Ackbs summary of 2012 iecc

Synopsis courtesy of:

Nantucket Building Science & Energy Consulting www.ackBS.com (508) 631-6633 Tom Barnes RESNET Certified HERS Rater BPI Certified Thermal Envelope Specialist LEED AP Licensed GC (MA)

Highlights: 2012 IECC - for Nantucket (Climate Zone 5A - Marine) - RESIDENTIAL CODE, Chapter 4 Note: There are two paths to meeting energy code requirements, either of which may be chosen: "Prescriptive" - simply follow what the code book "prescribes" - no "tradeoffs" are allowed this way.

"Performance" - this allows for "tradeoffs" as long as overall energy performance is achieved.

"Tradeoffs" means improving one or more elements that affect building performance allows one to select systems or assemblies that are less than the "prescriptive" requirements in the code book. For instance, choosing higher efficiency HVAC equipment, improving air sealing, and increasing ceiling insulation may allow one to use 2x4 walls with R-15 fiberglass in cavities.

Topic Area Building Label or Certificate

Building Thermal Envelope (R Values and U Factors)

Section Mandatory Requirement 401.3 Yes

Prescriptive

A permanent certificate supplied by the BUILDER or DESIGNER Applied to electric panel Showing "installed" R-values of building envelope components (roof, walls, floors, foundations, slabs, etc) Showing window U-factors and Solar Heat Gain Coefficients (NA in Zone 5) Showing results of BLOWER DOOR and DUCT TESTING Showing types and efficiencies of heating (AFUE) , cooling (SEER), and domestic hot water equipment (EF) This is the "prescriptive" approach to meeting code requirements.

PRESCRIPTIVE means follow what Table 402.1.1 says to use for Zone 5A: Windows/Fenestration: U = 0.32 or less Skylights: U = 0.55 or less Solar Heat Gain Coefficient: NA - no requirement for Zone 5A Ceilings: R-49 (see exceptions allowed) Wood-Framed Walls: R-20 or R-13 in "cavity" PLUS R-5 "continuous" on exterior Framed Floors: R-30 OR sufficient to fill floor cavity (R-19 minimum) Basement Walls (if applicable): R-15/19 (Either R-15 "continuous" on interior or exterior OR R-19 in "cavity" on interior OR R-13 in cavity plus R-5 "continuous" on interior or exterior Slabs (if applicable): R-10 plus R-5 at edge of heated slabs (thermal break) Crawl Spaces: Same as for Basement Walls (if applicable)

Synopsis courtesy of:

Nantucket Building Science & Energy Consulting www.ackBS.com (508) 631-6633 Tom Barnes RESNET Certified HERS Rater BPI Certified Thermal Envelope Specialist LEED AP Licensed GC (MA)

Highlights: 2012 IECC - for Nantucket (Climate Zone 5A - Marine) - RESIDENTIAL CODE, Chapter 4 Note: There are two paths to meeting energy code requirements, either of which may be chosen: "Prescriptive" - simply follow what the code book "prescribes" - no "tradeoffs" are allowed this way.

"Performance" - this allows for "tradeoffs" as long as overall energy performance is achieved.

"Tradeoffs" means improving one or more elements that affect building performance allows one to select systems or assemblies that are less than the "prescriptive" requirements in the code book. For instance, choosing higher efficiency HVAC equipment, improving air sealing, and increasing ceiling insulation may allow one to use 2x4 walls with R-15 fiberglass in cavities.

Topic Area

Section Mandatory Requirement Options

TWO Alternatives to the above "prescriptive approach" allowed:

402.1.3 Alternative 1

U-Factor Alternative (for individual "assemblies") If calculated U-Factor of assembly is less than Table 402.1.3 it shall be permitted.

NOTE: The U-factor for ceilings is 0.026. This "equals" an R of 38.46 - compare this with R-49 ceiling requirement above.

402.1.4 Alternative 2

Total UA Alternative (for the "total building thermal envelope") If the total building thermal envelope UA (sum of design U-factors times assembly area) is less than or equal to the UA using the values in Table 402.1.3 then the building shall be considered in compliance with Table 402.1.3.

402.2 Yes

The following are some highlighted "exceptions" and/or "requirements": 1 2 3 4 5 6

Ceilings w/ attics - R-49 requirement: if R-38 uncompressed insulation extends to outside edge of wall top plate at eaves, this is acceptable.

Ceilings w/out attics - R-49 requirement: if design does not allow for R-49, R-30 minimum can be used for up to 500 SF or 20% max.

Floors: insulation must be installed to maintain permanent contact with sub-floor decking.

Basement walls - "conditioned" basements: must be insulated.

Slab-on-Grade floors (less than 12" from grade): R-10 from top of slab vertical or horizontal. Add R-5 for heated slabs at edge.

Crawl space (UNVENTED): rather than insulate floor above, insulate crawl walls to R-15/19 from floor to finished grade plus 24" vertical or horizontal. Dirt floors in crawls must have Class 1 Vapor retarder lapped 6" and taped at seams (6 mil poly).

7 Replacement "Fenestration" - i.e. windows: must meet new code requirement of U = 0.32 or less Air Leakage - Thermal Envelope

Yes

Buildings shall be tested to show air leakage is less than 3 air changes per hour.

Test after all penetrations in building have been made.

Synopsis courtesy of:

Nantucket Building Science & Energy Consulting www.ackBS.com (508) 631-6633 Tom Barnes RESNET Certified HERS Rater BPI Certified Thermal Envelope Specialist LEED AP Licensed GC (MA)

Highlights: 2012 IECC - for Nantucket (Climate Zone 5A - Marine) - RESIDENTIAL CODE, Chapter 4 Note: There are two paths to meeting energy code requirements, either of which may be chosen: "Prescriptive" - simply follow what the code book "prescribes" - no "tradeoffs" are allowed this way.

"Performance" - this allows for "tradeoffs" as long as overall energy performance is achieved.

"Tradeoffs" means improving one or more elements that affect building performance allows one to select systems or assemblies that are less than the "prescriptive" requirements in the code book. For instance, choosing higher efficiency HVAC equipment, improving air sealing, and increasing ceiling insulation may allow one to use 2x4 walls with R-15 fiberglass in cavities.

Topic Area

Section Mandatory Requirement Code official can require an approved third party conduct testing.

A signed testing report shall be furnished to code official.

Follow requirements of Table 402.4.1.1

Fireplaces

Yes

New, wood-burning fireplaces shall have tight fitting flue dampers and outside combustion air.

Recessed Lighting

Yes

Recessed lights must be IC rated and sealed.

Yes Yes

If using a furnace, at least one programmable thermostat is required Supply ducts in attics must be minimum of R-8. All other ducts R-6 minimum.

Exception: ducts located completely inside the thermal envelope.

"Total Leakage" shall be less than 4 CFM per 100 SF of "conditioned floor area" (i.e. 4% limit).

Ducts entirely inside the thermal envelope do not have to be tested.

Building cavities shall not be used as ducts or plenums.

R-3 minimum for pipes with fluids greater than 105 F or less than 55 F. R-3 required under certain (most) circumstances.

Systems Controls Ducts Exception Duct sealing Exception Duct "plenums", cavities Pipe insulation Domestic Hot Water piping

Yes Yes Yes Yes

Equipment Sizing Heating and Cooling "Load" Calculations

403.6 Yes

ACCA Manual J (or other approved methods) shall be used to calculate building heating and cooling "loads".

ACCA Manual S (or other approved) shall be used to SIZE equipment to meet the loads.

Pools

403.9 Yes

Timers (automated on/off switches) required on all systems.

Covers are required on heated pools.

Synopsis courtesy of:

Nantucket Building Science & Energy Consulting www.ackBS.com (508) 631-6633 Tom Barnes RESNET Certified HERS Rater BPI Certified Thermal Envelope Specialist LEED AP Licensed GC (MA)

Highlights: 2012 IECC - for Nantucket (Climate Zone 5A - Marine) - RESIDENTIAL CODE, Chapter 4 Note: There are two paths to meeting energy code requirements, either of which may be chosen: "Prescriptive" - simply follow what the code book "prescribes" - no "tradeoffs" are allowed this way.

"Performance" - this allows for "tradeoffs" as long as overall energy performance is achieved.

"Tradeoffs" means improving one or more elements that affect building performance allows one to select systems or assemblies that are less than the "prescriptive" requirements in the code book. For instance, choosing higher efficiency HVAC equipment, improving air sealing, and increasing ceiling insulation may allow one to use 2x4 walls with R-15 fiberglass in cavities.

Topic Area Lighting Simulated Performance Alternative "Performance Path" (HERS Rating, RemRate Software)

Section Mandatory Requirement 404.1 Yes 405 Optional

75% of LAMPS (screw in bases) in all permanently installed fixtures shall be "high efficacy" (e.g. LED, CFL).

All "Mandatory" requirements still required including: Building Label or Certificate, Air Leakage - Thermal Envelope Testing, Programmable Thermostats, HVAC Duct Leakage Testing, Manual J/S Loads and Equipment Sizing, Pool Timers/Covers Duct insulation of R-6/8 Simulation software (e.g. RemRate) shall be used that generates a report showing that the proposed design has an annual energy cost that is less than or equal to the standard reference design.

This approach takes into account the R and U values of building thermal envelope components, air leakage and duct leakage rates, heating and cooling equipment efficiencies, and domestic hot water usage.

This "performance" or simulated method is required in "Stretch Code" towns in more than 150 towns and cities in Massachusetts.

It is also required for "utility incentive programs", LEED and other "green building" programs.