In India 35% of total energy being consumed for buildings and it is growing 8% annually. The growing energy demand for buildings leads from traditional biomass to commercial fuels, this results in increasing carbon emissions and aggravates power shortages in India. Fenestration system are the largest elements for energy loss in buildings. Accurate and exact evaluation of transfer performance is critical in determining overall use of energy in building. Hence, two dimensional (2-D) heat transfer analysis transfer can be used to determine thermal performance as three dimensional (3-D) may be complex one as compared to 2-D. All two dimensional results can be analyzed using WINDOW and THERM software while, practical experiment can be analyzed using hot box method but it is too expensive for each product. Results were obtained for broad range of products in market with frame materials, spacers, insulated glass units (IGU). All 2-D results were obtained with THERM6/WINDOW6. All three modes of heat transfer mechanism were incorporated in heat transfer modeling. For energy transfer we have to determine U factor i.e. heat transfer coefficient which tells about heat transfer Results shows that different material had great impact on the performance of heat transfer while, the spacer systems did not have much impact on the 2-D results as it only focus on reducing moisture content of building fenestration and prevent from mold development. It can be concluded that if we concentrate on different material and varies boundary conditions we get different results which can be great help in reducing global warming and heat transfer that is contrast reducing energy loss

1. HEAT TRANSFER THROUGH
FENESTRATION SYSTEM
M.TECH THESIS
Presented by:
SRIJNA SINGH
(10/IME/052)
Under Guidance of:
Dr. H.C Thakur
(Dept. of Mechanical Engineering,
Gautam Buddha University) July/ 2015

2. What is
Fenestration?
❑ The opening in the walls of building
structure(window, doors, louvers, vents, curtain
walls)
❑ Main components of Fenestration are:
✓ Framing: the material that keeps glazing intact.
✓ Glazing system (glass): the material that let the
visible light to pass.
✓ Spacer system (sealing of edges) Fig: Heat transfer mechanism through
Fenestration*
* Peter Harris/Building Green 2/19

3. 3/19
Need to study heat transfer through fenestration
❑ Windows and fenestration into building design is
an integrated design activity.
❑ To come out with the solution for reducing
green house effect.
❑ Conservation of energy .
❑ Alternatives of existing fenestration material.
* IEA (2022), Buildings, IEA, Paris. (Data has been updated)
* Global ABC Global Status Report 2018, EIA
Fig: Annual Global CO2 Emissions*

4. 4/19
Materials used for fenestration system
❑ Windows, doors, skylights etc. are made of different materials like wood, aluminium,
steel, fiberglass, vinyl frame with and without spacer.
Fig: Aluminium window
Fig: Fiberglass skylight
Fig: Wooden window

5. Objectives:
❑ To study and analyse the heat transfer through fenestrations (windows, doors, roofs,
louvers etc).
❑ To calculate and compare
✓Resistance(R)
✓Heat loss factor(U)
✓SHGC (solar heat gain coefficient)
✓VT (visible transmittance)
✓Overall heat transfer(Q).
❑ To calculate conduction ,convection and radiation among all.
❑ Optimization of fenestration system.
5/19

6. Methodology
✓ Measurement
of fenestrations
(windows,
doors etc.)
✓ Values from
software
✓ Software used
- WINDOW 6
✓ Solid modelling
✓ R, U and Q
✓ Software used-
Auto Cad
Inventor,
WINDOW6,and
THERM 6
✓ R, U and Q
(Using equations)
✓ Comparison of
both the values
obtained.
✓ Compliance with
other experiments
and technical
papers
✓ Development of
new optimized
fenestration
system design.
✓ (Based on the
previous
experimental
study)
6/19
Step 1 Step 2 Step 3 Step 4 Step 5
Data collection Analytical Calculations
Numerical
Calculations
Comparison
& Validation
Optimization

7. 7/19
Table: Properties of material
CASE 1: Comparison of heat transfer through two different materials window

8. 8/19
Fig: Infrared distribution of wood and AI
Fig: Isotherm distribution of wood and AI
Results and discussion (Case 1)
❑ The max temperature for wood is 21°C and minimum is -18°C, while minimum temperature for
aluminium is -17°C.

9. 9/19
Width
(mm)
Height
(mm)
Framing
material
Glazing
system
Spacer
type
CASE 2 Poly Vinyl
fixed
without
spacer
1200 1500 PVC Double
glazing
----------
CASE 3 Vinyl fixed
with spacer
1200 1500 PVC Double
glazing
Intercept
with PIB
seal
Properties and sizing of the window used

10. CAD sketch of window frame
10/19
The 2D CAD model of the vinyl frame is made in AUTOCAD
Spacer
*Units in inches
❑ Spacer is being used between double
glazing glass with primary & secondary
seals
❑ Primary seal is of PIB (polyisobutylene)
❑ Secondary as IGU Spacer with foam

11. Boundary conditions for NFRC simulation
Variables SI Unit IP Units
Outside temp - 18°C 0o F
Inside temp 21°C 0o F
Wind speed 5.5m/s 12.3 mph
Wind direction Windward Windward
Sky emissivity 1.00 1.00
11/19
Table: Boundary conditions

12. Results and Discussion (Case 2)
Isotherm Distribution:
❑ These are equal temperature lines at U factor.
12/19

13. Results and Discussion (Case 2)
❑ The color legend is representing the varying
temperature for Vinyl/Wood Frame with double
glazing glass.
❑ The gaps between double glazing is filled with
air.
❑ The thickness of air filled in the gaps is 0.650
inches.
13/19

14. 14/19
Results and Discussion (Case 3)

15. ❑ The sealant used in edge seal structurally bonds
the glass panes and spacer bars providing a high
level of moisture vapour and gas diffusion
resistance.
15/19
Results and Discussion (Case 3)

16. CASES FRAME (U factor) EDGE (U factor)
CASE 1 (Vinyl Frame window without spacer) 0.5160 0.3039
CASE 2 (Vinyl Frame window with spacer) 0.3447 0.2340
Comparison between CASE 2 and CASE 3
❑ Here it can be depicted that the value of U factor for frame and edges are decreasing
for CASE 2 i.e., Vinyl Frame window with spacer.
❑ This means that the heat loss in CASE 2 for decreasing U value will be less.
16/19
Results and Discussion

17. Chart comparing the results
0
0.1
0.2
0.3
0.4
0.5
0.6
Case 1 Case 2
U-factors
Frame Edge
17/19
2 3

18. ❑ Wood is found to better element for less heat transfer as it is having lesser U
factor value.
❑ Wood can be as a safer material for using in fenestration system specially for
the cold regions as it prevent heat transfer.
❑ Spacers conductivity do not play significant role in difference for U factor value
as it has almost same value as window without spacer, but it prevents moisture
and mold formation and compact window increasing its life.
18/19
Conclusion

19. 19/19
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temperature of windows
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temperature control in buildings via an optimal tuned PI strategy; International journal of engg &
innovative technology
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systems
4. Carlos E.Ochoa, Myriam B.C Aries, Evert J.van Loenen & Jan L.M Hensen (2012); Consideration on
design optimization criteria for windows providing low energy consumption& high visula comfort.
5. Patrick Roppel, Peng & Mark Lawton (2012); Evaluating condensation resistance for the design of wall
assemblies.
6. A.karami, Yousefi, D.Ghashghali & E. Rezaei (2011); The application of imperalist competitive
algorithm in optimizing the free convection heat transfer; International journal of modelling &
optimization.
7. Shreya Dave, Marilyne Andersen (2011); Practical & Policy - Relevant Performance metrics for
complex fenestration system.
References