providing insights for today’s hvac system designer Engineers Newsletter volume 47–2 HVAC-related changes in ASHRAE Standard 90.1-2016 down in a digital document (ironically 2013 version. This is the energy Jurisdictions have begun to adopt noted in this three-column document). ASHRAE 90.1-2013. We now look to the consumed by the entire building, 2016 version for ideas on how to save And due to overwhelming hue and cry, including equipment not regulated by energy over the 2013 version—for italics that were removed in the 2013 90.1. participating in above-code programs, version have been restored. Words in preparing for the future, or simply as a italics are defined in Chapter 3 of the The mechanical-related changes include: design preference for energy and energy cost saving. This Engineers Newsletter standard. You'll also find that digital • New climate zone assignments from describes important changes affecting versions have hyperlinks and cross- ASHRAE Standard 169-2013 HVAC systems and related equipment. references. There is also a new interactive tool for 90.1 available on the • Replacement equipment to follow some mandatory and prescriptive Since 1975, ANSI/ASHRAE/IES ASHRAE website. requirements (other than just Standard 90.1 (hereafter referred to as Purchase a copy of Standard 90.1, and efficiency) 90.1 for brevity) has been the basis of the accompanying User’s Manual to many energy codes, and continues to • New coverage in equipment classes better understand the requirements as be adopted directly or by reference in such as DOAS, CRAC and pool they apply to specific systems, climates, the International Energy Conservation dehumidifiers buildings and design applications. Code (IECC). It is also the basis for • Upgraded efficiency in packaged DX determining compliance with the rooftops, PTAC and VRF Energy Policy Act of 1992. • Economizer fault detection in While harmony is desired and 2016 HVAC Changes packaged DX equipment attempted between 90.1 and IECC, • Variable airflow exhaust- and return- some requirements diverge. This 121 addenda were incorporated in 2016. fan VFD control for building pressure newsletter identifies some of the areas Of those, only 23 had energy savings control and sections with the most differences which could be captured in any of the between the two model codes, to help nearly 600 energy models created by the • VFD threshold reductions (towers, designers select a preferred path when U.S. Department of Energy to determine pumps, fans) there is a choice. energy saving impacts. Some types of • Fan system control 5 hp threshold equipment are not used in any of the moved to subsections Look for this icon throughout this prototype buildings, some changed the newsletter to indicate significant optional performance path only, and • Chilled-water plant monitoring differences between 90.1-2016 and others simply added clarity to previous • 15°F minimum design delta T for IECC-2018. requirements. cooling coil selections The most obvious change is the new According to these models, the 23 • Chilled water reset alternative to formatting, which is better suited for addenda save 34 percent energy versus pump pressure reset digital use. More columns in the old the 2004 version, or 6.8 percent version lead to more scrolling up and (weighted average) compared to the Let's review these changes in more detail. ©2018 Trane. All rights reserved. 1 Revised climate classifications. Figure 1. ASHRAE climate zone map. ASHRAE 90.1-2016 updated to the climate classifications published in ASHRAE Standard 169-2013 (Figure1). The methods and data used to develop the classifications are sufficiently arcane that this newsletter will only summarize and illustrate the significance of this change. Some areas were quite affected (Figure 2). For example, 75 percent of the population of Wisconsin "moved" from climate 6A to 5A and 3 percent moved from 7 to 6A. Other states heavily reclassified are West Virginia (47%), North Carolina (43%), North Dakota (37%), Tennessee (36%), Indiana (30%) and Texas (24%). A few states reclassified as colder, such as Oklahoma (9% from 3A to 4A), New Hampshire (6% from 5A to 6A) and Washington (4% from 4C to 5C). Portions of 169 have been reprinted in the appendices of 90.1 for ease of reference. These changes have ripple effects Figure 2. Counties where climate zone classification has changed. throughout the Standard. For example, requirements for insulation, glazing, the economizer tradeoff and high limit controls may change, all with potential impacts on energy savings calculations. Climate zone 1 has been divided to include a new climate zone 0, to allow for more discerning requirements and their justifications for even hotter locations. Several areas outside of North America have begun to use 90.1 as the basis of their own energy RED counties moved to codes—some of which are in climate milder zones Source: zone 0. GREEN counties moved to colder zones 2 Trane Engineers Newsletter volume 47-2 providing insights for today’s HVAC system designer Mandatory Section (6.4) stringency. The table is quite large due to Prescriptive Section (6.5) Changes many different temperature conditions for Changes the various cooling and heating sources. Requirements in this section are Prescriptive requirements may be traded mandatory, meaning they cannot be Chiller-plant monitoring and reporting. off using one of the performance or traded off using any of the other Another mandatory requirement is for new alternative compliance paths. If you have a compliance paths. All paths include the chiller plants to have efficiency and energy situation where you can't or don't wish to mandatory sections. use measurement and reporting. This comply with a prescriptive requirement, requirement is invoked based on climate you may switch to the performance path and chiller-plant size (Table 1). Replacement equipment. Previously, (Chapter 11) or the new Energy-Cost- Budget (Appendix G) based compliance like-for-like replacement equipment only Table 1. Chiller-plant monitoring requirements had to meet the minimum efficiency option. requirements, and not all other Climate zone Water-cooled Air-cooled plant plant prescriptive and mandatory Replacement equipment requirements. In the new version, 3C,4C,5,6,7,8 >1500 tons >860 tons prescriptions. In addition to the replacement equipment is now obliged previously mentioned mandatory to also meet several mandatory (as well 0,1,2,3A,3B, >1000 tons >570 tons requirements, the following prescriptive as prescriptive) requirements. This 4A,4B requirements must also be met when includes off-hour controls, demand- replacing like-for-like equipment. controlled ventilation for single-zone • Economizers (outdoor units) systems, and setpoint controls. Other The data must be recorded and trended prescriptive requirements for every 15 minutes and graphically displayed • Integrated economizer control replacement equipment will be to include hourly, daily, monthly and annual • Economizer heating impact discussed later. information. The data must be maintained for at least three years. • Fan efficiency DOAS equipment. A new class of • Fan airflow control product has been added for direct- Economizer fault detection and • Ventilation optimization (multiple-zone expansion (DX), dedicated outdoor air diagnostics. This mandatory requirement VAV systems) systems (DOAS). This includes a applies to packaged unitary DX air- reference to the recently created AHRI conditioners and heat pumps, regardless of • Parallel, fan-powered VAV controls Standard 920, which reflects the condensing type, if they have an air • Fractional horsepower fan motors different conditions a 100 percent economizer. The purpose is to identify outdoor-air unit is expected to when sensors and controls on the • Fan speed control (heat rejection experience. The rating is based on equipment are not economizing (bringing in equipment) moisture removal efficiency (MRE) with more than minimum outdoor air) when • Chiller and boiler isolation an off-design rating of ISMRE for cooling outdoor conditions are favorable, or • Boiler turndown and/or ISCOP for heating. Standard 920 conversely if the economizer is active when and its use by 90.1 was the subject of a conditions are unfavorable. Permanent previous Engineers Newsletter. sensors, economizer status, fault Chilled-water reset. This is a new detection, reporting and provisions for test alternative to pump-pressure reset based Pool dehumidifiers and CRAC units modes are specified by 90.1. This on critical valve position. You may now are newly covered in the scope of requirement has been in place for several choose to reset chilled-water temperatures 90.1. The scope of 90.1 is written so years in California; manufacturers have to keep one valve nearly wide open or until that coverage for new equipment can be already developed equipment options that equipment limits are reached. Or, you may added over time. In this case, pool meet the requirements (Figure 3). continue to use pump-pressure reset dehumidifiers and CRAC units now have based on critical valve. Exceptions are minimum efficiency requirements. provided for district cooling, thermal Figure 3. Automatic fault detection implemented storage and process cooling. The Trane in a rooftop unit controller ENL in 2015 included a table comparing the VRF equipment. The 2013 version had energy performance of the two options. the first efficiency requirements for VRF Generally speaking, pump-pressure reset systems with a corresponding AHRI saves more energy at higher load (flow) certification program and test conditions, or when constant-speed procedure. The 2016 version changes chillers are used, and when system design some of the part-load requirements, delta T is less than 15º F. You can also effective either January of 2017 or 2018, choose to do both resets in sequence. That depending on the product. Part of this is is, do one until it reaches a limit and then due to a change in the test procedures the other. and part from an actual improvement in providing insights for today’s HVAC system designer Trane Engineers Newsletter volume 47–2 3 Table 2.