Hosted by: Welcome!
Building Science Principles for Managing Moisture in Tight Buildings for Arlington County Workshop on Balancing Moisture, Ventilation and Energy Efficiency by Armin Rudd, ABT Systems, LLC (www.abtsystems.us)
Building Control Layers Water Air Thermal Vapor Arlington County Workshop, 2013-12-11 Balancing Moisture, Ventilation, and Energy Efficiency 3
Air Compartmentalization is Key in Multifamily Most moisture flow is by airflow. Need to control the airflow. Stack, Wind, and Mechanically Induced Airflow Source: Building Science Corp. Arlington County Workshop, 2013-12-11 Balancing Moisture, Ventilation, and Energy Efficiency 4
Stack Effect in Cold Weather Air leakage condensation at top stories NPP + Air flows out at top Air flows in at bottom Source: Building Science Corp. Arlington County Workshop, 2013-12-11 Balancing Moisture, Ventilation, and Energy Efficiency 5
Controlling Stack Effect by Compartmentalization of Floors, Elevator Shafts, Corridors, Stairs, Chutes, and Units Source: Building Science Corp. Arlington County Workshop, 2013-12-11 Balancing Moisture, Ventilation, and Energy Efficiency
Elevator Vestibule Floor to Ceiling Critical Sealing Unit-to-Unit and Unit-to-Corridor Source: Building Science Corp. Arlington County Workshop, 2013-12-11 Balancing Moisture, Ventilation, and Energy Efficiency
Fully adhered air barrier drainage plane and insulation Source: Building Science Corp. Arlington County Workshop, 2013-12-11 Balancing Moisture, Ventilation, and Energy Efficiency
Maximum Air Leakage Targets Air Barrier Metrics Material 0.02 l/s-m 2 @75 Pa Assembly 0.20 l/s-m 2 @75 Pa Enclosure 2.0 l/s-m 2 @75 Pa 0.30 cfm50/ft 2 surface area 1.5 l/s-m 2 @75 Pa 0.23 cfm50/ft 2 surface area 1.0 l/s-m 2 @75 Pa 0.15 cfm50/ft 2 surface area Arlington County Workshop, 2013-12-11 Balancing Moisture, Ventilation, and Energy Efficiency 9
Balanced Ventilation In Each Dwelling Unit HRV/ERV Central-fan-integrated Supply + Single-point Exhaust Source: Building Science Corp. Arlington County Workshop, 2013-12-11 Balancing Moisture, Ventilation, and Energy Efficiency 10
System engineering trade-offs Start with high-performance building enclosure Improves the more permanent features of a home which has longer-term sustainability benefits Bulk water management, low loss/gain glass, controlled air change, ducts inside conditioned space, pressure balancing Allows for reduced cooling system size Helps pay for the enclosure improvements More compact duct system lowers cost and helps get the ducts inside Makes overall building performance more predictable Gives confidence for right-sizing equipment No short-cycling: Better moisture removal, Higher average efficiency, Better spatial mixing Controlled ventilation instead of random infiltration Results in decreased energy consumption along with increased occupant comfort Arlington County Workshop, 2013-12-11 Balancing Moisture, Ventilation, and Energy Efficiency 11
Humidity control goals Comfort, and Indoor Air Quality Control indoor humidity year-around, just like we do temperature Durability and customer satisfaction Reduce builder risk and warranty/service costs Arlington County Workshop, 2013-12-11 Balancing Moisture, Ventilation, and Energy Efficiency 12
Humidity control challenges 1. In humid cooling climates, there will always be times of the year when there is little sensible cooling load to create thermostat demand but humidity remains high Cooling systems that modify fan speed and temperature set point based on humidity can help but are still limited in how much they can over-cool 2. More energy efficient homes have less sensible heat gain to drive thermostat demand but latent gain remains mostly the same Low heat gain windows Ducts in conditioned space More, and better-installed, insulation Less heat gain from appliances and lighting Arlington County Workshop, 2013-12-11 Balancing Moisture, Ventilation, and Energy Efficiency 13
Humidity control challenges, cont. 3. More energy efficient cooling equipment often has a higher evaporator coil temperature yielding less moisture removal Larger evaporator coil by manufacturer design, or upsized air handler unit or airflow by installer choice 4. Conventional over-sizing to cover for lack of confidence in building enclosure or conditioning system performance causes short-cycling yielding less moisture removal Arlington County Workshop, 2013-12-11 Balancing Moisture, Ventilation, and Energy Efficiency 14
Dewpoint Temperature (F) Monthly Average Outdoor Dewpoint Temperature 80 70 60 50 40 30 Miami Houston Cincinnati Boston Phoenix San Francisco 20 10 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Typical Indoor (humid climate) Tdb RH Tdp winter 72 40 46 spring 75 45 52 summer 77 50 57 fall 75 45 52 Arlington County Workshop, 2013-12-11 Balancing Moisture, Ventilation, and Energy Efficiency
Dew point Temperature (F) Monthly Average Outdoor Dew Point Temperature 80 70 60 50 40 Baltimore Wash DC Norfolk Richmond San Francisco Miami 30 20 10 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Arlington County Workshop, 2013-12-11 Balancing Moisture, Ventilation, and Energy Efficiency
Moisture load for cooling and dehumidification systems in humid climates (75 F/55% RH indoor, 75 F outdoor dewpt) Moisture Load (lb water/day) 0 10 20 30 40 50 60 70 80 90 100 110 120 0.25 ach infiltration 0.1 ach infiltration with 50 cfm ventilation Air exchange People Cooking Dishwashing Bathing Clothes washing Floor mopping Building envelope New const drying Source for Cooking through New construction drying: Natural Resources Canada Arlington County Workshop, 2013-12-11 Balancing Moisture, Ventilation, and Energy Efficiency
Internal Moisture Gains from Boualem Ouazia, NRC-CAN, Humidity Control in Houses ERV Technology 24 lb/day
Cooling load (W) Cooling load (Btu/h) Cooling Load for: 50 cfm OA, Tdb,in=75, Tdp,in=55, Tdp,out=75 1200 1000 800 600 400 200 0 Total Latent Sensible 80 85 90 95 100 105 4000 3500 3000 2500 2000 1500 1000 500 0 Outdoor air temperature (F) Arlington County Workshop, 2013-12-11 Balancing Moisture, Ventilation, and Energy Efficiency
Conventional Cooling System Dehumidification Enhancements 1. Lower Airflow (costs more but increases moisture removal) 2. Overcooling 400 cfm/ton normal cooling in non-humid climate 350 cfm/ton for normal cooling in humid climate 300 cfm/ton (down to 250 cfm/ton) for extra dehumidification Limit any overcooling to 2 o F below setpoint to avoid comfort complaints 3. Don t run on constant fan when the coil is wet 4. Disable fan overrun after the compressor stops Arlington County Workshop, 2013-12-11 Balancing Moisture, Ventilation, and Energy Efficiency 20
What is Supplemental Dehumidification? Moisture removal, supplemental to the cooling system, when there is no need for cooling. Arlington County Workshop, 2013-12-11 Balancing Moisture, Ventilation, and Energy Efficiency 21
When is it needed? Mostly when the house is floating between cooling and heating setpoints Spring/Fall swing seasons and summer shoulder months Summer nights and rainy periods Sensitive to internal moisture generation too High occupant density Lack of local exhaust use in kitchens and baths Cooking habits (open boiling water) Arlington County Workshop, 2013-12-11 Balancing Moisture, Ventilation, and Energy Efficiency 22
What is a good metric for determining the need? Hours above 60% relative humidity and Condensation on windows Arlington County Workshop, 2013-12-11 Balancing Moisture, Ventilation, and Energy Efficiency 23
Dehumidifier and ventilation duct in interior mechanical closet with louvered door Arlington County Workshop, 2013-12-11 Balancing Moisture, Ventilation, and Energy Efficiency
Ducted dehumidifier in conditioned space with living space control Arlington County Workshop, 2013-12-11 Balancing Moisture, Ventilation, and Energy Efficiency
Dehumidifier process Evaporator coil Condenser coil Fan Supply Air Dew Point Entering Air Return Air Leaving Air Supply Air Fan Dehumidifiers add the heat of condensation, compressor heat, and fan heat to the space. (Supply air is typically 105 to 115 F) Arlington County Workshop, 2013-12-11 Balancing Moisture, Ventilation, and Energy Efficiency 26
What about making the existing cooling or heat pump equipment also do the supplemental dehumidification? Goals: Provide year-around relative humidity control in highperformance (low-sensible gain) dwellings Without over-cooling the space At lower installed cost than the same efficiency heating and cooling system with an additional high efficiency dehumidifier By making standard DX cooling equipment switchable between normal cooling and dehumidification-only using condenser reheat Arlington County Workshop, 2013-12-11 Balancing Moisture, Ventilation, and Energy Efficiency 27
Central system with modulating hot gas reheat Evaporator coil Modulating hot gas reheat coil Fan Supply Air Dew Point Entering Air Return Air Leaving Air Supply Air Fan Modulate the hot gas reheat to achieve a space-neutral supply air temperature. Affordable Comfort Conference 3/28/2012 Baltimore T 1 T 2 28
High Performance Ventilation for Multi-Family Buildings - Case Studies - Galen Staengl, PE LEED BD&C Certified Passive House Consultant Principal Staengl Engineering
Ventilation System Design for Multi-Family Buildings Design Objectives 1. Maintain Healthy Indoor Environments Provide Fresh Air Dilute Air Contaminants Control Humidity in Ventilation Air and Building 2. Minimize Building Energy Consumption 3. Minimize Cost of System and Cost of Ownership The Best Strategies Vary Based on Factors Such as Building Height and Unit Size.
Governing Codes ASHRAE 62.1 Applies to Multi-Family 4 Stories and Greater Does Allow Natural Ventilation ASHRAE 62.2 Applies to Single Family and Multi-Family Up to 3 Stories Does Not Allow Natural Ventilation in Most Climates GOOD PRACTICE: Don t Rely on Natural Ventilation!
Centralized vs. Unit Level Ventilation Unit Level Ventilation Less Maintenance for Building Owner Can Be Cheaper Can Help to Avoid Stack Effect Issues Centralized Ventilation Multi-Family Economy-of-Scale Allows for Better Heat Recovery / Dehumidification Equipment Can Provide Better Energy Performance and Building Humidity Control Increased First Cost
Integrated vs. Dedicated Ventilation Integrated Ventilation Ventilation System Integrated with Unit HVAC Requires System Fan to Operate to Ventilate Dehumidification is Done by HVAC Unit
Integrated vs. Dedicated Ventilation Dedicated Ventilation Independent System for Ventilation Does Not Depend on Unit HVAC Dehumidification Can be Done at the Outdoor Unit
Benefits of Energy Recovery Reduces Heating and Cooling Loads by 15-30% Reduces Heating Energy by 20 35% Helps to Control Building Humidity Ventilation
The Crossings at 4 th and Preston BRW Architects
The Crossings at 4 th and Preston Low Income Housing 60 Unit Single Room Occupancy 3 Stories + Basement Mixed Use: R-2, B & A-2 Earthcraft Award Best Multi-Family 2012
The Crossings at 4 th and Preston Challenges / Opportunities 1. Small Unit Size Right Sizing Equipment Encourages Centralized System 2. Developer Owned Allows Recoup of Up Front Investment 3. Low Income Population Smoking in Units Occupied Much of The Time
The Crossings at 4 th and Preston Ventilation Strategy Building: Dedicated Outside Air Unit Pressurized Corridors / Building Units: Intermittent Exhaust Driven
The Crossings at 4 th and Preston Ventilation Strategy Pros: DOA Unit Controls Building Humidity Reduced Ductwork Cost Fresh, Neutral Air Available on Demand Cons: No Energy Recovery Good IAQ Relies on Occupant Behavior Corridor Pressurization Does Not Effectively Prevent Cigarette Smoke Migration
Crescent Square VIA Design Architects, PC
Crescent Square Low Income Housing 80 Unit Single Room Occupancy 4 Stories Mixed Use: R-2, B & A-2 Earthcraft (Pending)
Crescent Square Ventilation Strategy Building: Dedicated Outside Air Unit Energy Recovery Units: Continuous, Balanced Ventilation & Exhaust Ducted to Each Unit Intermittent Range Hood Exhaust
Crescent Square Ventilation Strategy Pros: ERV + Dehumidification Unit Control Building Humidity Energy Recovery Saves Energy Continuous Ventilation to Building Cons: Increased Cost of Ductwork
Crescent Square Built-Up DOA Unit Built-up Outdoor Air System with an ERV + Split A/C Unit. Cost Effective Outdoor Air Humidity Control
System Testing and Commissioning Build it Tight and Ventilate Right! Building Air Leakage Testing Duct Leakage Testing
Summary Built it Tight and Ventilate Right Best Ventilation Strategy Varies Based on Building and Unit Size Continuous Ventilation Preferred Dedicated Ventilation Has Many Advantages Air and Duct Sealing Important
Mechanical Systems From Design to Verification December 11 th, 2013
Mechanical Systems From Design to Verification MF Mechanical System Challenges Team Based Design Data Rocks! Verification EarthCraft Virginia
MF Mechanical System Challenges HVAC Heating, VENTILATION, and Air Conditioning Also expect dehumidification, operate quietly, efficiently, fit in small space, be CHEAP, and not require much maintenance Air Conditioners have dehumidification capabilities, but are not dehumidifiers EarthCraft Virginia
Equipment Sizing/Selection for High Performance MF Housing Load Calculations Bigger is not better High Performance = 1000 sqft/ton MF heating/cooling loads 6-18 kbtuh Part load conditions/need for variable capacity Ductwork sealed, insulated and within conditioned space EarthCraft Virginia
Ventilation Design for positive pressure or balanced in our climate zone Don t suck on buildings in our climate zone (negative pressure/exhaust systems) Tenant vs. owner paid EarthCraft Virginia
MF Dehumidification Change in Housing Humidification vs. Dehumidification Rough-in for dehumidification Wire to refrigerator circuit to prevent resident tampering EarthCraft Virginia
Team Based Design Owners and Maintenance staff must be at the table Don t value engineer out all of the project s value Moisture Management Plan Design for the project population EarthCraft Virginia
I predict that someday energy will be so important that we will measure it. Henry Gifford EarthCraft Virginia
LIHTC Housing Study Energy Impact Study EarthCraft Virginia
LIHTC Housing Study Energy Impact Study EarthCraft Virginia
Verification (to prove something is true or correct) Find Hole Fix Hole (or verify no Hole) Definition of a Hole: a : an opening through something : perforation <have a hole in my duct> b : an area where something is missing : gap: as (1) : a serious discrepancy : flaw, weakness <some holes in your logic regarding your ventilation strategy>
You don t have to be good at math Common Sense is your best friend
Change is hard I know, I know
Buildings are just like our bodies Intentional and Purposeful holes
Blower Door aka Hole Hunter Measure airtightness level of building/unit envelopes Fancy tape measure for air leakage Test (when?) Typically, at Final Before drywall is hung in certain scenarios Code Compliance EarthCraft Virginia
Duct Blaster Test airtightness of forced air duct systems Diagnose and demonstrate leakage problems Estimate efficiency loss Test (when?) Before drywall is hung Final inspection Code Compliance EarthCraft Virginia
Duct Tape! (Don t use on ducts)
Mastic! EarthCraft Virginia
Flow Capture Device Used to accurately measure air flow in all residential applications Positive Duct Supplies Negative Duct Return Bath Exhaust Ventilation EarthCraft Virginia
Unit / Bedroom Pressures Pressures must be in balance Main body of the unit is negatively pressurized Bedrooms are positively pressurized EarthCraft Virginia
Thank You Philip Agee Philip.Agee@EarthCraftVirginia.org Chris Conway Chris@ConwayGreenConstruction.com EarthCraft Virginia
Thanks to our sponsoring partners!
Originated in the Ship Building Industry Test Functionality. In 1940 s Quality Control Process introduced to Manufacturing, W. Edwards Deming Total Quality Management (TQM) redefined Quality, Rebuilt Japan s Industrial Sector. 1980 s it was recognized that Buildings have become more Sophisticated. Response by ASHRAE develop a Commissioning Standards for Mechanical & HVAC Systems - Guideline 1 in 1989 and Guideline 0 in 2006 to address TQM in the Building Construction Industry. The Process is broken into 14 Major Activities from Conceptual Design Phase and ending after the building is turned over to the Owner with Training on Facility Operations & Maintenance is confirmed complete. Building must be Designed Correctly in order to be Constructed Correctly!
.. DOES THE DESIGN REALLY MEET OUR GOALS? Most Industries have recognized the need for a Quality Management Process. Goal is to Reduce their Costs and deliver Superior Products to their customers. The Building Industry has been far less successful in implementing Quality Assurance Processes than other Industries, thus resulting in buildings which cost more to build and use more energy than they should! A U.S. Dept. of Commerce & Bureau of Labor Statistics study showed that while most industries showed significant productivity increases across the board, the building construction industry lost productivity over the same time period! Other industry studies have shown that more than 50% of the costs of construction could be wasted, which is due to many factors which began during design and snowballed throughout the construction process!
Studies have shown that if a Commissioning Group is hired during the Conceptual Design stage and the MEP Systems are Commissioned, the following project characteristics are typical: The number of design RFI s and project Change Orders are reduced by up to 90%. Over all Construction Costs are Reduced by some 10% to 30% on average per project. The greater the project complexity, the greater the savings potential available. Building Energy Use is Reduced by some 10% to 30% as compared to non commissioned facilities. Owner s have a more productive Operations & Maintenance staff better able to address issues.
Lessons Learned: Conceptual Design involvement may have helped circumvent certain MEP design & operational issues encountered. ( Low Ambient Kits for ACC s) MEP System verifications brought to light a number of installation issues which would have detrimental impact on the long term effective operation of said systems. (T stat Wiring & AHU Dip Switch Settings). Moisture issues also identified. Performance Evaluations did discover improperly operating HVAC equipment which contributed to the inefficient running of the Air Conditioning Systems. (Refrigerant Over Charging - Wrong Ductwork Flow) The process discovered the need for greater frequency of filter changing by Maintenance personnel. Additional staff training required to more effectively address HVAC operational issues that may be encountered?
Questions & Answers.
Q & A Panel Discussion