Dedicated Outdoor Air Systems: AHRI 920, ISMRE & ASHRAE 90.1

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1 Dedicated Outdoor Air Systems: AHRI 920, ISMRE & ASHRAE Peter Teige, Application Engineering Manager, AHRI Member Technical Training, October 12, 2016

2 AHRI 920: Establishes Efficiency Metric for DOAS Munters ISMRE: Highest in the industry ASHRAE Introduces Minimum ISMRE values. Munters exceeds by 2X! Overview 2

3 AHRI 920 Munters DryCool HCU & ERV units are Dedicated Outdoor Air Systems (DOAS) and are designed to deliver air at a room neutral temperature (typically degrees) and a low dew point (typically degrees dew point) and their primary purpose is to remove moisture from the ventilation air prior to its introduction into a conditioned space, and if the air is delivered below the required space dew point, it can also handle internal latent loads. DOAS are therefore primarily dehumidifiers, and as such, a new standard has been developed with a more appropriate and meaningful metric by which to measure their efficiency: AHRI 920 and Moisture Removal Efficiency (MRE). 3

4 4 MRE & ISMRE Efficiency Metric MRE is defined as pounds of moisture removed per kwh (lb/kwh). It is therefore a measure of the latent work done divided by total power input, as opposed to the more familiar efficiency metric in HVAC, Energy Efficiency Ratio (EER), which is a measure of the total (sensible + latent) work done divided by total power input. Similar to EER, MRE can be expressed in several different ways. An application MRE can be developed for a single unit and operating point, or the unit performance at four different conditions can be combined per the formulas in AHRI 920 to define a product's ISMRE, its Integrated Seasonal Moisture Removal Efficiency, similar to IEER. AHRI has recognized that single point efficiency ratings are not the best way to measure the efficiency of a product as it ignores part-load conditions, which are far more common than design conditions. Therefore, the primary metric to be used on this type of equipment for comparison is the ISMRE number.

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6 Munters Equipment MRE Munters has long promoted the DryCool process as more energy efficient for DOAS than the brute force cool-reheat process. The efficiency advantage can easily be shown on a psychrometric chart, plotting out the different paths these two processes take. The introduction of the MRE metric has allowed for this advantage to be quantified. Calculating the MRE values for Munters DryCool and brute force models has verified the 30-60% energy advantage on design day. Interestingly, the MRE value is very stable for a given piece of equipment and a given set of incoming conditions. So regardless of whether you are seeking a low supply dew point or a room neutral supply dew point, Munters energy advantage remains. DryCool equipment is not just for low dew points (although it does that!). DryCool is for anyone who wants industry leading DOAS efficiency for any DOAS application. Period. Munters performance and sales software, Munters Air Manager, has been calculating and reporting application MRE values for all HCU and ERV equipment since

7 MRE vs. Supply Dew Point MRE does not change versus supply air between 45 and 55 degrees dew point Munters DryCool technology most efficient regardless of supply dew point 95 F/78 F ambient: 50 ton brute force cool reheat system: 45, 50, 55 DP => MRE = ton HCU: 45, 50, 55 DP => MRE = 6.7 (60% less energy) 80 F/73 F part load: 50 ton overcool reheat system: 45, 50, 55 DP => MRE = ton HCU: 45, 50, 55 DP => MRE = 8.6 (60% less energy) 7

8 Humidity Ratio Grains of Moisture per Pound of Dry Air (gr/lb) Comparison of HCU vs. Cool-Reheat HCU doesn t need to cool to as low a temperature, so it saves significant energy over DX systems HCU Desiccant enhanced dehumidifier Cooling-Reheat dehumidifiers require 30% to 40% additional cooling to achieve same dew point Reheat F gr/lb Dry Bulb Temperature F 75 F 60 gr/lb

9 Humidity Ratio Grains of Moisture per Pound of Dry Air (gr/lb) Comparison of DryCool-ERV vs. Cool-Reheat HCU/ERV Desiccant enhanced dehumidifier mech cooling load Cooling-Reheat dehumidifiers require 30% to 60% additional cooling to achieve same dew point Energy Wheel Removes Significant Load on Design Days!! $$$ Reheat Dry Bulb Temperature F 75 F 60 gr/lb

10 Munters Equipment ISMRE Munters has calculated all values for ISMRE for all DryCool DX products. The ISMRE value is fixed for a given piece of equipment and is the best point of comparison for seasonal efficiency and cost to operate. As more manufacturers of DOAS equipment publish this information, it will become easier to compare specific models required for any given project and determine what the most energy efficiency choice is. Munters ISMRE calculations for each piece of equipment is shown on the following pages. Today, there is not much to compare these numbers against. Other manufacturer s equipment is really the only benchmark. There are no efficiency standards in place establishing requirements for this type of equipment. But we won t have to wait long. 10

11 Munters Calculated ISMRE for units without heat recovery Munters Model Number Airflow rate Ambient Temp Supply Conditions DB F WB F DB F WB F gr/lb DP F Electrical Power Input Suppleme ntary heat penalty Total Power Input MRC (lb/h) MRE (lb/kwh) ISMRE HCUc-2408AAD-BOB0000 2, HCUc-2408AAD-BOB0000 2, HCUc-2408AAD-BOB0000 2, HCUc-2408AAD-BOB0000 2, HCUc-3415AAD-BOB0000 3, HCUc-3415AAD-BOB0000 3, HCUc-3415AAD-BOB0000 3, HCUc-3415AAD-BOB0000 3, HCUc-4020AAD-BOB0000 4, HCUc-4020AAD-BOB0000 4, HCUc-4020AAD-BOB0000 4, HCUc-4020AAD-BOB0000 4, HCUc-6030AAD-BOB0000 5, HCUc-6030AAD-BOB0000 5, HCUc-6030AAD-BOB0000 5, HCUc-6030AAD-BOB0000 5, HCUc-6030AAD-BOB0000 6, HCUc-6030AAD-BOB0000 6, HCUc-6030AAD-BOB0000 6, HCUc-6030AAD-BOB0000 6,

12 Munters Calculated ISMRE for units without heat recovery (cont d) Munters Model Number Airflow rate Ambient Temp Supply Conditions DB F WB F DB F WB F gr/lb DP F Electrical Power Input Suppleme ntary heat penalty Total Power Input MRC (lb/h) MRE (lb/kwh) ISMRE HCUc-8040AAD-BOB0000 8, HCUc-8040AAD-BOB0000 8, HCUc-8040AAD-BOB0000 8, HCUc-8040AAD-BOB0000 8, HCUc-1250AAD-BOB , HCUc-1250AAD-BOB , HCUc-1250AAD-BOB , HCUc-1250AAD-BOB , HCUc-1260AAD-BOB , HCUc-1260AAD-BOB , HCUc-1260AAD-BOB , HCUc-1260AAD-BOB , HCUc-1680AAD-BOB , HCUc-1680AAD-BOB , HCUc-1680AAD-BOB , HCUc-1680AAD-BOB ,

13 Munters Calculated ISMRE for units with heat recovery Munters Model Number Airflow rate Ambient Temp Return Temp Supply Conditions DB F WB F DB F WB F DB F WB F gr/lb DP F Electrical Power Input Supplem entary heat penalty Total Power Input MRC lb/h MRE lb/kwh ISMRE ERVc-2508AAD-BBBS15M 2, ERVc-2508AAD-BBBS15M 2, ERVc-2508AAD-BBBS15M 2, ERVc-2508AAD-BBBS15M 2, ERVc-3010AAD-BBBS15M 3, ERVc-3010AAD-BBBS15M 3, ERVc-3010AAD-BBBS15M 3, ERVc-3010AAD-BBBS15M 3, ERVc-4012AAD-BBB0000 4, ERVc-4012AAD-BBB0000 4, ERVc-4012AAD-BBB0000 4, ERVc-4012AAD-BBB0000 4, ERVc-5416AAD-BBB0000 5, ERVc-5416AAD-BBB0000 5, ERVc-5416AAD-BBB0000 5, ERVc-5416AAD-BBB0000 5, ERVc-6018AAD-BBB0000 6, ERVc-6018AAD-BBB0000 6, ERVc-6018AAD-BBB0000 6, ERVc-6018AAD-BBB0000 6, ERVc-7020AAD-BBB0000 7, ERVc-7020AAD-BBB0000 7, ERVc-7020AAD-BBB0000 7, ERVc-7020AAD-BBB0000 7,

14 Munters Calculated ISMRE for units with heat recovery (cont d) Munters Model Number Airflow rate Ambient Temp Return Temp Supply Conditions DB F WB F DB F WB F DB F WB F gr/lb DP F Electrical Power Input Supplem entary heat penalty Total Power Input MRC lb/h MRE lb/kwh ISMRE ERVc-8024AAD-BBB0000 8, ERVc-8024AAD-BBB0000 8, ERVc-8024AAD-BBB0000 8, ERVc-8024AAD-BBB0000 8, ERVc-1026AAD-BBB , ERVc-1026AAD-BBB , ERVc-1026AAD-BBB , ERVc-1026AAD-BBB , ERVc-1230AAD-BBB , ERVc-1230AAD-BBB , ERVc-1230AAD-BBB , ERVc-1230AAD-BBB , ERVc-1440AAD-BBB , ERVc-1440AAD-BBB , ERVc-1440AAD-BBB , ERVc-1440AAD-BBB , ERVc-1648AAD-BBB , ERVc-1648AAD-BBB , ERVc-1648AAD-BBB , ERVc-1648AAD-BBB ,

15 ASHRAE 90.1, AHRI 920 & ISMRE DOAS equipment has been around for over 20 years and is installed in many buildings covered by ASHRAE However, the current standard has no minimum efficiency requirements for this type of equipment. The AHRI Dehumidification committee that wrote the 920 standard proposed to the ASHRAE 90.1 committee that this become a class of equipment covered by 90.1 and proposed minimum efficiency levels to be adopted. The AHRAE 90.1 committee approved the proposal and the public comment period has passed. The minimum ISMRE requirements for DOAS equipment will be added as an addendum to the 2013 version of 90.1 and will be included in the 2016 version to be released later this year. Comparing the minimum levels required by the standard, most Munters equipment is right around 2X as efficient as the standard requires!! 15

16 ASHRAE 90.1 Adoption Addendum XX

17 ASHRAE 90.1 Adoption Addendum XX

18 Munters ISMRE vs. ASHRAE 90.1 ISMRE Requirements ERVc Min HCUc Min No CFM ISMRE ISMRE CFM ISMRE ISMRE Avg Avg

19 Conclusion Munters DryCool equipment is the most energy efficient DOAS equipment on the market, whether you are looking for deep drying or room neutral dew point supply air. 19