Building Envelopes 101

Transcription

1 Session: Foundation Building Block 1 Building Envelopes 101 Diana Hun, PhD Oak Ridge National Laboratory August 9, 2016 Rhode Island Convention Center Providence, Rhode Island

2 US Primary Energy Consumption Annual Energy Consumption 98 Quadrillion Btu Transportation 28% Residential buildings 23% Buildings consume 42% of the primary energy in the US Industrial 31% Commercial buildings 19% Source: Windows and Building Envelope R&D: Roadmap for Emerging Technologies, U.S. DOE Building Technologies Office, Feb

3 Commercial Building Primary Energy Consumption Annual Energy Consumption 19 Quadrillion Btu Heating and cooling loads Cooking 1% Other 20% Space heating 16% ~½ due to the building envelope ~½ due to internal loads, mechanical equipment and lighting Computers 4% Water heating 4% Space cooling 14% Electronics 4% Refrigeration 7% Lighting 20% Ventilation 9% Source: Windows and Building Envelope R&D: Roadmap for Emerging Technologies, U.S. DOE Building Technologies Office, Feb

4 Building Envelope Physical separator b/w interior and exterior of a building Water Air Heat/cold Components Walls Roof Windows Foundation 4

5 Energy Codes for Commercial Buildings ASHRAE 90.1: Energy Standard for Buildings Except Low Rise Residential Buildings International Energy Conservation Code (IECC) International Green Construction Code (IgCC) Exceed IECC requirements by 5% 5

6 Walls 6

7 Commercial Building Envelope Primary Energy Consumption Windows (conduction) 22% Foundation 10% Infiltration 20% Roofs 16% Walls 25% Source: Windows and Building Envelope R&D: Roadmap for Emerging Technologies, U.S. DOE Building Technologies Office, Feb

8 R value and U factor R value: measure of resistance to heat transfer (hr ft 2 F/Btu) U factor (1/R): measure of the ability of a material to transfer heat Cladding Exterior continuous insulation (CI) Exterior sheathing Cavity insulation Steel studs Drywall 8

9 Cavity Insulation Batts and rolls Fiberglass Mineral wool Loose fill and blown in Cellulose Fiberglass Mineral wool Fiberglass roll Spray foam Cellulose Spray foam 9

10 Exterior Continuous Insulation Foam boards Expanded polystyrene (EPS) Extruded polystyrene (XPS) Polyisocyanurate (PIR) Extruded polystyrene boards Rigid fiber insulation Fiberglass Mineral wool Spray foam Mineral wood boards Spray foam 10

11 DOE Climate Zones 11

12 2015 IECC Wall R Value Requirements 12

13 Roofs 13

14 Commercial Building Envelope Primary Energy Consumption Roofs 16% Windows (conduction) 22% Foundation 10% Infiltration 20% Walls 25% Source: Windows and Building Envelope R&D: Roadmap for Emerging Technologies, U.S. DOE Building Technologies Office, Feb

15 ASHRAE 90.1 DOE Climate Zone 2013 Roof R-value R-value (hr ft 2 F/Btu) Climate Zone 4 (Kansas City, MO)

16 Insulation Used in Low Sloped Roofs Expanded Polystyrene (EPS) + Low cost option Low softening temperature precludes its use under dark colored membranes Extruded Polystyrene (XPS) + Excellent moisture resistance Softens similar to EPS Polyisocyanurate (PIR) + Fire resistance and higher R/inch Fiberboard and Perlite + Structural or thermal protection layer Low R value 16

17 Cool Roof Guideline s/2013/10/f3/coolroofguide.pdf What climate zone? What happens when they get dirty? How about more insulation? How about condensation, moisture and ice? 17

18 Cool Roof Impact on an Energy Bill 18

19 Impact of Demand Charges 19

20 DOE Cool Roof Calculator Estimates energy and peak demand savings for flat roofs with non black surfaces Inputs Roof location (city and state) Roof characteristics (R value, solar reflectance, thermal emittance) Equipment data (heating and cooling energy costs and efficiencies) Demand charge details (demand charge and duration) Output Cooling and heating energy savings Demand savings 20

21 Infiltration 21

22 Commercial Building Envelope Primary Energy Consumption Windows (conduction) 22% Foundation 10% Roofs 16% Walls 25% Infiltration 20% Source: Windows and Building Envelope R&D: Roadmap for Emerging Technologies, U.S. DOE Building Technologies Office, Feb

23 Air Barrier System Prevents airflow through envelope Continuous over the entire envelope Seal gaps around penetrations Seal wall to roof joints Seal wall to foundation joints Withstands forces during and after construction Durable over expected lifetime of building Continuous air barrier Continuous air barrier Wall-to-foundation Wall-to-roof 23

24 Air Barrier Requirements Three paths to compliance Material < 0.02 L/s m 75 Pa Assembly < 0.2 L/s m 75 Pa Envelope < 2 L/s m 75 Pa Lab Tests (ASTM E2178, E2357) Field Test Blower Door Test (ASTM E779, E1827) Blower door test indicates actual air barrier performance Wall-to-foundation Wall-to-roof 24

25 Blower Door Test Buildings w/ floor area < 40,000 ft 2 Unoccupied Total execution time < ~12 hours Setup Data collection Dismantling 2012 Commercial Buildings Energy Consumption Survey ~92% of commercial buildings floor area < 40,000 ft 2 25

26 Air Barrier Impact 50 Emmerich and Persily Comply w/ code DO NOT comply w/ code Number of Buildings Buildings w/ air barriers (71% comply w/ code) Buildings w/o air barriers (23% comply w/ code) Envelope Leakage at 75 Pa (L/s m 2 ) >

27 Air Barrier Types Mechanically-fastened membrane Self-adhered membranes Fluid-applied membranes Non-insulating sheathings Insulating sheathings Spray-applied foam 27

28 Comparison of Air Barrier Types Similarities Can serve as air and water barrier and drainage plane Many manufacturers require installation training Differences Material cost Installation Procedure, training, workmanship skills, time, cost Temperature Location: interior or exterior side of wall cavity Water vapor permeance Thermal resistance 28

29 Airtightness Savings Calculator 29

30 Airtightness Savings Calculator Preliminary Results Building: DOE prototype standalone retail building Floor area = 24,700 ft 2 Wall and roof area = 37,400 ft 2 Climate: Chicago Annual Energy Cost ($K) Leakage Rate, L/s.m 75 Pa 30

31 Windows 31

32 Commercial Building Envelope Primary Energy Consumption Windows (solar heat gain) 7% Windows (conduction) 22% Roofs 16% Foundation 10% Infiltration 20% Walls 25% Source: Windows and Building Envelope R&D: Roadmap for Emerging Technologies, U.S. DOE Building Technologies Office, Feb

33 Performance Indices U Factor Measures how well a window prevents heat from escaping or entering a building Ranges from 0.25 to 1.25 Btu/h ft 2 F Lower U factor means better insulation Solar Heat Gain Coefficient (SHGC) Measures how well a window blocks heat from the sun Ranges from 0 to 1 Lower the SHGC means less transmitted solar heat Image/animation credit: Efficient Windows Collaborative 33

34 Performance Indices Visible Transmittance (VT) Measures how much light comes through a window Ranges from 0 to 1 Higher VT means more light makes it indoors Air leakage (AL) Measures how much air leaks through a window 34

35 Indices for Various Climates Lower U factor are more important in heating dominated climates (i.e., cold climates) Lower SHGC is important in cooling dominated climates (i.e., hot climates) High VT is usually preferred in all climates Lower air leakage is preferred in all climates Window Label : Image Credit : NFRC 35

36 Window Stock 5.6 million commercial buildings Source: Table Building Energy data Book, March 2012 Single pane with metal frame High U factor Highly detrimental in cold climates Clear panes High SHGC Highly detrimental in hot climates 36

37 Attachments as a Retrofit Option Attachment Indoors Outdoors U-Factor VT SHGC Air Leakage Blinds Roller shades Awnings Films Storm windows Improvement Some improvement No improvement Films Roller shades Interior storm window Exterior storm window 37

38 Surface Applied Window Film Case Study: Hyatt Regency Houston Typical installed cost Reflective: ~$4/ft 2 Neutral or spectrally selective: $7/ft 2 Low E: ~$8/ft 2 Hyatt Regency Houston Interior film Enerlogic VEP 235 (low E, e=0.05) 23,000 ft 2 of film Savings of $32,000/year Payback of 3.6 years Data: Steve DeBusk, Eastman Chemical 38

39 Surface Applied Window Film Case Study: Hyatt Regency Houston Summer performance Images and data: Steve DeBusk, Eastman Chemical Window and room configuration No film Glass warmed by sun s heat radiates heat into the room With window film Warm glass but radiating minimal heat into the room 39

40 Storm Window Case Study: GSA Office, Provo, Utah Installation and performance evaluation GSA Green Proving Ground (GPG) program GSA Office Building in Provo, Utah Installed over single pane window U factor = 0.14 Btu/hr ft 2 F (R 7.1) Total heating load reduction: 31 41% Payback of 9 years Better thermal comfort and reduced condensation Slide credit: Charlie Curcija, LBNL 40

41 Design Tool FAÇADE Design Tool: Windows for high performance commercial buildings Easy to use Select scenarios Ranks and compares the performance data Offices and schools 41

42 Building Envelope Retrofits 42

43 Insulation Requirements ASHRAE : first insulation requirements for building envelopes 2012 Commercial Buildings Energy Consumption Survey ~50% of commercial buildings built before

44 Air Sealing Requirements ASHRAE IECC 2009 First air sealing requirements for building envelopes 2012 Commercial Buildings Energy Consumption Survey ~95% of commercial buildings built before

45 Existing Windows About 50% of windows are clear single panes Source: Table Building Energy data Book, March

46 ORNL Seeks Commercial Buildings for Case Studies Gather data to estimate benefits from envelope retrofits Energy savings Payback period Retrofit in the next 3 years Building owner obtains free of charge Blower door test before and after retrofit Hygrothermal analysis of proposed retrofit Simulations that estimate potential energy savings Discounts on some air barrier and insulation materials and windows Contact Diana Hun at hunde@ornl.gov ORNL Wants To Help You Retrofit Your Building Envelope 46

47 Questions? Diana Hun 47