energy analysis for 2 single-family houses

1

URBAN DESIGN BUILD STUDIO E N E R G Y A N A L Y S I S o f 2 H O U S E SN E W C A S T L EG A R F I E L D

I N D E P E N D E N T S T U D Y | C M U | S P R I N G 2 0 1 2E L E N I K A T R I N I [ e k a t r i n i ] P R O F E S S O R : J O H N F O L A N

3

CONTENTS

A__USEFUL TERMINOLOGY AND RATINGS

B__NEW CASTLE

01. Site Analysis 02. Recommendations 03. IECC Guidelines 04. Baseline assemblies layers and specifications 05. Construction Details Recommendations 06. Energy Comparison of Baseline to First Proposals 07. Basement Alternatives 08. New scenario: Assemblies + HVAC sizing 09. Energy comparisons between different construction details 10. Final Decisions

C__GARFIELD

01. Assemblies and Construction Details 02. South Facade: R-Value and Thermal Bridges 03. REMRate Consumption Report 04. Different Scenarios Investigated

D__CONCLUSIONS

E__APPENDIX: REPORTS

4

TERMINOLOGY

“EUI, or energy use intensity, is a unit of measurement that describes a building’s energy use. EUI repre-sents the energy consumed by a building relative to its size.” (Energy Star)

EUI is a really important terminology when we are comparing several buildings and it is measured in kBTU/ft2. EUI is calculated by dividing the energy consumed in one year (kBTU) by the square footage of the building (ft2).

EUI is important because it shows how much the building consumes per square foot, hence the measure-ment is not related to the building’s size. In that way it is possible to compare the performance of several buildings with different sizes by comparing their EUIs. The U.S. average EUI is 44 kBTU/ft2 .

1 Load VS Energy Consumption:Load is the power needed from a system in order to work. Power is the rate at which energy is generated or used and it is measured in kW or BTUh. For example, the heating loads determined how much power does your heating system needs in order to run efficiently and heat the house. Another example is that a fluorescent bulb of 25 watts, needs 25 watts of power in order to function.

Energy is how much power is being used by something over a certain period of time. Energy and energy consumption is being measured in kWh or BTUs.

Consequently, when we refer to loads we mean the power that it is demanded by a system in order to work and when we refer to energy we mean how much power actually the system is consuming over a period of time.

2

Thermal Boundary is the boundary where the building’s insulation is. For an energy simulation it must be defined what is included in the thermal boundary; meaning which spaces of the building are insulated. If we could imagine the insulation layer as a line going around and wrapping our building, in order to achieve high performance, that line should be closed and continuous. That means we would not have any thermal bridges and consequently our heat losses during the winter and our heat gain during the summer would be minimized.

3

R VALUE AND U VALUE:The R-Value is the measure of thermal resistance; when a material has a big R-Value it is a better insulating material. The units it is measured in are ft2·°F·h/Btu. U-value is the overall heat transfer coefficient, and describes how a building material conducts heat. U-Value is equal to 1/R-Value, hence the greater the U-Value the more easily the heat is transfered through a material. Materials with great U-factors are not good insulating materials. The units of the U-Value are Btu/ft2·°F·h.

4

HERS score: RESNET has created HERS score as a rating system that helps in knowing just how energy efficient an already-built home is. The HERS score is a way of quantifying that information. A standard home would be 100 in the scale and an zero energy house would be between 20 and 0. A Energy Star certified building has an 85 HERS score. Whatever there is above 100 is not considered energy efficient.

5

5

USEFUL ENERGY TERMINOLOGY AND RATINGS

HERS SCORE

High Performance Buildings

Zero Energy Buildings

7

N E W C A S T L E

8

SITE ANALYSIS

WIN

TER

SUM

MER

THE PLO

T

The plot has a North-West orientation and the houses will lead that orientation in order to be aligned with the street and continue the street front. The biggest liability of the plot are the West winds dur-ing the winter, and the biggest asset the SouthWest winds during the summer. Appropriate placing of massing and windows to pro-tect from West winds and take advantage of the SouthWest ones

9

N

a

b+d

c

e

RECOMMENDATIONS

A. South openings are really important, in order to let the solar radiation penetrate the building shell, heat the house and minimize heating loads during the winter months. On the contrary during the summer, the trees on the side of Madison Avenue and the entrance porch on SouthEast will ensure the shading during the summer months and the protection from West and East summer direct sun-light. Nevertheless the louvers of the porch must be on moving modules to give the opportunity of opening up during the winter so that they do not compromise the visual comfort of the residents. [figure 1]

B. On the West facades, the window area should be the minimum possible to prevent great heat losses due to infil-tration and winter west winds.

C. For the above reasons, the entrance should be protect by the appropriate massing and orientation from the west winter winds.

D. Incorporation of secondary uses on west-facing walls [stairs, bathroom, furniture walls] to block the heat losses

E. Windows in general should be aligned in the internior part of the wall or in the middle to be protected from rain and moisture

F. Based on the climate data, due to the increase relative humidity, a dehumidification system is necessary. Hence, the incorporation of an ERV system for ventilation would bemore appropriate compared to an HRV.

moving or permanently open part to amplify visual comfort from the living room

10

IEEC 2009 GUIDELINES

WALL ASSEMBLY DETAILS

ABOVE GRADE WALLS The wall assembly’s total insulation in a wood frame wall construction should have an R-Value of 20 ft²·°F·h/Btu. This means that both cavity and continuous insulation should succeed a calculated R-Value of 20 ft²·°F·h/Btu, without taking into consideration any other material or air gaps. Specifically, the cavity insulation should have an R-Value of 13 ft²·°F·h/Btu and the continuous insulation 5 ft²·°F·h/Btu.

The corresponding U value of the assembly should be 0.057 Btu/ft²·°F·h

BELOW GRADE WALLS Unconditioned basement walls should be insulated from top of the basement down to 10 feet below grade or to the basement floor. They should have a continuous insulation of R10 ft²·°F·h/Btu and a cav-ity insulation of R13 ft²·°F·h/Btu.

FOUNDATION WALLS The perimeter insulation around the foundation walls of a slab on grade should be of at least an R-value 10 ft²·°F·h/Btu and the should go at least 2 feet deep under the ground.

INFILTRATION

ROOF WITH VENTED UNCONDITIONED ATTIC The roof assembly’s insulation R-Value should be 38 ft²·°F·h/Btu. This means that both cavity and continuous insulation should be equal or more than a calculated R-Value of 38 ft²·°F·h/Btu, without taking into consideration any other material or air gaps.

The corresponding U value of the assembly should be 0.03 Btu/ft²·°F·h

VAULTED VENTED ROOF Again the roof assembly’s insulation R-Value should be 38 ft²·°F·h/Btu.

FENESTRATION DETAILS

WINDOWS The windows maximum U-Value should be 0.35 Btu/ft²·°F·h. As far as climate sone 5 is concerned there is no definition for the SHGC.

CEILING ASSEMBLY DETAILS

Accepted infiltration should be considered when tested air leakage is less than 7 Air Changes per Hour (ACH) when tested with a blower door at a pres-sure of 33.5 psf (50 Pa)

11

BASELINE: ASSEMBLIES’ LAYERS + SPECIFICATIONS

Basement Walls LAYERS THICKNESS in R VALUE

outer layer Rigid Foam Insulation 2 10

Waterproofing Layer [Polyethylene] 0.006 0.121

CMU blocks 8 2.92

inner layer Inside Air film 0.68

Slab below grade LAYERS THICKNESS in R VALUE


Waterproofing Layer 0.0056 0.121

Cast Concrete 4 0.32


Exterior Walls LAYERS THICKNESS in R VALUE

outer layer Outside Air Film 0.17

Vinyl siding 0.006 0.61

Rigid Foam Insulation 0.75 3

OSB 0.438 0.47

Batt Insulation [14% Bridged] 5.5 21

Tyvek [high density polyethylene] 0.02 0.75

Gypsum Board 0.5 0.45

inner layer Inside Air Film 0.68Roof [attic] LAYERS THICKNESS in R VALUE THICKNESS in R VALUE

outer layer Outside Air film 0.17 0.17

Asphalt shingles 0.39 0.44 0.39 0.44

Roofing felt 0.039 0.039

OSB 0.438 0.47 0.438 0.47

Air gap >= 25mm 1

Mineral fiblr/wool [Batt high density] c.i. 3.5 11 3.5 11

Mineral fiblr/wool [Batt] bridged 14% 6.5 19 6.5 19

Tyvek [high density polyethylene] 0.02 0.75 0.02 0.75

Gypsum Board 0.50 0.45 0.50 0.45

inner layer Inside air film 0.68 0.68

Roof with attic Roof double space




CMU blocks 8 2.92











OSB 0.438 0.47




inner layer Inside Air Film 0.68




CMU blocks 8 2.92











OSB 0.438 0.47




inner layer Inside Air Film 0.68

REMRATE REPORT and CODE CERTIFICATION

Initially, after the first base-line simulation the house was not meeting code. With new proposal and recom-mendations it will be at-tempted to minimize the energy performance of the building and meet the code.

The tables on this page show the baseline data of the building’s assemblies, based on the design team’s first decisions.

12

A

B

Rigid Foam Insulation [Continuous insulation],

3/4 inch [R3]

Insulating in floor joists too, to avoid thermal bridges

Cavity Insulation 3 1/2”Continuous 12”

continuous insulation

cavity insulation

1

2

[2] Cavity Insulation 3 1/2”: Batt [R15][1] Continuous Insulation: Batt 12“ or Loose fill 12 1/2” [R38-40]>> Ventilating the unconditioned attic is important, in order not to get overheated during the summer A. Soffit Vent B. Eave dam to protect from air in case of using Loose fill insulation instead of batt

A

B


3/4 inch [R3]




cavity insulation

1

2


CONSTRUCTION DETAILS RECOMMENDATIONS

WA

LL A

SSEM

BLY

DET

AIL

VAU

LTED

RO

OF

ASS

EMB

LY D

ETA

IL

13

A

B


3/4 inch [R3]




cavity insulation

1

2


RO

OF

ASS

EMB

LY D

ETA

IL


14

SIMULATION STUDIES REALIZED IN REMRATE software VERSION V12.96

A BBASELINE with vinyl siding Features: 1. Vinyl Siding2. Asphalt Shingles3. Forced Air System

BASELINE Features:1. Metal Siding2. Metal Shingles3. Forced Air System

Comparison 1SIDING

MATERIALS

C BRADIANT SYSTEM Features:

1. Metal Siding + Shingles2. Boiler with radiant floor + 2 split systems for cooling

BASELINE Features:

1. Metal Siding + Shingles2. Gas Furnace with Air Handling Unit

Comparison 2 HVAC

SYSTEMS

The design team wanted to pursue the imple-mentation of metal on the outer layer of the building. However, that might cause implica-tions, such as the building envelope getting overheated and increasing the cooling loads during the summer. Towards this direction two simulations have been done: in case A the sid-ing was vinyl and the shingles asphalt, and in case B both the siding and the shingles were metal. By comparing the two simulation runs, the differences between the energy consump-tions are insignificant. Consequently the stu-dents could keep the metal siding for their pro-ject.

The 2nd comparison needed by the group was between different HVAC systems. The attempt was to evaluate the performance of a radiant floor (Case C), compared to a traditional air forced system (Baseline B). In case C, the HVAC included a hydronic boiler of an output capac-ity of 26 kBtus and efficiency of 84.5 AFUE. The boiler is connected to the radiant floor that distributes heat throughout the house. Cooling is being done through independent split sys-tems of SEER 18. In case B the HVAC system consists of a gas furnace with 62 kBtuh output capacity and 93 AFUE. The air conditioning unit has a performance of 18.7 SEER. As we can see from the chart the energy consumption with the radiant system is significantly lower.

66.2

64.8

66.3

66.2

ANNUAL ENERGY CONSUMPTION

ANNUAL ENERGY CONSUMPTION2%

decrease

0% decrease

15

ENERGY COMPARISON OF BASELINE TO FIRST PROPOSALS

0

10

20

30

40

50

60

70

0

10

20

30

40

50

60

70

D BINCREASED INSULATION: 1. Wall: Rigid Foam 4” - R202. Floor: Batt Insulation: 5 1/2 “ - R21

BASELINE Features:1. Wall: Rigid Foam 3/4” - R32. Floor: Batt Insulation: 3 1/2 “ - R15

Comparison 3 INCREASED INSULATION

RADIANT +MORE INSULATION: 1. Wall: Rigid Ins: 4” - R202. Floor: Batt Ins: 5 1/2 “ - R213. Radiant floor system + mini splits

E B BASELINE Features:1. Wall: Rigid Ins 3/4” - R32. Floor: Batt Ins: 3 1/2 “ - R153. Forced Air System

Comparison 4 INCREASED

INS. + HVAC

Based on the first baseline (B) created by the de-sign team, the wall detail had 2”x 6” studs, 16 o.c. , 5 1/2 “ batt cavity insulation (R21) in the between and 3/4” rigid foam continuous insulation (R3) on the outside. The U value of the wall assembly was 0.046 BTU/h °F ft2. The floor between the condi-tioned space and the unconditioned basement had 3 1/2” batt insulation of R15. In order to explore the possibilities in energy reduction based on a better building envelope, a simulation was done of case D with 4” of rigid foam continuous insulation on the outside layer of the walls (R20) and 5 1/2 batt insula-tion (R21) in the floor between basement and con-ditioned space. As we can see on the chart, there is a significant reduction in energy consumption.

66.2

58.7

66.2

60.5

In the last simulation case C and D were combined in scenario E. That means that for scenario E, the building had both increased insulation and a radi-ant floor system. This simulation was done in order to explore the possibilities of minimizing the energy consumption. Scenario E is compared to the base-line B, with less insulation and a forced air system, and as it is expected there is a decrease in energy consumption from B to E.

ANNUAL ENERGY CONSUMPTION

ANNUAL ENERGY CONSUMPTION11%

decrease

9% decrease

16

CASES A, B, C, D AND E on the HERS SCORE

In the simulation results of REMRATE, the HERS score is reported. Based on the results of all the simulations, the five different cases were identified on the HERS scale.

Cases A, B and C have almost the same ranking on the scale. Case A and baseline B have a HERS score of 60 and case C has 61.

For cases D and E, the HERS score has dropped to 58. That was expected because both cases D and E had an increased insulation, hence the losses were minimized and their en-ergy performance was optimized.

In order to achieve an even better performance, additional actions should be taken.

Possible design actions would be : 1. Eliminate the thermal bridges, 2. Maximize as possible the performance and R-Values of the assemblies 3. Re-size the HVAC systems according to the house’s heating and cooling loads.

HERS INDEX

BASEMENT ALTERNATIVES

After meeting the client, the design team was considering the option of eliminating the basement from their proposed design, for economic reasons. Three different simulations were processed in order to evaluate the changes on the en-ergy performance of the building. The first option was the building with a full basement (baseline B), the second case (F) was with a half basement and finally the third option was without basement at all (case G).

As we can see in the chart in the left, taking out the base-ment and exposing the slab on grade, increased the Energy Use Intensity of the building, which means that the energy consumption of the building increased.

However, due to the fact that the increase is not that sig-nificant, and due to the economic limitations, the group de-cided to eliminate the basement. In that case, the building’s assemblies had to change in order to make the building en-velope tighter. Moreover based on the previous simulations, the HVAC system selected was the boiler with the radiant floor and the mini split systems for cooling.

Full Basement(baseline B)

Half Basement(baseline F)

No Basement(baseline G)

100

90

80

70

60

50

40

30

20

10

0

52.156.8 59.0

ENERGY USE INTENSITY ANNUAL MBtus per sq ft

17

NEW SCENARIO: ASSEMBLIES + MECHANICAL SYSTEMS

In all the above simulations, REMRate software showed that the building was not meeting all versions of the IECC code. Moreover, due to several changes along the designing process, a new scenario had to be deter-mined. The adjustments made were related to the building’s assemblies and mechanical systems.

The new details for the building were as follows:

ASSEMBLY DETAILS R VALUE U VALUE Slab 10.00 0.100

Walls 21.74 0.046Roof (Part A) vaulted part above double-height space 55.56 0.018Roof (Part B) 52.63 0.019

Windows SHGC: 0.45 3.03 0.330

Based on the model made with the above data, the heating and cooling loads changed, hence the mechanical systems should be defined to avoid having an oversized system that would consume a lot. The heating load was 18,000 kBTUh and the cooling load was 10,500 kBTUh. As 1 ton is 12,000 BTUh, an 1.5 ton system would be required for heating and an 1 ton system for cooling.

Research among different boilers was made in order to define an 1.5 ton boiler that would have increased efficiency (AFUE). Two boilers were identified: Peerless Purefire PF50 with an AFUE of 95.09% and Buderus GB 142/24 by Bosch with an AFUE of 96%. BAsed on the right sizing and efficiency Buderus boiler was chosen.

For the cooling of the house split systems are going to be installed. The system will include two compressors (exterior units) and five evaporators. The model selected is a wall mounted system of high efficiency by DAIKIN. The model number is RKS09JEVJU it has a cooling capacity of 8,500 BTUh and efficiency of 18 SEER.

For ventilation purposes, an ERV system will be installed in the house. However, ERV systems can be oversized for a single fam-ily house. Hence, research for the smallest ERV system was made based on the list of Certified Heat and Energy Recovery Ventilators published by the Home Ventilating Institute (www.hvi.org). The ERV system selected is BR70 by RENEWAIRE LLC.

Finally, for domestic hot water (DHW) a gas tankless water heater is proposed. The model used for the simulation is SCTH-95DVN by RHEEM MFG. CO. and it is certified by Energy Star. The water heater has an energy factor of 0.94.

MECHANICAL SYSTEMS [HVAC]

A

A. Buderus GB 142/24B. DAIKIN compressorC. DAIKIN evaporator

B

C

18

ENERGY COMPARISONS BETWEEN CONSTRUCTION DETAILS

A. PERIMETER INSULATION

Rigid board Insulation R10 [2 inches]

Poured concrete Poured concrete



Poured concrete


SLAB ON GRADE

INSULATION

B. INSULATION UNDER THE SLAB C. PERIMETER+UNDER SLAB

0

10

20

30

40

50

2” r

igid

boa

rdpe

rimet

er

4” r

igid

boa

rdun

der

slab

4” u

nder

sla

b +

2” p

erim

eter

3.5

feet

Rigid board Insulation R10 [2”]Poured condrete Poured condrete

Rigid board Insulation R10 [2”]

Rigid board Insulation R20 [4”]Rigid board Insulation R20 [4”]

Poured condrete

SLAB ON GRADE

INSULATION

46.8

55.5

47.1

SLAB INSULATION In order to investigate which is the most ener-gy efficient way to insulate the slab, 3 scenarios were explored.In scenario H, the slab has a 2” rigid board insulation [R10] on the perimeter of the outer side of the foundation walls, which goes down 3.5 ft under the slab. In scenario I, the slab is insulated under-neath with a 4” rigid board insulation [R20]. In sce-nario J, the slab is both insulated underneath with a 4”rigid board insulation [R20] and on the perimeter with a 2” rigid board insulation [R10]. The rest of the assemblies: vaulted roof, roof with attic and walls were kept the same: Walls: R3 Continuous insulation [3/4” rigid board] + R21 Cavity insulation [5 1/2” batt insulation]Roof [attic+vaulted part]: R15 Cavity insulation [3 1/2” batt insulation] + R38 Continuous insulation [12” batt insulation] By looking at the results, the highest energy use intensity is encountered in scenario I with 55.5 MBtus/sq ft per year and the lowest in scenario J with 46.8 MBtus/sq ft per year. Hence we realize the importance of perimeter insulation. Even though it is possible to eliminate the under-slab insulation, it would be advisable, if the budget allows it, to put a 1” rigid board insulation [R5] under the slab as a moisture control. If water barrier is applied under the slab, the under slab insulated can be omitted. Finally, if the perimeter insulation is to be minimized, its depth under the slab into the ground shouldn’t be less than 2ft.

After the assemblies and the mechanical systems were identified in order for the building to meet code, several simulations were realized for further optimization. In those simulations the above new baseline is scenario H.

H I J

MBtus/ft

2 -yr ENERGY USE INTENSITY

ANNUAL MBtus per sq ft

19

MBtus/sqft-yr

C. PERIMETER+UNDER SLAB

WALL INSULATION

Having calculated the Energy Use intensity of the different slabs, we will use Scenario A as our baseline in order to evaluate the energy benefits of adding extra continuous insulation to our wood frame walls. In scenario A the walls includ-ed 5 1/2” of batt insulation between the joists, and continuous insulation exter-nally of 3/4” rigid board. As we can from the chart on the right, the more the continuous insulation, the less the EUI, something which was totally ex-pected. However, if we notice the changes in EUI between 3/4” - 2”, 2” - 3” and 3”- 4” they are: -2.0 MBtu/sqft-yr, -1.1 MBtu/sqft-yr and -0.7 MBtu/sqft-yr. Therefore we realize that after a point of adding insulation the differ-ences are not significant, hence the ac-tion is not cost effective. An exterior continuous insula-tion is necessary as proven earlier, and it is really important in order to avoid all the thermal bridging of the cavity in-sulation due to the joists. Hence, a 3/4” rigid board or even better a 2” rigid board insulation is preferred if it pos-sible based on the budget limitations.

WALLINSULATION

DETAILS

3/4”

RIG

ID B

OA

RD

[R3]

2” R

IGID

BO

AR

D [R

8]

3” R

IGID

BO

AR

D [R

12]

4” R

IGID

BO

AR

D [R

16]

0

10

20

30

40

50

47.1

45.1

44.0

43.3

ENERGY USE INTENSITY ANNUAL MBtus per sq ft

MOVING TOWARDS THE LAST DECISIONSBased on the simulations for the slab insulation the best op-

tions between which a decision should be made are scenario H and K. As far as the wall insulation is concerned the best and more cost-efficient options between which a decision should

be made are the 3/4” or the 2” continuous insulation. The next step will be to look in REMRate’s reports for the answer.

H

20

FINAL DECISIONS

REMRATE REPORT SCENARIO H

Based on the above REMRate report of scenario H, we can see that the building meets the code IECC 2012 and actually it surpasses the requirements by 10.4%. However, that doesn’t mean that all of the individual parts and assemblies of the house meet the code. In the breakdown of the assemblies above, we can see that the UA of the windows and of the slab are higher than the code’s requirements. However IECC works with trade-offs, hence even if not all of the requirements are met the building can still pass the code.

From the last simulations, 2 decisions should be made: A. If there is going to be under-slab insulation and B. If 2” continuous insulation on the walls is needed. Based on the report we can see that the slab does not meet the code, hence it would be advisable to add the under-slab insulation if there are no economic restrictions. In that way the performance of the building is going to improved, as we saw also on the simulations above.As far as the extra continuous insulation on the walls is concerned, as it is obvious from the report, it will not be needed, as the walls with a 3/4” continuous insulation are meeting the code.

Finally, for a better performance for the windows the following models by Pella Windows 350 Series are pro-posed.

Pella Windows: 350 Series________________________________________________________________________________________________

CASEMENT/AWNING

TYPE OF WINDOW U-FACTOR SHGC VLT%

1 11/16” Advanced Low-E IG with 3mm glass (vent) 0.28 0.24 44

2 11/16” SunDefense Low-E IG with Argon with 3mm glass (vent) 0.24 0.17 40

3 11/16” Advanced Low-E IG with 3mm glass (vent-foam insulation) 0.28 0.24 44

4 11/16” SunDefense Low-E IG with 3mm glass (vent-foam insulation) 0.27 0.18 40

5 11/16” Advanced Low-E IG with 3mm/5mm glass (vent) 0.29 0.23 43

6 11/16” SunDefence Low-E IG with 3mm/5mm glass (vent) 0.29 0.18 40

7 11/16” Advanced Low-E IG with 3mm/5mm glass (vent-foam insulation) 0.29 0.23 43

8 11/16” SunDefense Low-E IG with 3mm/5mm glass (vent-foam insulation) 0.29 0.18 40

9 1” Advanced Low-E IG with 5mm glass (vent) 0.28 0.23 43

10 1” Advanced Low-E IG with argon with 5mm glass (vent) 0.25 0.23 43

11 1” NaturalSun Low-E Triple-pane IG with 3mm glass 0.23 0.37 45

Notes: From the windows selection above, the windows with the lower U-Factor for better insulation and with higher Visual Lighting Transmission for better visual quality are the triple pane windows (number 11). However, just because they are more expensive than the double pane the second better selection would be the 1” Advanced Low-E IG with Argon with 5mm glass (number 10). Those ones have a lower SHGC too, which means that the windows are not going to get overheated during the summer. Finally, if for economic reasons windows without argon gas are preferred, I would suggest either number 9 or number 4, because they are the ones with the better U-factors. For better visual quality between the two (VLT= 43%) number 9 should be selected.

TYPE OF WINDOW U-FACTOR | SHGC | VLT%

21

From the windows selection above, the better performing windows are the triple pane ones (number 11), which have the lowest U-Factor for better insulation and the highest Visual Lighting Transmission for better visual qual-ity. However, just because they are more expensive than the double pane the second better selection would be the 1” Advanced Low-E IG with Argon with 5mm glass (number 10). Those ones have a lower SHGC too, which means that the windows are not going to get overheated during the summer. Finally, if for economic reasons win-dows without argon gas are preferred, I would suggest either number 9 or number 4, because they are the ones with the better U-factors. For better visual quality between the two (VLT= 43%) number 9 should be selected.

SCENARIO K: FINAL REMRATE REPORT - HERS SCORE

SCENARIO H vs SCENARIO KBased on the above a final simu-lation was realized (scenario K), where both perimeter and under slab insulation were implemented and the windows applied were se-lection 11 from the Pella list provid-ed above. Scenario H and K were compared in order to quantify the improvement in performance by the above design decisions.

0

5

10

15

20

25

30

35

40

45

50

MBtus/ft

2 -yr EUI (mBtus/ft2-yr)

H K HERS score for scenarios H+K

4846

23

G A R F I E L D

24

ASSEMBLIES AND CONSTRUCTION DETAILS

ASSEMBLIES LAYERS

Wall (East+West)Gypsum Board 3/4" 0.45Ba� Insula�on 5 1/2" 21Framing 2x6 - 16" OC 6"OSB Seathing 3/4" 0.47XPS Insula�on 2" 10Metal Siding 1" 0.61Wall (South + North)Plywood siding 3/4" 0.47Ba� Insula�on 5 1/2" 21Plywood siding 3/4" 0.47Basement WallXPS Insula�on 2" 10Concrete Block 6" 2.92XPS Insula�on 2" 10SlabConcrete Slab 5" 0.4Polyethylane 10 mil 0.12XPS Insula�on [edge] 4" 20RoofMetal roofing 1" 0.61OSB Seathing 3/4" 0.47Fiberglass Ba� insula�on 11 7/8" 38Wood joist 16" OC 11 7/8"Plywood Interior finish 3/4" 0.47

Assembly (from Interior to Exterior) Thickness R-Value [F hr �2/Btu]The project in Garfield is a 1920 ft2 single family house, which is two stories high. It has an almost true South-North orienta-tion, with the North facade being on the street access. It is a wood frame construc-tion with concrete blocks on the base-ment walls. The South and North facades are following a different construction from the East and West ones; they have big windows coming in prefabricated mod-ules and being placed on the facade. The layers of the assemblies as well as their R-Values are given on the table on the side.

After the simulation, REMRate verified that the house meets the IECC 2012 code and can be certified. However the EUI of the house is 40.05 kBtu/ft2 and its HERS score is 71. That means that there is space for improvement. Firstly, it is re-ally important to keep the layer of insu-lation as continuous as possible in order to minimize thermal bridges. Even though there might be an insulation break, all the pieces should be aligned. However the most important thing affecting the per-formance of the building is the North and South facade construction.

-non framing part

25

DETAIL Akeeping

the thermal boundary con-

tinuous

U Value: 0.28

Joists

U Value: 0.039

U Value: 0.044

U Value: 0.078

On the drawing above we can see the changes in the U-Value on the South Facade. The darker the orange the bigger the U-Value, and hence the bigger the heat losses. Moreover, it must be taken into consideration that wherever there is a change in color there is a thermal bridge. To minimize the thermal bridging in the framing part of the construction, and in order to prevent condensation, both 2” of rigid foam insulation should be placed on the outer side of the assembly. (Detail A)

old detail

new detail

SOUTH FACADE: R-VALUE AND THERMAL BRIDGES

26

COMPONENT CONSUMPTION SUMMARY

Date: May 19, 2012 Rating No.:

Building Name: Garfield_UDBS Rating Org.:

Owner's Name: Phone No.:

Property: Rater's Name:

Address: , Rater's No.:

Builder's Name:

Weather Site: Pittsburgh, PA Rating Type:

File Name: BASELINE_051612.blg Rating Date:

REM/Rate - Residential Energy Analysis and Rating Software v12.96 This information does not constitute any warranty of energy cost or savings.

© 1985-2011 Architectural Energy Corporation, Boulder, Colorado.

-30 -20 -10 0 10 20 30 40

Ceilings/Roofs

Rim/Band Joists

Above Grade Walls

Foundation Walls

Doors

Windows/Skylights

Frame Floors

Crawl Space/Unht Bsmt

Slab Floors

Infiltration

Mechanical Ventilation

Ducts

Active Solar

Sunspace

Internal Gains

Total

MMBtu/yr

Heating Season

4.6

14.4

2.7

2.1

14.8

2.9

2.8

1.5

-14.2

31.531.5


REMRATE CONSUMPTION REPORT

14.4 mmBtus/year

14.8 mmBtus/year

From the REMrate report below, it is obvious the effect of the facades and windows in the energy consumption, especially during the winter (heating season). What the chart shows is that for the biggest part of energy con-sumption, Above grade walls and windows/skylights are contributing the most.

However, due to design decisions, and as far as the building is meeting the code and surpassing it, the construc-tion of the South and North walls should not be changed. Further on, three simulations will be done in order to explore possible effects from: a.increase in roof insulation, b. increase in West and East walls insulation and finally c.re-sizing of the mechanical systems appropriately based on the building’s design loads.

27

0

5

10

15

20

25

30

35

40

45

50

Baseline Scenario A Scenario B Scenario C Scenario D Scenario E

COMPARISON BETWEEN DIFFERENT SCENARIOS Baseline

Baseline with 2 extra inches of con-tinuous rigid foam insulation on the exterior of the West and East walls

Baseline with 2 extra inches of continuous rigid foam insulation on

the exterior side of the roofBaseline with 4 extra inches of

continuous rigid foam insulation on the exterior side of the roof

Baseline with right-sized HVAC: a 36,000 Btu Furnace with 95

AFUE and a 1,5 ton sir conditioning unit with 18.5 SEER efficiency

Scenario with all the above design actions of Scenario A, C and D. [2” more of wall insulation, 4” more on

roof insulation + new HVAC]

Based on the above, it is obvious that the changes propose did not have a great impact on the Energy Use In-tensity of the house. Consequently, there is not a demanding action to be taken. The proper sizing of the HVAC would be helpful for the general performance of the house.

What would make a difference in the building would be to construct the North and South facades as air tight as possible. Due to the high possibility of leakage through those facades, a moderate ACH of 0.50 @ 50 Pascals was modelled for the simulation. With a proper tight construction, the infiltration rates will be lower.

40.1

MBtus/ft

2 -yr EUI (mBtus/ft2-yr)

39.2

39.5

39.1

40.0

38.2

HOME PERFORMANCE WITH ENERGY STARENERGY RATING CERTIFICATE

0

500

1000

1500

2000

2500

Hea

ting

Coo

ling

Wat

er H

eatin

g

Ligh

ts &

App

Pho

tovo

ltaic

s

Ser

vice

Cha

rge

Tota

l

$/yr

Estimated Annual Energy Cost

773.1

32.2273.6

831.6

258.6

2169.1

This Home

70

020406080

100120

Hea

ting

Coo

ling

Wat

er H

eatin

g

Ligh

ts &

App

Pho

tovo

ltaic

s

Tota

l

MMBtu/yr

Estimated Annual Energy Consumption

52.3

2.219.0 24.5

98.0

Address:,

House Type: Single-family detachedCond. Area: 1920 sq. ft.Rating No.:Issue Date: May 18, 2012

Annual Estimates*: Electric(kWh): 7486 Natural gas(MCF): 76 C02 emissions(Tons): 9Annual Savings**: $1860

* Based on standard operating conditions** Based on a HERS 130 Index Home

TITLECompanyAddress

Certified Rater:Certification No: Rating Date:

REM/Rate - Residential Energy Analysis and Rating Software v12.96 This information does not constitute any warranty of energy cost or savings. © 1985-2011 Architectural Energy Corporation, Boulder, Colorado.

The Home Energy Rating Standard Disclosure for this home is available from the rating provider.

The design team had not defined a model for Domestic Hot Water. In the simulation a 40 gallon storage water heater by A.O. SMITH Water Products, with 0.62 Energy Factor, was used. (model number: 153.331140).

The modelled HVAC for the simulation where selected by the data-base of certified products of AHRI (Air-Conditioning, Heating and Refrigeration Institute). The gas furnace is from Nordyne LCC, has a capacity of 36,000 Btu and its efficiency is 95 AFUE. (model number: FG7SD 038D-24B). The air conditioning unit is 1.5 ton, has an efficiency of 18.5 SEER and it is a Lennox model. (model number: CX34-18/24+TDR)

For further information, the AHRI database is available here: http://www.ahridirectory.org/ahridirectory/pages/home.aspx

HERS Score for Baseline HVAC: Further Information Required

DIFFERENT SCENARIOS INVESTIGATED

29

CONCLUSIONSThrough the investigation of the above two

houses, great insight was generated. Both of

them have a really good energy performance

that lies around the typical performance of

a residential building in U.S. and below that.

Taking a closer look to the simulation results

from both the houses above, we will notice

that the energy performance of the house in

Garfield could be defined as better than the

house in New Castle, as it has a lower EUI.

However, based on code and rating systems,

New Castle has a way better rating reaching

48 and 46 on the HERS Score while Garfield

is at 70. That difference is due to the differ-

ence in size between the two buildings. Gar-

field has a bigger annual energy consumption,

but as it is quite bigger than the New Castle

house its EUI comes out smaller. That is why

the New Castle house on the other hand is

rated better, because firstly it is smaller but

also is consuming less in total. Size, material

and spatial conservation are always really

important factors in the rating systems. To-

wards this end, the decision of both the de-

sign teams to minimize their space by taking

out the basements were really wise.

I hope this study will be of assistance both

the projects towards the final steps of their

realization.

31

A P P E N D I X

33

NEW CASTLE REPORTS

ACTION REPORT


Building Name: New Castle Rating Org.:

Owner's Name: Habitat for Humanity Phone No.:


Address: New Castle, PA 16102 Rater's No.:

Builder's Name:


File Name: FINAL OF THE FINALS_PERIM+UNDER SLAB INS_PELLA WINDOWS.blgRating Date:

REM/Rate - Residential Energy Analysis and Rating Software v12.96

This information does not constitute any warranty of energy cost or savings. © 1985-2011 Architectural Energy Corporation, Boulder, Colorado.

-50

0

50

100

Abo

ve G

rade

Wal

ls

Mec

hani

cal V

entil

atio

n

Sla

b F

loor

s

Win

dow

s/S

kylig

hts

Cei

lings

/Roo

fs

Doo

rs

Oth

er

$/yr

Heating Cost ($/yr)

7840 40

23 14 5

-56

-60-40-20

020406080

Inte

rnal

Gai

ns

Win

dow

s/S

kylig

hts

Cei

lings

/Roo

fs

Oth

er

$/yr

Cooling Cost ($/yr)

60

29

0

-44

Annual Energy Cost ($/yr)

Total 965

Heating 144

Cooling 45

Water Heating 66

Lights & App 452

Service Charge 259







Builder's Name:





-10 0 10 20 30

Ceilings/Roofs

Rim/Band Joists

Above Grade Walls

Foundation Walls

Doors

Windows/Skylights

Frame Floors


Slab Floors

Infiltration


Ducts

Active Solar

Sunspace

Internal Gains

Total

MMBtu/yr

Heating Season

2.4

13.9

0.9

4.0

7.1

0.1

7.1

-10.0

25.525.5


New Castle Page 2



-1 0 1 2

Ceilings/Roofs

Rim/Band Joists

Above Grade Walls

Foundation Walls

Doors

Windows/Skylights

Frame Floors


Slab Floors

Infiltration


Ducts

Active Solar

Sunspace

Internal Gains

Whole House Ventilation

Total

MMBtu/yr

Cooling Season

0.0

-0.1

-0.0

0.9

-0.3

-0.0

-0.2

1.8

-0.7

1.31.3

2012 IECC OVERALL BUILDING UA COMPLIANCE






Builder's Name:





Elements Insulation Levels

2012 IECC As Designed

Shell UA Check

Ceilings: 24.3 17.5

Above-Grade Walls: 115.5 93.3

Windows and Doors: 83.3 60.6

Slab Floor, Heated: 8.4 4.5

Overall UA (Design must be equal or lower): 231.5 176.0

Window U-Factor Check (Section 402.5)

Window U-Factor (Design must be equal or lower): 0.480 0.230

This home MEETS the overall thermal performance requirements and verifications of the International EnergyConservation Code based on a climate zone of 5A. (Section 402, International Energy Conservation Code, 2012 edition.) In fact, this home surpasses the requirements by 24.0%.

Building Elements Type U-Value Area

Ceilings

Roof R-40 BATT 0.019 549.0

Roof R-40, Vaulted* 0.018 386.0

Above-Grade Walls

Wall R-21, R-3 Cont.*META7 0.046 2026.4

Joist JOISTS BATT INS 0.065 40.5

Windows and Doors

Window PELLA WINDOWS 0.230 52.0







Door 2-1/4 Wd solid core 0.268 20.5




Slab Floor, Heated

On-Grade Perimeter SLAB ON GRADE_PERIME 0.031 145.0

HOME CERTIFIED TO MEET THE PROVISIONS OF THE2012 INTERNATIONAL ENERGY CONSERVATION CODE

This home built at

, New Castle, PAby

exceeds the minimum requirements for the 2012 International Energy Conservation Code

Building Features

Ceiling Flat: R-53 Duct: NA

Vaulted Ceiling: U-0.018 Window: U-Value = 0.230, SHGC = 0.370

Above Grade Walls: U-0.046 Heating: Fuel-fired hydronic distribution, Natural gas, 96.0 AFUE.

Foundation Walls: NA Cooling: Air conditioner, Electric, 18.0 SEER.

Exposed Floor: NA Water Heating: Instant water heater, Natural gas, 0.94 EF, 0.0 Gal.

Slab: R-10.0 Edge, R-20.0 Under

The organization below certifies that the proposed building design described herein is consistent with the building plans, specifications, and othercalculations submitted with the permit application. The proposed building has been designed to meet the 2012 IECC requirements in compliance with

Chapter 4 based on Climate Zone 5A and with all mandatory requirements.

Name: Signature:

Organization: Date: May 19, 2012

The 2012 International Energy Conservation Code is a registered trademark of the International Code Co uncil, Inc. ( “ICC”).No version of this software has been reviewed or ap proved by ICC or its affiliates.

REM/Rate - Residential Energy Analysis and Rating S oftware v12.96


0200

400600800

10001200

Hea

ting

Coo

ling

Wat

er H

eatin

g

Ligh

ts &

App

Pho

tovo

ltaic

s

Ser

vice

Cha

rge

Tot

al

$/yr


144.444.9 65.6

452.1

258.6

965.6

This Home

460

10203040506070

Hea

ting

Coo

ling

Wat

er H

eatin

g

Ligh

ts &

App

Pho

tovo

ltaic

s

Tot

al

MMBtu/yr


25.6

1.3

12.817.0

56.7

Address:

New Castle, PA 16102

House Type: Single-family detached

Cond. Area: 1425 sq. ft.

Rating No.:

Issue Date: May 19, 2012



TITLE

CompanyAddress

Certified Rater:

Certification No:

Rating Date:



35

GARFIELD REPORTS

ACTION REPORT






Builder's Name:





-300-200-100

0100200300

Win

dow

s/S

kylig

hts

Abo

ve G

rade

Wal

ls

Cei

lings

/Roo

fs

Sla

b F

loor

s

Infil

trat

ion

Fou

ndat

ion

Wal

ls

Oth

er

$/yr

Heating Cost ($/yr)

220 214

68 43 41 40

-159

-40

-20

0

20

40

60

Inte

rnal

Gai

ns

Win

dow

s/S

kylig

hts

Cei

lings

/Roo

fs

Oth

er

$/yr

Cooling Cost ($/yr)

44

111

-24

Annual Energy Cost ($/yr)

Total 1862

Heating 467

Cooling 31

Water Heating 274

Lights & App 832

Service Charge 259







Builder's Name:





-30 -20 -10 0 10 20 30 40

Ceilings/Roofs

Rim/Band Joists

Above Grade Walls

Foundation Walls

Doors

Windows/Skylights

Frame Floors


Slab Floors

Infiltration


Ducts

Active Solar

Sunspace

Internal Gains

Total

MMBtu/yr

Heating Season

4.6

14.4

2.7

2.1

14.8

2.9

2.8

1.5

-14.2

31.531.5


Garfield_UDBS Page 2



-2 -1 0 1 2 3 4

Ceilings/Roofs

Rim/Band Joists

Above Grade Walls

Foundation Walls

Doors

Windows/Skylights

Frame Floors


Slab Floors

Infiltration


Ducts

Active Solar

Sunspace

Internal Gains

Whole House Ventilation

Total

MMBtu/yr

Cooling Season

0.1

-0.1

-0.1

-0.1

0.7

-0.2

-0.1

3.1

-1.2

2.22.2

2012 IECC OVERALL BUILDING UA COMPLIANCE






Builder's Name:





Elements Insulation Levels

2012 IECC As Designed

Shell UA Check

Ceilings: 22.4 31.6

Above-Grade Walls: 138.4 93.1

Above-Grade Mass Walls: 8.2 7.6

Windows and Doors: 166.2 145.2

Slab Floor: 6.6 2.5

Basement Walls: 24.9 18.8

Overall UA (Design must be equal or lower): 366.6 298.8

Window U-Factor Check (Section 402.5)

Window U-Factor (Design must be equal or lower): 0.480 0.280

This home MEETS the overall thermal performance requirements and verifications of the International EnergyConservation Code based on a climate zone of 5A. (Section 402, International Energy Conservation Code, 2012 edition.) In fact, this home surpasses the requirements by 18.5%.


Ceilings

Roof R-30 Batt, Vaulted 0.037 861.0

Above-Grade Walls

Wall R-21, R-10 Cont.** 0.035 648.9

Wall R-21, R-10 Cont.** 0.035 761.3

Wall South Facade+Framing** 0.045 754.2

Wall North Facade+Framing 0.045 170.2

Wall CMU block 0.076 100.0

Joist S+N Facade_Level2 0.027 91.4

Joist South Facede_Level1 0.027 40.7

Joist E+W Facade_Level 2 0.021 66.1

Joist E+W Facade_Level1 0.021 52.7

Windows and Doors




Window PELLA WINDOWS2 0.280 115.4













Door 1-3/8 Wd solid, strm 0.275 23.9

Door 1-3/8 Wd solid, strm 0.275 24.2

Slab Floor

On-Grade Perimeter R-20 0.031 40.0

On-Grade Perimeter R-20 0.031 40.0

Basement Walls

Wall BASEMENT WALLS 0.037 500.5

HOME CERTIFIED TO MEET THE PROVISIONS OF THE2012 INTERNATIONAL ENERGY CONSERVATION CODE

This home built at

, , by

exceeds the minimum requirements for the 2012 International Energy Conservation Code

Building Features

Ceiling Flat: NA Duct: NA

Vaulted Ceiling: U-0.037 Window: U-Value = 0.280, SHGC = 0.230

Above Grade Walls: U-0.035, U-0.045, U-0.076 Heating: Fuel-fired air distribution, Natural gas, 96.0 AFUE.

Foundation Walls: R-21.1 Cooling: Air conditioner, Electric, 14.5 SEER.

Exposed Floor: NA Water Heating: Conventional, Natural gas, 0.62 EF, 40.0 Gal.

Slab: R-10.0 Edge, R-20.0 Under

The organization below certifies that the proposed building design described herein is consistent with the building plans, specifications, and othercalculations submitted with the permit application. The proposed building has been designed to meet the 2012 IECC requirements in compliance with

Chapter 4 based on Climate Zone 5A and with all mandatory requirements.

Name: Signature:

Organization: Date: May 19, 2012

The 2012 International Energy Conservation Code is a registered trademark of the International Code Co uncil, Inc. ( “ICC”).No version of this software has been reviewed or ap proved by ICC or its affiliates.

REM/Rate - Residential Energy Analysis and Rating S oftware v12.96


0

500

1000

1500

2000

2500

Hea

ting

Coo

ling

Wat

er H

eatin

g

Ligh

ts &

App

Pho

tovo

ltaic

s

Ser

vice

Cha

rge

Tot

al

$/yr


857.4

22.0273.6

831.6

258.6

2243.1

This Home

71

0

20

40

60

80

100

120

Hea

ting

Coo

ling

Wat

er H

eatin

g

Ligh

ts &

App

Pho

tovo

ltaic

s

Tot

al

MMBtu/yr


58.1

1.5

19.0 24.5

103.1

Address:

,

House Type: Single-family detached

Cond. Area: 1920 sq. ft.

Rating No.:

Issue Date: May 19, 2012



TITLE

CompanyAddress

Certified Rater:

Certification No:

Rating Date:



energy analysis for 2 single-family houses

Documents

r value

r f i e

t r i n i p r o f e

u value

u s p r i n g

energy comparisons

energy simulation

big rvalue