1. Passive Design Strategies

2. Building Energy Use LIGHTING PLUG LOADS HVAC Building envelope
THERMAL LOADS
INTERNAL
EXTERNAL
PEOPLE
HVAC system design
Equipment
Building envelope

3. Climate Gandhinagar Temperature Humidity Solar Radiation-
Direct & Diffused
Gandhinagar
In designing an energy efficient building, the climate and site are our first point of reference. They are design constraints but also a free resource of energy when needed. Climate influences many aspects of building design such as what are the key factors defining human comfort, predicting energy loads etc.
When we say climate, we are broadly looking at five parameters: Air temperature, Humidity, Amount of solar radiation, Wind characteristics (velocity, pressure, direction) and rainfall. The ECBC has classified India into five climatic zones based on these five parameters. Gandhinagar falls in the hot dry climate zone as the ECBC climate classification.
Wind
Rain

4. Gandhinagar Climate Average Annual Temperature Range: 20°C - 35°C
Average summer temperature 35°C. Maximum temperatures reach 45°C.
Minimum temperatures in winter between 10°C - 15°C
Summer daytime relative humidity between 20 to 60%
Highest humidity in July and August (Monsoon). Daytime humidity between 60 to 80%
Average annual wind speed 2 – 3 m/s
Highest wind speeds in May-Jun, reaching 10 m/s. Wind direction W and SW
Monsoon winds from SW and winter winds from NE
Avg. Annual daily global radiation: 5.8 kWh / m2 / day
Annual global radiation: 2100 kWh / m2 ; Diffused radiation: 760 kWh / m2
High number of sunshine hours: approximately 3100 hours
Avg. rainy days in a year: 35
Average annual rainfall: 750 mm

5. Passive design Strategies
That which does not use
Passive design Strategies

6. Passive Design Strategies1
BUILDING MASSING AND ORIENTATION 2
BUILDING ENVELOPE
ROOF AND WALLS
WINDOWS
AIR LEAKAGE 3
DAYLIGHTING 4
NATURAL VENTILATION

7. 1
BUILDING MASSING AND ORIENTATION

8. Building massing and orientation
Massing is the overall shape and size of the building
Orientation is the direction the building faces N S E W
North side less exposed etc.
Good building massing and orientation helps minimise external energy loads and harness solar and wind energy for human comfort

9. Ahmedabad Sun Path Summer 21st Jun Winter 21st Dec
Objective 1: to optimise the surface areas exposed to sun at different times of day for passive comfort. Or this we need to know the sun path of the location.

10. Sun exposure in different directions
Summer
21st Jun
North façade receives very little direct radiation. Only in summer mornings and evenings
Horizontal surface receives the greatest intensity
Winter
21st Dec N S E W
South façade is highly exposed in winter, but less in summer.
North side less exposed etc.
East and West façades receive high amount of radiation both in summer and winter

11. Remove / Reduce Internal Gains
Daylight
Ventilation
Sparsely populated buildings with little activity or equipment, such as many homes, generate relatively little heat from internal loads.
Densely populated buildings with high activity and/or energy-intensive equipment generate a great deal of heat, causing high internal cooling loads.

12. 1
BUILDING MASSING AND ORIENTATION 2
ROOF AND WALLS
BUILDING ENVELOPE

13. Significance of building envelope
The building envelope is the boundary between the conditioned interior of a building and the outdoors.
Humans first created shelters to provide thermal comfort and protection from natural elements, and this still remains a primary objective of buildings. The building envelope is the physical separator between the interior and exterior of a building.
This envelope should respond to the local climate
External thermal loads come from heat transfer through the building envelope from the sun, the earth, and the outside environment
The building envelope is first a protection and shelter.
It should meet this need of the occupants while reducing energy consumption.

14. Energy Loads: Building Envelope Components
Roof
Wall
Air leakage
Fenestration
Humans first created shelters to provide thermal comfort and protection from natural elements, and this still remains a primary objective of buildings. The building envelope is the physical separator between the interior and exterior of a building.
This envelope should respond to the local climate
External thermal loads come from heat transfer through the building envelope from the sun, the earth, and the outside environment
Floor

15. Heat transfer through Roof and Walls
Solar radiation
Radiation reflected
Convection
Surface heats up
Radiation absorbed
Heat conducted
Insulate to reduce heat transfer

16. Heat flows naturally from Hot to Cold.
Q = H (T1 – T2)
La chaleur (l’agitation des molécules) passe ("coule") naturellement de zones chaudes aux zones froides, en utilisant essentiellement quatre modes de transport
© Claude-A. Roulet, Apples, 2015

17. Heat Flow in Buildings When Hotter Outside When Colder Outside
© Claude-A. Roulet, Apples, 2015

18. A material that restricts the transfer of heat
Thermal insulation
A material that restricts the transfer of heat
In buildings, material that restricts the heat transfer better than structure materials
By definition, a thermal insulation material is a material that restricts the transfer of heat. This kind of definition allows any material to pretend to be a thermal insulation material. However, when building materials are considered, only materials that provide a significantly better resistance to heat flow than common materials used for the building fabric (stone, concrete, hollow and plain bricks or concrete blocks) can be considered as thermal insulation materials. So, a thermal insulating material is a material that, at relatively small thickness, presents a thermal resistance large enough for the envisaged purpose.

19. Different Insulation Materials
Mineral fibre insulation
Vermiculite
Glass foam insulation
Expanded Polystyrene (EPS)
Extruded Polystyrene (XPS)
Polyurethane Foam (PUF)
Autoclaved Aerated Concrete (AAC)

20. How does a Material Insulate ?
Reduce the density of matter to reduce conduction
Lock or suppress any fluid to avoid convection
Using opaque or even reflecting materials to reduce radiation
The physical principles used in insulating materials are the following:
To reduce conduction by reducing as much as possible the amount of matter, and use low-conductivity materials. Most of the volume of an insulating material is air or, in a few cases, other gases of even vacuum. Thermal insulation materials are therefore all lightweight.
To avoid convection by locking air (or another gases) between fibres that strongly hinder the air movement, or in foam bubbles that completely suppress air movement.
To avoid radiation by using opaque or even reflecting materials. Glassy and plastic materials used for fibres and foam walls are not transparent to thermal radiation. Thermal insulation materials could be transparent or translucent to light, but should not transmit the infrared radiation linked to surrounding temperatures.
Keep the product dry to avoid evaporation-condensation

21. Locked Air: Main thermal insulation material in Buildings
Air is a poor thermal conductor
Air is locked in foam bubbles or between fibres, preventing convection
Bubbles walls and fibres are themselves opaque to thermal radiation
These conditions are partly contradictory, and can be well realized only in vacuum, the surfaces of the warm and cold bodies being treated to make them reflective to electromagnetic radiation. In buildings, the economic aspect is essential: so it is locked air that is the main insulation material used there. The air is locked in foams or between the fibres of the insulation materials. The walls of the foam bubbles, as well as the fibres are also screens to radiation.

22. Characteristics of insulating materials
Insulating power
Density
Fire résistance
Water vapour diffusion
Resistance to water
Compression strength
Traction strength
Heat resistance
Absorption of vibrations
Absorption of aerial noise
Cost at given insulation
Grey energy
Light mineral wool +
- - ++ $
- -
Dense mineral wool -
Hemp fiber
Wood fibers $$
Wood straw -cement
Cellulose flakes
Cork
Glass foam
$$$
Cellular concrete
PUR
EPS
Graphited EPS
XPS
Silica aerogel
+++
$$$$

23. Insulation Application
External Internal Distributed

24. Thermal Conductivity κ
Property denoting a material’s inherent ability to conduct heat. It is an intrinsic material property and is temperature dependent
q = - 𝜅 Δ𝑇 𝑑 1K 1m
Amount of heat transferred in
1 second through
1 m² of an homogeneous layer
1 metre thick, under a temperature difference of
1 degree.
The thermal conductivity is the most important characteristic of an insulating material. Basically, it is the ratio of the density of heat flow rate to the thermal gradient along one direction. When the heat flows steadily in one direction only:
q = - 𝜅 Δ𝑇 𝑑
where ΔT is the temperature difference across a thickness d.
In other terms, the thermal conductivity is the amount of heat transferred per second through a block of material 1 meter tick and 1 square meter area when the temperature difference across it is 1 Kelvin (Figure 2.3). The smaller this figure is, the better is the thermal insulation provided by this material.
Smaller the thermal conductivity of a material, better is the thermal insulation provided by it.

25. Thermal Resistance: R value
Resistance of a layer of material, with thickness “d” to heat transfer
R = 𝑑 𝜅
RT = Rsi+R1+R2+R3+R4+Rse
Higher R value, better insulation
More material thickness, higher R value
Lower thermal conductivity, higher R value
0.13 m2K/W
0.04 m2K/W
What is often labelled on a product package is the R value or thermal resistance, since it is the main thermal property of a product that has a definite thickness. Also the ECBC prescribes R value or U values for walls and roofs.
This is the resistance of a layer of material to heat transfer and is proportional to its thickness, d, and inversely proportional to the thermal conductivity of the material, κ.
To calculate the R value of a component with different materials, we add the R values of the different components. Higher the R value, better the insulation

26. Heat Transfer Coefficient: U value
RT = Rsi+R1+R2+R3+R4+Rse
In building envelope components that include a layer of thermal insulating material, this layer is by far the most resisting one, and the total resistance is only slightly larger than the resistance of the thermally insulating layer. Therefore, the R-value labelled on a product package is often taken as the R-value of the complete building envelope component.
The inverse of this total resistance is the overall heat transfer coefficient U of the building element:
𝑈= 1 𝑅 𝑇
For a given temperature difference, ΔT, across a building envelope component, the density of heat flow rate, q, is proportional to its U-value:
q = U ΔT
The lower the U value, better is the insulation.
Lower U value, better insulation

27. 24-h. use buildings, hospitals, hotels, call centers, etc.
Envelope component
Climate Zone
24-h. use buildings, hospitals, hotels, call centers, etc.
Day-time use buildings
& other building types
Max U-value
Min. R-value of insulation alone
W/(m²K)
m² K/W
Roofs
Composite
0.261
3.5
0.409
2.1
Hot & Dry
Warm & Humid
Moderate
Cold
Opaque walls
0.440
2.10
0.369
2.20
0.352
2.35

28. 1
BUILDING MASSING AND ORIENTATION 2
BUILDING ENVELOPE
ROOF AND WALLS
WINDOWS

29. Heat transfer through Windows- Single Glazing
Conducted
Infiltration
Incident solar radiation
Transmitted
Absorbed
Reflected
Single glazing (Trace image)
Re-emitted
Re-emitted
Convection
Conducted

30. Heat transfer through Windows- Double Glazing
Conducted
Transmitted
Incident solar radiation
Infiltration
Reflected
Re-emitted
Heat transfer through a window involves all three modes of heat transfer; conduction, convection, and radiation.  The dominant mode of heat transfer is always changing and depends on the time, the ambient and interior temperatures, the exterior wind speed, and the amount and angle of solar radiation that strikes the window.  
Absorbed
Re-emitted
Convection
Conducted

31. Design decisions for windows
Placement and Area (Window-Wall-Ratio)
Solar Protection
Glazing and Frame Properties

32. Placement & Area (Window-Wall-Ratio)S E W
Summer
21st Jun
North façade receives very little direct radiation. More windows here.
Winter
21st Dec
South façade is highly exposed in winter, but less in summer.
Windows can be easily shaded here.
North side less exposed etc.
East and West façades receive high amount of radiation. Difficult to shade. Hence less windows here.

33. Vertical fins or small recess into the wall can shade adequately
Solar Protection
Summer
21st Jun
Winter
21st Dec N S E W
North-facing windows receive almost no direct sunlight. Only in summer mornings and evenings.
Vertical fins or small recess into the wall can shade adequately

34. Solar Protection
Summer
Winter
Horizontal overhangs can effectively cut direct solar radiation on the south façade in summer

35. South face Shading
INFOSYS, HYDERABAD

36. South face Shading
INFOSYS, HYDERABAD

37. Solar Protection N S E W
Summer
21st Jun
Winter
21st Dec
Summer
North side less exposed etc.
Winter
Low sun on east west facades
Solar azimuth angle also changes
Dynamic shading most effective on east west facades

38. External Movable shades

39. External Movable shades
COMMUNICATION BUILDING, EPFL, LAUSANNE
ROLEX LEARNING CENTRE, EPFL, LAUSANNE

40. External Movable shades: India
GOLCONDE, PONDICHERRY

41. External Movable shades: India
SABARMATI ASHRAM, AHMEDABAD

42. External Movable shades: India
SAFAL PROFITAIRE, AHMEDABAD

43. External Movable shades: India
SAFAL PROFITAIRE, AHMEDABAD

44. Window Glazing & Frame Heat transfer through Conduction U factor
Convection
Radiation
SHGC
Light
VLT

45. Solar Heat Gain Coefficient (SHGC)
SHGC is the ratio of solar (radiant) heat gain that passes through the fenestration to the total incident solar radiation that falls on it.
SHGC is a dimensionless number between 0 and 1.
FACTORS INFLUENCING SHGC:
Solar protection or shading
Type of glass & number of panes
Tints & Coatings on the glazing
Gas fill between glazing layers

46. U Factor
As with opaque envelope components, U-factors measure thermal conductivity through the window components.
FACTORS INFLUENCING U FACTOR:
The size of the air gap between glass panes
Coatings on the glazing
Gas fill between glass panes
Frame construction

47. Visible Light Transmission (VLT)
VLT is the ratio of visible light that passes through a glazing unit to the total visible light incident on it.
FACTORS INFLUENCING VLT:
Colour of glass
Tints & Coatings on the glazing
Number of glass panes

48. Different Glazing Types
Glass pane thickness (mm)
U factor W/(m²K)
SHGC
VLT
Single clear glazing 6
0.81
0.89
Double glazing (clear)
2.7
0.7
0.79
Double glazing (low-e) 3
1.8
0.71
0.75
Triple glazing (clear) 2
0.67
0.74
Double glazing, argon filled (low-e)
1.4
0.57
0.73
Source: Whole Building Design Guide
Double glazing (low-e)
SKN Envision 6
1.5
0.33
0.55
Source: Saint Gobain

49. 1
BUILDING MASSING AND ORIENTATION 2
BUILDING ENVELOPE
ROOF AND WALLS
WINDOWS
AIR LEAKAGE

50. Air Leakage
Normal air movement in and out of buildings – infiltration and exfiltration – is known as air leakage and is usually measured using air changes per hour (ACH).
As it is uncontrolled and admits or expels conditioned air, it leads to more energy consumption in conditioned buildings.
It is estimated that up to 1/3rd of a building’s HVAC energy is wasted due to air leakage.
Source: Wikipedia

51. Envelope Airtightness to reduce Air Leakage
Reducing air leakage by making the building envelope airtight is estimated to save 5% to 40% of heating and cooling energy.
An air tight envelope is needed in all buildings, in all climates, except those without any mechanical ventilation for fresh air, i.e. naturally ventilated buildings. Thus, air leakage rates are often specified with consideration of mechanical ventilation for fresh air.
Normal air movement in and out of buildings – infiltration and exfiltration – is known as air leakage and is usually measured using air changes per hour (ACH).
Source: IEA (2013), Technology Roadmap: Energy Efficient Building Envelopes, OECD/IEA, Paris.

52. Prescribed Minimum Air Leakage Rates
Air leakage rates for European Union, United States and advanced housing programmes
Normal air movement in and out of buildings – infiltration and exfiltration – is known as air leakage and is usually measured using air changes per hour (ACH).
Source: IEA (2013), Technology Roadmap: Energy Efficient Building Envelopes, OECD/IEA, Paris.

53. 1
BUILDING MASSING AND ORIENTATION 2
BUILDING ENVELOPE
ROOF AND WALLS
WINDOWS
AIR LEAKAGE 3
DAYLIGHTING

54. Design decisions for Daylight
Space geometry
Light reflecting features
Light shelves etc.
Internal surfaces

55. Higher the window, deeper the daylight penetration in the room
Space Geometry
Daylight penetrates into a room roughly 2.5 times the height of the top of the window from the ground. H
2.5 H
2.5 H
Higher the window, deeper the daylight penetration in the room
Usually, daylight penetration in the room is between 6m to 8m from the fenestration

56. Space Geometry
Shallow floor-plates provide daylight access to greater floor area
Building spaces can be zoned to place areas requiring more daylight near the perimeter.
Areas requiring less daylight placed in the centre of the floor-plate

57. Light Reflecting Features
Light shelves help better day light distribution while also providing shading
Lighter colours on interior surfaces reflect light better.
Helps in daylight distribution and reducing glare.

58. Daylighting Example
INFOSYS, HYDERABAD

59. 1
BUILDING MASSING AND ORIENTATION 2
BUILDING ENVELOPE
ROOF AND WALLS
WINDOWS
AIR LEAKAGE 3
DAYLIGHTING 4
NATURAL VENTILATION

60. What is Natural Ventilation?
Natural ventilation is the process of supplying and removing air through an indoor space without using mechanical systems.
When wind hits the windward facade, it creates a positive pressure on the facade. Similarly, as it flows away from the leeward facade, a region of lower pressure will be created. This pressure difference will force air movement.
Stack or buoyancy-driven ventilation relies on the temperature difference between the air inside the building and the outdoors to drive the flow. Warmer air is lighter than colder air, which is heavier. When there is a building full of warm air and it is exposed to an environment with cooler air, and two vertically spaced windows  are opened, the lighter air will escape through the to opening and the colder air will enter the building through the lower window.
Wind driven natural ventilation
Buoyancy driven natural ventilation

61. Purpose of Natural Ventilation
To provide an acceptable indoor air quality (IAQ)
To provide thermal comfort by providing a heat transport mechanism
Cooling of indoor air by replacing or diluting it with outdoor air as long as outdoor temperatures are lower than the indoor temperatures.
Cooling of the building structure i.e. Thermal mass of building.
A direct cooling effect over the human body through convection and evaporation.

62. Potential for Natural Ventilation in Gandhinagar
25% of the hours of the year the outside air temperature in Gandhinagar is below 24°C

63. Communications Building, Federal Institute Of Technology, Lausanne

64. Communications Building, Federal Institute Of Technology, Lausanne

65. Swiss Federal Office For Statistics, Neuchâtel

66. Swiss Federal Office For Statistics, Neuchâtel

67. Swiss Federal Office For Statistics, Neuchâtel

68. Recap of Passive Design Measures

69. Recap of Passive Design Measures1
BUILDING MASSING AND ORIENTATION
Buildings with longer facades towards north and south
Shape the building to mutually shade

70. Recap of Passive Design Measures2
BUILDING ENVELOPE
Insulation on the roof and walls to reduce heat transfer
Seal air –conditioned buildings to prevent air leakages
Shade windows to cut-off direct solar radiation from falling on the windows
High performance window frame and glazing

71. Recap of Passive Design Measures3
DAYLIGHT
Place large windows on north and south facades
Zone building spaces to place areas needing daylight at the perimeter
Place windows higher up on the wall, near the ceiling for better daylight distribution
Light shelves to reflect light deeper into the room
Light coloured internal surfaces for better light reflection

72. Recap of Passive Design Measures4
NATURAL VENTILATION
In Gandhinagar, natural ventilation is feasible in late nights during summer and the winter months.
Natural Ventilation useful only when outside temperature is lower than inside temperature
Different operation schedule for windows and other openings at different times of the year
Shallow floorplate assists better ventilation
Atriums and openings at different levels assist stack ventilation
Provide operable windows (with proper sealing) to have the option of natural ventilation

73. Thank you