deg rise)
Heat recovery shall be the smaller of:
– 60% of peak heat rejection (258 cooling tons) – Preheat service water to 85 deg
Exceptions
– If 30% of heat rejection for space heating – Facilities that provide 60% of their service water heating from site solar or site recovered energy
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HVAC Prescriptive Path
Kitchen Hoods (Exhaust)
(Section 6.5.7.1)
Hoods > 5000 cfm to be “provided with makeup air sized for at least 50% of exhaust air volume that is a) unheated or heated to no more than 60°F and b) uncooled or cooled without the use of mechanical cooling Exceptions
– Where hoods are used to exhaust ventilation air that would otherwise exfiltrate or be exhausted by other fan systems – Certified grease extractor hoods that require a face velocity no greater than 60 fpm”
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HVAC Prescriptive Path
Radiant Heating Systems
(Section 6.5.8) Required for unenclosed spaces except loading docks with air curtains “Radiant heating systems that are used as primary or supplemental enclosed space heating must be in conformance with the governing provisions of the standard”
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HVAC Prescriptive Path
Hot Gas Bypass Limitation
(Section 6.5.9)
Shall not use HGBP (including other evaporator pressure control systems) “unless system is designed with multiple steps of unloading or continuous capacity modulation” Limited to:
– 50% capacity 240,000 BTU/h and below – 25% capacity above 240,000 BTU/h
Exception
– “Unitary packaged systems with cooling capacities not greater than 90,000 Btu/h”
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HVAC Mandatory Provisions/Completion Req
Drawings
(Section 6.7.2) Record drawings of actual installation to building owner within 90 days of system acceptance and include, as a minimum
– “Location and performance data on each piece of equipment – General configuration of duct and pipe distribution system including sizes – Terminal air or water design flow rates”
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HVAC Mandatory Provisions/Completion Req
Manuals (Section 6.7.2.2)
Operating and maintenance manuals to building owner within 90 days of system acceptance
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HVAC Mandatory Provisions/Completion Req
System Balancing
(Section 6.7.2.3) Balance in accordance w/generally accepted engineering standards (Appendix E) Written report for conditioned zones > 5000 ft2
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HVAC Mandatory Provisions/Completion Req
Air System Balancing
(Section 6.7.2.3.2)
Minimize throttling losses first For fans with system power > 1 hp
– Adjust fan speed to meet design flow conditions
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HVAC Mandatory Provisions/Completion Req
Hydronic System Balancing
(Section 6.7.2.3.3)
Proportionately balanced to minimize throttling losses “Pump impeller trimmed or pump speed adjusted to meet design flow conditions” Exceptions
– “Pumps with pump motors 10 hp or less – When throttling results in < 5% of the nameplate hp draw, or 3 hp, whichever is greater, above that required if the impeller was trimmed”
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HVAC Mandatory Provisions/Completion Req
System Commissioning
(Section 6.7.2.4) “Control elements are calibrated, adjusted, and in proper working condition” > 50,000 ft2 conditioned area
– Except warehouses and semiheated spaces – Requires commissioning plan provided by the designer
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Addenda to 90.1 - 2004
ANSI/ASHRAE/IESNA Addenda a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, r, s, t, u, v, x, and ak Note that v replaced s – how do you keep up? ANSI/ASHRAE/IESNA Standard 90.1-2004 http://www.ashrae.org/doclib/20060815_200661121930_347.pdf Clarification on Modeling Baseline Service Hot Water Systems for modeling Updated references Revise Tables 6.8.1A and 6.8.1B to reflect the newly adopted DOE efficiency standards for single-phase air conditioners and heat pumps less than 65,000 Btu/h. Revise minimum efficiency standards for air-cooled air conditioners and heat pumps listed in Tables 6.8.1A and 6.8.1B as follows for heat pumps over 65,000 Btu/h.
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Addenda to 90.1 - 2004
Revise the exceptions to Sections 6.4.3.1.2 and 6.4.3.6: 6.4.3.1.2 Dead Band & 6.4.3.6 Humidification and Dehumidification Revise Table A2.3 to add U-Factors for Screw-Down Roofs with R-19 Insulation as follows: Revise 5.5.4.4 as follows: 5.5.4.4 Fenestration Solar Heat Gain Coefficient (SHGC). Changes to international Climatic Data Revise Section 6.4.3.8 as follows (I-P and SI units): 6.4.3.8 Ventilation Controls for High-Occupancy Areas. Revise Table 6.8.1F as follow (I-P units): TABLE 6.8.1F Gas- and Oil-Fired Boilers—Minimum Efficiency Requirements
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Addenda to 90.1 - 2004
6.4.1 Equipment Efficiencies, Verification, and Labeling Requirements – 6.4.1.4 Verification of Equipment Efficiencies. – TABLE 6.8.1G Requirements for Performance Heat Rejection Equipment
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ASHRAE’s Newest Commercial Building Standard Rocky Mountain Chapter Technical Conference May 18, 2007
1
Western Mechanical Solutions, llc
Michael K. Fulton, P.E. BSME
2 Years as a General Contractor 3 Years as a Consulting Engineer 7 Years as a Sales Engineer 6 Years as a Sales Manager
2
Standard 90.1-2004
Developed jointly by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) and the Illuminating Engineering Society of North America (IESNA) Developed under American National Standards Institute (ANSI) consensus guidelines
3
Standard 90.1-2004
Developed with participation from many building and construction organizations including:
– American Institute of Architects (AIA) – Building Owners and Managers Association (BOMA) – North American Insulation Manufacturer’s Association (NAIMA) – Air-Conditioning and Refrigeration Institute (ARI) – Gas Appliance Manufacturers Association (GAMA)
4
Predecessors to Standard 90.1-2004
Standard 90.1-1999
– The US DOE found ASHRAE Standard 90.1-1999 did save energy and states were required to adopt a code that met or exceeded the provisions of Standard 90.1-1999 as their commercial building code by July 15, 2004.
Standard 90.1-2001
– Used as the basis of the IECC – The US DOE did not issue a formal determination on this standard
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Mandatory, Enforceable Language
Standard 90.1-2004 is a code-intended standard. As such, it is written in unambiguous language intended to allow a code official to say “that complies” or “that doesn’t” There are no “shoulds”, “coulds” or “shall consider” phrases – just lots of “shalls”
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Based on Consistent Economic Criteria
While previous ASHRAE standards were based on professional judgment combined with analysis of energy and cost impacts, Standard 90.1-2004 is the most recent attempt to use consistent economic criteria as the basis for requirements.
7
True Prescriptive Paths
Anyone who has ever tried to use the ACP tables in Standard 90.1-1989 knows that there is not a true prescriptive path for envelope in the older ASHRAE standards. One of the “code friendly” features of codes is that they do have a simple prescriptive path for all buildings.
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Renovations and Retrofits
ASHRAE Standards before Standard 90.11999 were more or less silent on the concept. All standards were designed for “new construction” but what does that mean? ASHRAE worked with BOMA on Chapter 4 to develop detailed rules for how Standard 90.12004 should be applied to renovations and retrofits.
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Minimally Conditioned Buildings
Buildings that are minimally conditioned or minimally used should not need as stringent energy requirements as buildings that are fully conditioned or fully used. Standard 90.1-1999 took a first step in dealing with minimally conditioned buildings in its’ semi-heated space envelope requirements, and these requirements are contained in Standard 90.1-2004
10
Climate Zones
Standard 90.1-2004 uses climate zones developed for the the US on a county-bycountry basis and expressed in map form. The map is the same map used in recent versions of the IECC, and above code documents like ASHRAE’s Advanced Energy Design Guide for Small Office Buildings.
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Interpretations for Standard 90.1
Users Manual
– Provides much of the background
Formal Interpretations
– Formal written interpretations take time
Informal Interpretations
– Quick, informal answers to questions
Steve Ferguson - ASHRAE Assistant Manager of Standards (404) 636-8400
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Standard 90.1 – Present
Standard 90.1-2001 is the reference standard for the 2003 IECC Standard 90.1-2004 will be the reference standard for NFPA 5000 and the 2006 IECC Standard 90.1-2001’s Energy Cost Budget method (coupled with 90.1-2001 Addenda e, now 90.1-2004 Appendix G) is the basis for LEED energy points certification
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Standard 90.1-2004
A total of 32 addenda to Standard 90.1-2001 were processed to completion in time for inclusion in Standard 90.1-2004. See Informative Appendix F to Standard 90.12004 for details Addenda - 1 admin, 3 ECB, 7 lighting and power, 4 envelope, and 17 mechanical
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Standard 90.1 - 2007
Next version - 90.1-2007
– Still being developed under continuous maintenance – Addenda under public review
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Organization of Standard 90.1
1 2 3 4 Purpose Scope Definitions Administration and Enforcement 5 Building Envelope 6 Heating, Ventilating, and AirConditioning 7 Service Water Heating 8 Power 9 Lighting 10 Other Equipment 11 Energy Cost Budget Method 12 Normative References
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Section 6 - HVAC Compliance
Mandatory Provisions (6.4)
Prescriptive Path (6.5)
Energy Cost Budget (11)
Simplified Approach (6.3)
Compliance
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Simplified Approach Option
(Section 6.3) Limited to…
– buildings with 1 or 2 stories – buildings < 25,000ft2 – single-zone systems – air-cooled or evaporatively-cooled only – Outside air qty less than 3000 cfm at min
Simplified Approach
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Simplified Approach (cont’d)
Manual changeover or dual set-point thermostat Heat pump supplementary heat control No reheat or simultaneous heating and cooling for humidity control Time clocks (except hotel/motel…) Pipe and ductwork insulated “Ducted system to be air balanced to within 10% of design air flow rates” Interlocked thermostats to prevent simultaneous heating and cooling Closing exhaust dampers (design capacity > 300 cfm unless continuous operation) Optimum start controls (design supply air capacity > 10,000 cfm) 19
HVAC Mandatory Provisions
(Section 6.4) Overview
Mandatory Provisions
Mechanical Equipment Efficiency (Section 6.4.1) Load Calculations (Section 6.4.2) Controls (Section 6.4.3) HVAC System Construction and Insulation (Section 6.4.4) Completion Requirements (Section 6.7) Required in both Prescriptive and ECB compliance paths
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HVAC Mandatory Provisions
Mechanical Equipment Efficiency
(Section 6.4.1)
Table 6.8.1E – (note Tables A, B, D, F and G addenda supplement package for efficiencies) Combination systems to meet all requirements for appropriate space heating or cooling category Equipment covered
– – – – – – – Package air conditioners Heat pumps Chillers Packaged terminal room air conditioners Furnaces Boilers Heat rejection equipment
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HVAC Mandatory Provisions
Load Calculations
(Section 6.4.2) “…Determined in accordance with generally accepted engineering standards and handbooks acceptable to the adopting authority”
– Another difference from the 1989 standard should be noted. It allowed a load safety factor of 10%. To give designers latitude, for example when expansions are planned, there is no longer an oversizing restriction.
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HVAC Mandatory Provisions
Controls Overview (Section 6.4.3)
Zone Thermostatic controls (Section 6.4.3.1) Set Point Overlap Restrictions (Section 6.4.3.2) Off-Hour controls (Section 6.4.3.3) Ventilation System Controls (Section 6.4.3.4) Where dampers are required (Section 6.4.3.3.4) Heat Pump Auxiliary Heat Control (Section 6.4.3.4) Humidifier Preheat Controls (Section 6.4.3.5) Humidification and Dehumidification Controls (Section 6.4.3.6) Freeze Protection and Snow/Ice Melting Systems (Section 6.4.3.7) Ventilation Controls for High-Occupancy Areas (Section 6.4.3.8) Exceptions
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HVAC Mandatory Provisions/Controls
Dead Band (Section 6.4.3.1.2)
Thermostats must have a 5°F dead band Exceptions
– “Thermostats that require manual changeover between heating and cooling modes – Special occupancy or special applications where wide temperature ranges are not acceptable (such as retirement homes, process applications, data processing, museums, some areas of hospitals) and are approved by the authority having jurisdiction. Addendum
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HVAC Mandatory Provisions/Controls
Set Point Overlap Restriction
(Section 6.4.3.1.3) If limit switches, mechanical stops, or software programming for DDC systems are used
– means will be provided “to prevent the heating set point from exceeding the cooling set point minus any applicable proportional band”
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HVAC Mandatory Provisions/Controls
Off-Hour Controls (Section 6.4.3.3)
Systems with heating/cooling and fan 1 hp and above:
Shall have all of the following off-hour controls - automatic shutdown - setback controls - optimum start controls - shutoff damper controls - zone isolation
Exceptions, HVAC systems
– serving hotel/motel guestrooms – intended to operate continuously” – Less than 15,000 BTU/h with Manual on/off
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HVAC Mandatory Provisions/Controls
Automatic Shutdown
(Section 6.4.3.3.1)
Controls to operate on different time schedules for seven different day-types per week and retain programming and time setting during loss of power for at least 10 hrs OR
– occupant sensor, OR – manually-operated timer with maximum two hour duration, OR – interlocked to security system
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HVAC Mandatory Provisions/Controls
Setback Controls
(Section 6.4.3.3.2)
Applies when heating systems are located where heating design temperature is in Climate zone 2-8 and cooling systems located in zones 1b, 2b, and 3b.
– Colorado is in climate zones 5b, 6b and 7
“Heating set point adjustable down to 55°F Cooling set point adjustable up to 90°F or to prevent high space humidity levels” Exception – “Radiant floor and ceiling heating systems”
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HVAC Mandatory Provisions/Controls
Optimum Start Controls
(Section 6.4.3.3.3)
“Individual heating and cooling air distribution systems with
– total design supply air capacity > 10,000 cfm – served by one or more supply fans”
Control algorithm to at least “be a function of
– difference between space temperature and occupied setpoint and amount of time prior to scheduled occupancy”
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HVAC Mandatory Provisions/Controls
Zone Isolation (Section 6.4.3.3.4)
Each isolation area
– Maximum 25,000 ft2 zone on one floor – Ability to shut off airflow to isolation area – Automatic shutdown device – Central systems capable of stable operation for smallest isolation area
• Review low load operation of equipment at the lowest load of smallest isolation area
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HVAC Mandatory Provisions/Controls
Shutoff Damper Controls
(Section 6.4.3.3.3)
Motorized dampers for outdoor air supply and exhaust systems that will automatically shut when not in use “Ventilation outside air dampers to be capable of automatically shutting off during – preoccupancy building warm up, cool down, and setback (Except when ventilation reduces energy costs or when ventilation must be supplied to meet code requirements) Supply and exhaust dampers to have maximum leakage rate meeting Table 6.4.3.3.4 when tested in accordance with AMCA Standard 500”
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HVAC Mandatory Provisions/Controls
Shutoff Damper Controls - Exceptions (Section 6.4.3.3.3) Gravity dampers okay in buildings
– < 3 stories in height – any height in climate zones 1, 2 and 3 – Systems with design outside air intake or exhaust capacity 300 cfm or less
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HVAC Mandatory Provisions/Controls
Dampers (Section 6.4.3.3.4) Max leakage rate - Table 6.4.3.3.4 – Denver climate zone 5b
• 10 cfm/ft2 at 1” motorized • 20 cfm/ft2 at 1” non motorized • Exception non motorized dampers less than 24” in either dimension is 40 cfm/ft2
– Mountains climate zone 6b and 7 max leakage is 4 cfm/ft2 at 1”
• Non motorized not allowed
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HVAC Mandatory Provisions/Controls
Ventilation Fan Controls (Section 6.4.3.3.5)
Fans with motors greater than ¾ hp shall have automatic controls complying with Section 6.4.3.2.1 that are capable of shutting off fans when not required. Exception – HVAC systems intended to operate continuously.
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HVAC Mandatory Provisions/Controls
Stair and Shaft Vents
(Section 6.4.3.4.1) Motorized dampers
– can be “automatically closed during normal building operation – interlocked to open as required by fire and smoke detection systems”
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HVAC Mandatory Provisions/Controls
Gravity Hoods, Vents, and Ventilators (Section 6.4.3.3.2) “Motorized dampers to automatically shut when spaces served are not in use” Exceptions
– Gravity dampers okay in buildings
• < 3 stories in height • of any height in climate zones 1, 2, 3 • Unconditioned spaces
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HVAC Mandatory Provisions/Controls
Humidifier Preheat
(Section 6.4.3.5) “Automatic valve to shut off preheat when humidification isn’t required”
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HVAC Mandatory Provisions/Controls
Humidification and Dehumidification
(Section 6.4.3.6)
For zones served with both humidification and dehumidification capability, means (such as limit switches, mechanical stops, or, for DDC systems, software programming) shall be provided capable of preventing simultaneous operation of humidification and dehumidification equipment. Exceptions – desiccant systems – Zones where specific humidity levels are required, such as computer rooms, museums, and hospitals and approved by the authority having jurisdiction. Addendum
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HVAC Mandatory Provisions/Controls
Freeze Protection and Snow/Ice Melting Systems (Section 6.4.3.7) Automatic controls for
– Freeze protection systems
• “off when outside air temperatures > 40°F or when conditions of protected fluid will prevent freezing”
– Snow - and ice-melting systems
• “pavement temperature > 50°F and no precipitation is falling and outdoor temperature > 40°F”
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HVAC Mandatory Provisions/Controls
Ventilation Controls for High-Occupancy Areas (Revised Section 6.4.3.8)
Revised Section 6.4.3.8 as follows: 6.4.3.8 Ventilation Controls for High-Occupancy Areas. – Demand Control Ventilation (DCV) is required for spaces larger than 500 ft2 (50m2) and with a design occupancy for ventilation of greater than 40 people per 1000 ft2 (100 m2) of floor area and served by systems with one or more of the following: – a. an air-side economizer – b. automatic modulating control of the outdoor air damper, – or – c. a design outdoor airflow greater than 3000 CFM (1,400 L/s) Exceptions to 6.4.3.8: – Systems with energy recovery complying with 6.5.6.1. – Multiple-zone systems without direct-digital control of individual zones communicating with a central control panel. – System with a design outdoor airflow less than 1,200 CFM (600 L/s). – Spaces where the supply air flow rate minus any make up or outgoing transfer air requirement is less than 1,200 CFM (600 L/s).
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HVAC Mandatory Provisions
HVAC System Construction and Insulation Overview (Section 6.4.4)
General (Section 6.4.4.1.1) Duct and Plenum Insulation (Section 6.4.4.1.2) Piping Insulation (Section 6.4.4.1.3) Duct Sealing (Section 6.4.4.2.1) Duct Leakage Tests (Section 6.4.4.2.2)
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HVAC Mandatory Provisions
Insulation General (Section 6.4.4.1.1)
Insulation installed in accordance with industry accepted standards (appendix E) Insulation
– Protected from damage due to sunlight, moisture, equipment maintenance, and wind – Exposed to weather to be suitable for outdoor service – “Covering chilled water piping, refrigerant suction piping, or cooling ducts located outside the conditioned space shall include a vapor retardant located outside the insulation, all penetrations and joints of which to be sealed”
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HVAC Mandatory Provisions/HVAC Insulation
Duct and Plenum Insulation (Section 6.4.4.1.2)
All supply and return ducts and plenums to be insulated per Tables 6.8.2A and 6.8.2B Exceptions
– Factory-installed plenums, casings, or ductwork furnished as part of HVAC equipment – Ducts or plenums located in heated, semi-heated, or cooled spaces – For runouts < 10 ft in length to air terminals or air outlets, the R-value need not exceed R-3.5 – Backs of air outlets and outlet plenums exposed to unconditioned or indirectly conditioned spaces with face areas > 5 ft2 need not exceed R-2; those 5 ft2 or less need not be insulated
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HVAC Mandatory Provisions/HVAC Insulation
Duct Sealing
(Section 6.4.4.2.1) Table 6.4.4.2A min Duct Seal Level
– Seal level based on duct type (supply, exhaust, return) and duct location (outdoors, unconditioned spaces, conditioned spaces)
Table 6.4.2B Duct Seal Level
– lists sealing requirements based on seal level from Table 6.4.4.2A
Standard industry practice
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HVAC Mandatory Provisions/HVAC Insulation
Duct Leakage Tests
(Section 6.4.4.2.2) Designed > 3 in. w.c.
– Leak tested – Representative sections no less than 25% of the total installed duct area shall be tested – Ratings > 3 in. w.c. to be identified on drawings
45
Permitted duct leakage
– Maximum permitted duct leakage
“Lmax = CLP0.65
Where Lmax = maximum permitted leakage in cfm/100 ft2 duct surface area”
46
HVAC Mandatory Provisions/HVAC Insulation
Piping Insulation
(Section 6.4.4.1.3)
Table 6.8.3
– Minimum pipe insulation thickness based on fluid design operating temperature range, insulation conductivity, nominal pipe or tube size, and system type (Heating, SWH, Cooling)
Exceptions
– Factory-installed – Piping conveying fluids between 60o and 105o F. – Piping conveying fluids not heated or cooled where heat gain/loss won’t increase energy use – Pipe unions in heating systems (steam, steam condensate, and hot water)”
47
HVAC Prescriptive Path/Economizers
Economizers (Section 6.5.1)
Air Economizers (Section 6.5.1.1) Water Economizers (Section 6.5.1.2) Integrated Economizer Control (Section 6.5.1.3) Economizer Heating System Impact (Section 6.5.1.4)
Prescriptive Path
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HVAC Prescriptive Path/Air Economizers
Economizers (Section 6.5.1)
“Each cooling system having a fan shall include either an air or water economizer” Exceptions:
– Based on cooling size – Table 6.5.1 • Climate zone 5b, 6b not req’d below 65,000 btu/h • Climate zone 7 not req’d below 135,000 btu/h ??? – non-particulate air treatment as required by 6.2.1 of ASHRAE Standard 62.1 (addendum) – more than 25% of air is to be humidified above 35o dew point – Condenser heat recovery required by 6.5.6.2 – Some residential – Spaces where there is no cooling load at 60 deg – Operation less than 20 hours per week – Supermarkets where economizer will put load on cases – If cooling efficiency exceeds Table 6.3.2
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HVAC Prescriptive Path/Air Economizers
Design Capacity (Section 6.5.1.1.1)
“System capable of modulating outdoor air and return air dampers to provide up to 100% of the design supply air quantity as outdoor air for cooling”
50
HVAC Prescriptive Path/Air Economizers
Control Signal (Section 6.5.1.1.2)
“Dampers capable of being sequenced with the mechanical cooling equipment and shall not be controlled by only mixed air temperature” Exception
– “MA limit control in systems controlled from space temperature (such as singlezone systems)”
51
HVAC Prescriptive Path/Air Economizers
High Limit Shutoff (Section 6.5.1.1.3)
Automatically reducing outdoor air intake to the design minimum outdoor air quantity when outdoor air intake will no longer reduce cooling energy usage” Control types for specific climates from Table 6.5.1.1.3A zones 5b, 6b, 7 - Fixed db, Diff db, Electronic Enthalpy, Diff Enthalpy, dewpoint and db temp – no fixed enthalpy type High limit settings from Table 6.5.1.1.3B
52
HVAC Prescriptive Path/Air Economizers
Dampers (Section 6.5.1.1.4)
Return air and outside air dampers to meet the damper leakage specified in 6.4.3.3.4 Denver 10 CFM per square foot at 1”
53
HVAC Prescriptive Path/Air Economizers
Relief of Excess Outdoor Air
(Section 6.5.1.1.5)
“Means to relieve excess outdoor air during economizer operation to prevent over pressurizing the building Outlet located to avoid recirculation into the building”
54
HVAC Prescriptive Path/Water Economizers
Water Economizers
(Section 6.5.1.2)
Design Capacity:
– Provide 100% cooling capacity at outdoor temps of 50 db/45 wb
Exception:
– If dehumidification cannot be met at outdoor temps of 50/45, then you can use 45 db / 40 wb
Max press drop (6.5.1.2.2)
– Coils and other heat transfer shall be less than 15 ft or create a secondary loop to reduce press drop
55
HVAC Prescriptive Path
Simultaneous Heating and Cooling Limitation (Section 6.5.2)
Zone controls shall be capable of operating in sequence, the supply of heating and cooling energy to the zone to prevent
– reheating, – recooling, – mixing, or – simultaneously supplying air previously heated or cooled
Hydronic system controls to prevent reheating or recooling of fluids Exceptions
56
HVAC Prescriptive Path
Zone Controls - Exceptions
“Zones for which volume of air that is reheated, recooled, or mixed is no greater than the larger of the following – Volume of outside air to meet 6.2 of ASHRAE 6.2 for the zone (add) – 0.4 cfm/ft2 of zone conditioned floor area – 30% of zone design peak supply – 300 cfm for zones whose peak flow rate totals no more than 10% of the total fan system flow rate – Any higher rate that can be demonstrated to jurisdiction to reduce overall system annual energy usage by offsetting reheat/recool energy losses through a reduction in outdoor air intake for the system. (addendum) Zones where special pressurization relationships, cross-contamination requirements, or code-required minimum circulation rates are such that the variable air volume systems are impractical Zones where at least 75% of the energy for reheating or for providing warm air in mixing systems is provided from a site-recovered (including condenser heat) or site solar energy source”
57
HVAC Prescriptive Path
Air System Design and Control
(Section 6.5.3)
HVAC systems with total fan system power > 5 hp to meet 6.5.3.1 and 6.5.3.2
– Fan Power Limitation – VAV Fan Control
58
HVAC Prescriptive Path
Fan Power Limitation
(Section 6.5.3.1)
Table 6.5.3.1
– By supply air volume and allowable nameplate motor power (constant volume and variable volume) – Volume CV VAV – < 20k cfm 1.2hp/1000cfm 1.7 hp/1000cfm – >=20k cfm 1.1hp/1000cfm 1.5 hp/1000cfm
Allowable fan system power may be adjusted in certain situations
– Filters – Heat recovery – etc
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HVAC Prescriptive Path
Part-Load Fan Power Limitation
(Section 6.5.3.2.1)
Individual VAV fans with motors 15 hp or greater
– Driven by VFD – Fan shall be van axial with var pitch blades – “Have other controls and devices to result in fan motor demand of no more than 30% of design wattage at 50% of design air volume when static pressure set point = 1/3 of total design static pressure, based on manufacturer’s certified fan data”
60
HVAC Prescriptive Path
Static Pressure Sensor Location
(Section 6.5.3.2.2)
Placed so controller set point is no greater than 1/3 the total design fan static pressure
– Except for digital control systems with zone reset capabilities where it may be at the fan discharge
If this results in the sensor being located downstream of major duct splits, install multiple sensors in each major branch
61
HVAC Prescriptive Path
Set Point Reset
(Section 6.5.3.2.3) “For systems with direct digital control of individual zone boxes reporting to the central control panel
– Static pressure set point reset based on zone requiring the most pressure”
62
HVAC Prescriptive Path
Hydronic System Design and Control (Section 6.5.4)
“HVAC hydronic systems with total pump system power > 10 hp shall meet 6.3.4.1 – 6.3.4.4”
63
HVAC Prescriptive Path
Hydronic Variable Flow
(Section 6.5.4.1)
HVAC pumping systems that include control valves designed to modulate or step open and close as a function of load
– Designed for variable fluid flow – Capable of reducing flow rates to 50% or less of design flow rate
“Individual pumps serving variable flow systems with a pump head > 100 ft and motor > 50 hp
– Have controls and/or devices resulting in pump motor demand no more than 30% of design wattage at 50% of design water flow”
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HVAC Prescriptive Path
Hydronic Variable Flow – Exceptions
Systems where
– “Minimum flow is < minimum flow required by equipment manufacturer for proper operation of equipment served by the system”
• Chiller with poor water turn down
– Total pump system power no more than 75 hp
Systems that include no more than 3 control valves
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HVAC Prescriptive Path
Pump Isolation (Section 6.5.4.2)
If chilled water plant has more than one chiller or boiler plant has more than one boiler
– Provide for flow reduction when chiller or boiler is shut down
• Prevents mixing, wasting energy
66
HVAC Prescriptive Path
Chilled and Hot Water Temperature Reset Controls (Section 6.5.4.3)
Affects systems with design capacity > 300,000 Btu/h
– “To include controls to automatically reset supply water temperatures by representative building loads (including return water temperature) or by outside air temperature”
Exceptions
– Would result in improper operation
• Watch interior constant loads
– Hydronic systems with variable flow
67
HVAC Prescriptive Path
Heat Rejection Equipment
(Section 6.5.5)
“Applies to heat rejection equipment used in comfort cooling systems such as
– – – – air-cooled condensers open cooling towers closed-circuit cooling towers evaporative condensers
Exceptions
– Heat rejection devices included as an integral part of equipment listed devices whose energy usage is included in Tables 6.2.1A-6.2.1D”
68
HVAC Prescriptive Path
Fan Speed Control (condenser)
(Section 6.5.5.2)
Each fan powered by a motor 7.5 hp or larger shall have
– capability to operate fan at 2/3 full speed or less – “controls to automatically change the fan speed to control the leaving fluid temperature or condensing temperature/pressure of the heat rejection device”
Exceptions
69
Exceptions
Condenser fans serving multiple refrigerant circuits or flooded condensers Installations located in climate zones 1 and 2 1/3 of the fans on a multiple fan application speed controlled
70
HVAC Prescriptive Path
Energy Recovery
(Section 6.5.6) Exhaust Air Energy Recovery (Section 6.5.6.1) Heat recovery for Service Water Heating (Section 6.5.6.2)
71
HVAC Prescriptive Path
Exhaust Air Energy Recovery
(Section 6.5.6.1)
Fans systems over 5,000 cfm and minimum OA of 70% or greater of the design supply air quantity shall have an energy recovery system with at least 50% recovery effectiveness. 50% effectiveness means change in enthalpy of the OA supply equal to 50% of the difference between the outdoor air and return air at design conditions
– Hard to do with coil loops and heat pipes??? – Easier with wheels and plate hx
Bypass or control heat recovery for economizer operation Exceptions: Lots – labs, un-cooled spaces heated less than 60 deg, toxic, grease kitchen hoods, if 60% of OA heat is site recovered or solar, heating in climate zone 1-3, cooling in some climate zones (Colorado), others
72
HVAC Prescriptive Path
Heat Recovery for Service Water Heating (Section 6.5.6.2)
Condenser heat recovery systems shall be installed for heating or preheating of service hot water provided all of the following are true:
– 24/7 operation – Heat rejection of water cooled system exceeds 6,000,000 BTU/h (typically 430 to 440 tons of cooling) – Design service water heating load exceeds 1,000,000 btu/h (less than 20 gpm on 100 deg rise)
Heat recovery shall be the smaller of:
– 60% of peak heat rejection (258 cooling tons) – Preheat service water to 85 deg
Exceptions
– If 30% of heat rejection for space heating – Facilities that provide 60% of their service water heating from site solar or site recovered energy
73
HVAC Prescriptive Path
Kitchen Hoods (Exhaust)
(Section 6.5.7.1)
Hoods > 5000 cfm to be “provided with makeup air sized for at least 50% of exhaust air volume that is a) unheated or heated to no more than 60°F and b) uncooled or cooled without the use of mechanical cooling Exceptions
– Where hoods are used to exhaust ventilation air that would otherwise exfiltrate or be exhausted by other fan systems – Certified grease extractor hoods that require a face velocity no greater than 60 fpm”
74
HVAC Prescriptive Path
Radiant Heating Systems
(Section 6.5.8) Required for unenclosed spaces except loading docks with air curtains “Radiant heating systems that are used as primary or supplemental enclosed space heating must be in conformance with the governing provisions of the standard”
75
HVAC Prescriptive Path
Hot Gas Bypass Limitation
(Section 6.5.9)
Shall not use HGBP (including other evaporator pressure control systems) “unless system is designed with multiple steps of unloading or continuous capacity modulation” Limited to:
– 50% capacity 240,000 BTU/h and below – 25% capacity above 240,000 BTU/h
Exception
– “Unitary packaged systems with cooling capacities not greater than 90,000 Btu/h”
76
HVAC Mandatory Provisions/Completion Req
Drawings
(Section 6.7.2) Record drawings of actual installation to building owner within 90 days of system acceptance and include, as a minimum
– “Location and performance data on each piece of equipment – General configuration of duct and pipe distribution system including sizes – Terminal air or water design flow rates”
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HVAC Mandatory Provisions/Completion Req
Manuals (Section 6.7.2.2)
Operating and maintenance manuals to building owner within 90 days of system acceptance
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HVAC Mandatory Provisions/Completion Req
System Balancing
(Section 6.7.2.3) Balance in accordance w/generally accepted engineering standards (Appendix E) Written report for conditioned zones > 5000 ft2
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HVAC Mandatory Provisions/Completion Req
Air System Balancing
(Section 6.7.2.3.2)
Minimize throttling losses first For fans with system power > 1 hp
– Adjust fan speed to meet design flow conditions
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HVAC Mandatory Provisions/Completion Req
Hydronic System Balancing
(Section 6.7.2.3.3)
Proportionately balanced to minimize throttling losses “Pump impeller trimmed or pump speed adjusted to meet design flow conditions” Exceptions
– “Pumps with pump motors 10 hp or less – When throttling results in < 5% of the nameplate hp draw, or 3 hp, whichever is greater, above that required if the impeller was trimmed”
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HVAC Mandatory Provisions/Completion Req
System Commissioning
(Section 6.7.2.4) “Control elements are calibrated, adjusted, and in proper working condition” > 50,000 ft2 conditioned area
– Except warehouses and semiheated spaces – Requires commissioning plan provided by the designer
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Addenda to 90.1 - 2004
ANSI/ASHRAE/IESNA Addenda a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, r, s, t, u, v, x, and ak Note that v replaced s – how do you keep up? ANSI/ASHRAE/IESNA Standard 90.1-2004 http://www.ashrae.org/doclib/20060815_200661121930_347.pdf Clarification on Modeling Baseline Service Hot Water Systems for modeling Updated references Revise Tables 6.8.1A and 6.8.1B to reflect the newly adopted DOE efficiency standards for single-phase air conditioners and heat pumps less than 65,000 Btu/h. Revise minimum efficiency standards for air-cooled air conditioners and heat pumps listed in Tables 6.8.1A and 6.8.1B as follows for heat pumps over 65,000 Btu/h.
83
Addenda to 90.1 - 2004
Revise the exceptions to Sections 6.4.3.1.2 and 6.4.3.6: 6.4.3.1.2 Dead Band & 6.4.3.6 Humidification and Dehumidification Revise Table A2.3 to add U-Factors for Screw-Down Roofs with R-19 Insulation as follows: Revise 5.5.4.4 as follows: 5.5.4.4 Fenestration Solar Heat Gain Coefficient (SHGC). Changes to international Climatic Data Revise Section 6.4.3.8 as follows (I-P and SI units): 6.4.3.8 Ventilation Controls for High-Occupancy Areas. Revise Table 6.8.1F as follow (I-P units): TABLE 6.8.1F Gas- and Oil-Fired Boilers—Minimum Efficiency Requirements
84
Addenda to 90.1 - 2004
6.4.1 Equipment Efficiencies, Verification, and Labeling Requirements – 6.4.1.4 Verification of Equipment Efficiencies. – TABLE 6.8.1G Requirements for Performance Heat Rejection Equipment
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