Building(Envelopes(and(Moisture(Control July 8, 2015

Transcription

1 Sustainable+Preservation+Practices+for+ Managing+Storage+Environments Series+#+3+8 Webinars Building(Envelopes(and(Moisture(Control July 8, 2015

2 Today s Presenter Jeremy Linden, Senior Preservation Environment Specialist, Image Permanence Institute Ably assisted by Christopher Cameron, Sustainable Preservation Specialist

3 Technical Support & Information Cable internet preferred rather than wireless or dial-up Participants can use their computer s speakers (VoIP) or telephone. United States Toll: +1 (646) Access Code: Audio PIN: Shown after joining the webinar Need Help? Contact Lauren Parish at lmppph@rit.edu or

4 Questions? Submit questions using the Question Box located in the Go To Webinar control panel.

5 Sustainable Preservation Practices for Managing Storage Environments The third series of workshops & webinars Funded by a National Endowment for the Humanities Education & Training Grant

6 Sustainability Series Presentations are Designed To Provide: A better understanding of how to balance the need to both preserve collections and reduce energy consumption Practical guidelines for managing/reducing any risk to collections that could result from new energy management practices

7 Today s Presentation Geared to historic buildings and small institutions primarily You have to balance the need to maintain the historic integrity of the building with the preservation of collections There are unique challenges when managing the environment of a historic building

8 Webinar 6 Building Envelopes & Moisture Control Today s Focus: Building Envelope Assessment Building Classification Overview Managing Heat & Moisture Loads Understand & Diagnose Problems & Risks Consequences of Seasonal Building Closure Strategies for Improvement Next Webinar August 12 th 2:00 PM EST Understanding Mechanical Systems

9 Webinar Series May 6, 2015 webinar Dealing with T & RH Extremes TODAY Building Envelope August 12 & Sept. 9, 2015 Understanding Mechanical Systems & Diagnosing Inefficient HVAC Operation Outdoor Climate Building Envelope Mechanical System Storage Room Storage Furniture Enclosures Collections

10 What is the Building Envelope? The physical separators between the interior and exterior environment, including the resistance to air, water, heat, light, and noise transfer.

11 Building Envelope Interactions Elements of a building envelope include the air barrier, moisture barrier, and thermal barrier.

12 The Building Envelope Moderates the effects of the exterior/unconditioned climate on the interior/ conditioned environment and the spaces that house collections Has an impact on what interior conditions can realistically be achieved

13 Interior vs. Perimeter Interior spaces are shielded from outside exposure Do experience heat gain from lights, equipment, people Perimeter spaces have walls and windows exposed to the outside Interior Interior Perimeter

14 Building Envelope Assessment Understand the building envelope and its performance limits Temperature mitigation Air movement Moisture control Vapor pressure

15 ASHRAE Building Classifications Climate Control Potential

16 Class One: Open Structures No mechanical system, little or no potential for environmental improvement

17 Class Two: Sheathed Post & Beam Structures Wood frame barns, mills, cabins Earth or wood floors, possibly shallow crawl space No vapor barriers or insulation Ventilation to reduce heat and moisture fans, windows, attic venting High air and moisture exchange rate

18 Class Three: Uninsulated Masonry or Framed & Sided Wood Structures Modest houses, offices, early industrial buildings Often wood floors over shallow crawl space or basement Single glazed windows Lack insulation or vapor barriers Mechanical systems provide temperature control only Moderate air and moisture exchange rate

19 Class Four: Tight Wooden or Heavy Masonry Structures Substantial houses, civic, educational & religious buildings Thick masonry or insulated wood frame walls attic may be insulated Single glazed or storm windows, dense foundation walls Low level heating, limited winter humidification, cool & reheat for dehumidification Low to moderate air & moisture exchange rate

20 Class Five: Newly-Built Insulated Structures Museums, libraries, offices, industrial buildings Metal or concrete-framed, insulated walls, insulated membrane or metal roofing Vapor Barriers, double-glazed windows, vestibule entries Tight construction low air & moisture exchange rate Solar gain on dark surfaces, especially roofs HVAC systems with heating & humidification, summer cooling &reheating for dehumidification

21 Class Six: Tight, Double-wall Construction Purpose-built storage vaults Metal or concrete framed, insulated walls, membrane or metal roofing Vapor barriers, no windows, vestibule entries Low air and moisture exchange rate Precision controlled heating, cooling & humidity Interior buffered from exterior by cavities and corridors at perimeter

22 Historic Building Envelope ASHRAE Classes 1, 2, 3 Originally designed to breathe Not designed for tight envelopes and environmental controls in fact trapping air or moisture inside can damage the building envelope and the structure The structure may be part of the collection limiting options for modern intervention or mechanical upgrades

23 Ventilation in Historic Buildings Windows were designed to let in light and to provide ventilation Double hung windows and above door transoms were designed for ventilation Before electricity, T- or H-shape building design with courtyards allowed air flow and daylight in every room

24 Warm/Cool Air Stack Effect

25 Impact of Stack Effect on Collection Storage Basements - Cooler due to surrounding soil temperatures, less exposure to exterior air At-grade floors - Temperature balanced between rise of cooler air and heat loads from exterior (radiant and conducted energy) and internal sources Actual temperature may be similar to outdoor temperatures Upper Floors/Attics - Hot due to rising warm air and radiant energy through the roof

26 Reduce Heat Loads/Loss in Historic Buildings Use awnings, shutters, curtains, and shades to reduce solar radiation When possible use operable windows, transoms, and attic vents for natural ventilation Where appropriate, consider replacing original windows or adding storm windows to reduce radiant energy and heat loss Minimize lighting and equipment operation Dial down radiators and close heat vents in winter (but maintain RH above 25-30%)

27 Moisture Gain & Loss The building envelope, both above and below grade, plays a role in determining the amount of moisture gain or loss that the building and its mechanical system have to deal with Sources include: Moist, humid outside air Precipitation Condensation Surface water/runoff Groundwater

28 Understanding Moisture Movement Vapor Diffusion - The movement of moisture from areas of high vapor pressure to areas of low vapor pressure In many climates, moisture moves into a building in summer, and out (if humidifying or an interior moisture source) in winter

29 Damage from Diffusion Spalling Cracks Efflorescence

30 Understanding Moisture Movement Air Leakage - Air that enters a building can carry moisture in with it Can result in higher interior moisture/rh conditions in summer, and lower in winter Can be defeated by positive pressure (with mechanical systems) or tightly sealed envelopes

31 Moisture Concerns Look for / be aware of: Liquid seepage in sub-grade/basement walls & floors Damaged gutters & downspouts - Drainage problems High levels of groundwater, underground streams, nearby ponds Vegetation close to the building Leaks at perimeter (roof, walls, windows) Gaps in perimeter or foundation vapor barriers Porous exterior walls, deteriorated masonry

32 Moisture Concerns Basement walls and floors Seepage Rising damp Drainage problems Water drained too close to building Misrouting of moisture on building site

33 Moisture Concerns Gutters, Downspouts Move water away from the building Install or maintain gutters and downspouts Monitor for and immediately repair any perimeter leaks Slope the ground away from the foundation Trim vegetation to at least two feet from the building

34 Moisture Concerns - Drainage

35 Understand Your Building Site Reroute runoff water around the building If unable, capture in drainage pipe and route under building Direct gutters into drainage line rather than into ground surrounding the foundation

36 Choose Appropriate Repairs for Historic Structures Windows Repair putty around individual lites & muntins (crosspieces) Repair sills & degraded rails Floors Gaps can be filled with hemp rope soaked in linseed oil Interior/Exterior Walls Be cautious about adding modern materials or additional layers that may change the behavior of the wall

37 Keys to Working With Historic Envelopes If required, repair to the original intent Use period appropriate methods and materials Goal is not to make the envelope tight goal is to return the envelope to its original optimal function Always consult the experts!

38 Environmental Management Many historic structures will have had some means of heating

39 Risks of Modern Mechanization Disturbance of historic structure aesthetic some sites cannot add the necessary infrastructure Historic envelopes are not designed to maintain tight control or to adapt well to modern moisture control methods

40 Condensation Humidification for collection preservation in winter can cause moisture to condense on surfaces with a lower temperature than the interior dew point Windows Walls Damage can include rotting of wooden structure or mold growth in microenvironments

41 Dehumidification Dehumidifying building interiors can create lower vapor pressures on the inside, encouraging moisture transfer through the envelope Can cause efflorescence, loosening of paint or other wall coverings

42 Vapor Barriers Installing vapor barriers on historic envelopes can lead to significant issues of structural moisture retention if not careful Their use is climate and structure specific again, consult the experts!

43 Finding the Problems Spaces don t hold uniform conditions may be different from perimeter to interior areas Stack effect, leaks in the envelope, and moisture incursion all contribute Use dew point conditions to identify moisture incursion from basements, etc.

44 Identifying Microclimates Use an infrared thermometer or dataloggers for initial diagnosis of microclimates Accuracy is important, but so are comparative values look for differences in environmental conditions, identify why they exist, and their impact Warm attic? faster rate of chemical decay Cool basement? potentially higher RH, greater risk of mechanical decay and mold

45 Attic Storage Risks Heat & dryness from solar radiation and concentration of hot air as it rises Moisture from leaks due to precipitation, overflow from gutters Pests animals, birds, insects Dust accumulation

46 Attic Storage Risks Biggest concerns are high temperatures which accelerate chemical decay Brittle, discolored paper, splitting or warping wood, cracks in veneer, accelerated aging of photos

47 Attic Storage Risks Moisture from leaks Monitor for problems Store away from potential sources of moisture Pests Monitor, block any means of entrance Heat Avoid direct sunlight Provide air circulation Dust Maintain cleanliness Cover collections

48 Attic Storage Risks

49 Basement Storage Risks Primary concern is dampness or high RH which encourages: Mold, mildew and insects which feed on leather, paper, textiles, photographs Metal corrosion Mechanical damage from swelling and warping of wood, buckling of paper, softening of adhesives, etc.

50 Basement Storage Strategies B A C D D B A C A. Avoid contact with exterior walls B. Avoid placement near warm, dry ceilings C. Avoid contact with cold, damp floors D. Avoid dust covers draped over damp floors

51 Consequences of Building Closure Many structures may only be open seasonally, or have limited seasonal hours Use data loggers to understand interior environments when building is closed High moisture contents retained in unconditioned buildings (due to high RH) in winter can lead to mold problems with warm temperatures in spring

52 Consequences of Building Closure Unconditioned building Yearly spring mold problems

53 Strategies for Improvement General Identify the priority preservation of an historic structure and creating an appropriate interior preservation environment for collections is difficult to do simultaneously Consider envelope improvements repair of original envelope in historic structures, addition of modern thermal insulation and glazing if appropriate Consider creating an appropriate collections storage microclimate in a portion of the building, or in a separate structure

54 Strategies for Improvement High RH Control moisture at the source roof drainage, surface water & subsurface water, irrigation systems management Reduce moisture vapor infiltration through the envelope entries, windows, doors, open flues, envelope perforations - but use caution when adding vapor barriers to historic buildings Introduce outside air when exterior conditions are drier than interior conditions If possible, lower RH by elevating temperature slightly (conservation heating) Use fans and air circulation to reduce the risk of mold growth and high-rh microclimates

55 Strategies for Improvement Low RH Reduce moisture vapor exfiltration through repairs to the historic envelope In winter, use lower set point temperatures (in heated buildings) to raise RH Don t heat beyond minimum necessary condition

56 Other Interventions Store collections away from high risk areas attics, basements, and exterior surfaces Employ layers of protection closed storage furniture and appropriate enclosures Enclosures Object

57 Next Webinar August 12 th 2:00 PM EST Understanding Mechanical Systems Dealing with Heat, Ventilation & Moisture Simplifying how Systems Work Modern Control Systems Understand Heat & Moisture Loads Where HVAC uses Energy Air Velocities & Tightness of Control Partnering with your Facility Manager

58 Sustainable Preservation Practices for Managing Storage Environments Project website Includes archived workshop and webinar presentations, reference material, videos, etc.

59 Please take a moment to complete the post-webinar survey that will be ed to you shortly