skyshelves
Daylights Skyshelves

An introduction to Skyshelves

Glass windows or walls are used in buildings in order to increase the beauty of the building and to bring sunlight into the building. Ironically, binds are used to cover the glass and obstruct the sunlight.

Problems with normal glass

The below images depict the common problems with normal glass.

Building up of hot spot
Building up of bright spot and less penetration of sunlight
Blinds obstructing sunlight
Excessive glazing causes radiant heat gain
Reflective and tinted glass reduce visible transmission and compromise on day lighting
Extensive external shades has to be built to achieve optimum thermal control
Spectrally selective coated glass increase transmission as well as radiant heat
Blinds do not reject radiant heat. They obstruct view as well.
The daylight is high only near the windows

Some common problems that can be inferred from the above images are

  • Heat buildup due to the formation of hot spots
  • Blinds has to be used additionally to prevent the sunlight coming inside.
  • In spite of having a  glass window that allows natural sunlight inside, it is blocked and the electrical lights are used in the daytime.
  • Radiant Heat gain
  • Non uniform lighting

Skyshelves

The use of skyshelves daylights helps to overcome this shortfall. It eliminates the glare, but at the same time, penetrates the sunlight deep into the building. This eliminates the heat and glare while providing natural sunlight into the building. This reduces the use of electrical lights inside the building. Since the use of electrical lights is eliminated, the heat build up inside the building is also avoided. This reduces the air conditioner’s load to a great extent. Overall, the use of skyshelves reduce the power consumption.

Types of Skyshelves

Skyshelves are of two types

  • Day Glazing
  • Vision Glazing

Skyshelves Day Glazing

Day glazing is a panel of glass placed below the roof on the walls to redirect the sunlight onto the roof of the buildings. Since most of the roofs are white in color, the sunlight is reflected on the floor, thereby increasing the lighting of the floor area. The day glazing brings sunlight in to the building and avoids the heat buildup. The below images depict the working of day glazing.

Day Glazing reflecting the sunlight on to the roof
The day glazing panel can be tilted in an angle to optimise sunlight coming inside
The day glazing throws the sunlight to a larger areas
Sunlight being reflected by day glazing
Sunlight penetrated deep into the building
Day Glazing panels have more lux levels when compared to normal glass
Increased inclination of Day Glazing increases the lux level
GlazingU ValueSHGC
Single Glazed5.0 w/sq.m.  k0.7
Double Glazed2.8 w/sq.m. k0.6

Glass Specification: 5 mm clear with 12mm air gap; 

U Value – U Value is the rate of heat transfer through a structure divided by the difference in temperature across structure.

SHGC – Solar Heat Gain Coefficient is the fraction of incident solar radiation admitted through a window, both directly transmitted and absorbed and subsequently released inward. It is expressed between 0 and 1.

Application images

Cost Benefit Calculations

Assumptions

Room Floor Area100 Sq.m.
Required Illumination300 lux
Roof Reflectivity80%
Skyshelves Light Transmission65%
Lumen required by 100 Sq.m. room floor area1,20,000 lumen

Facts

Day Glazing Skyshelves required to produce 1,20,000 lumens2.5 Sq.m.
Electrical light required to light up 100 Sq.m. area (at 80 lm per watt)1.5 KW
Energy Saving at 9 hours usage a day at an unit electricity cost of Rs. 8 for 300 days1.5 x 9 x 8 x  300 = Rs. 32,400 per annum
Cost of 2.5Sq.m Day Glazing SkyshelvesRs. 20,000
Return on Investment7.5 months
Other Benefits Savings in Air Condition cost (no heat build up due to switching off of electrical lights)

Advantages of Day Glazing

  • Building spaces get bright daylight
  • Uniform illumination 
  • Savings in electricity cost
  • Delivers light even in diffused lighting conditions

Skyshelves Vision Glazing

Skyshelves vision glazing increases the daylighting inside the building and reduces the need for electrical lights. It provides an excellent choice for architects and builders to balance light and heat of sunlight.

Normal glass has hot spot on the floor
Vision Glazing allows sunlight without glare
Skyshelves Vision Glazing rejects raidant sunlight, glare and heat
Skyshelves working principle
Skyshelves working principle
Hot Spot replaced by shading effect due to skyshelves vision glazing 
Light Transmission Vs Sun elevation angle
Sun elevation angleSHGCU ValueVision Transmission
00.62.5w / sq.m. K65%
40° – 60°0.2          –

Glass Specification: 5 mm clear with 12mm air gap;  

U Value – U Value is the rate of heat transfer through a structure divided by the difference in temperature across structure.

SHGC – Solar Heat Gain Coefficient is the fraction of incident solar radiation admitted through a window, both directly transmitted and absorbed and subsequently released inward. It is expressed between 0 and 1.

Skyshelves Vision Glazing Application Images

Features and Benefits of Vision Glazing

  • No use of blinds, both internal and external leading to cost saving
  • It cuts off glare and heat gains resulting energy saving
  • Provides diffused daylights, thus helping to reduce enegry
  • Reduces air conditioner’s operational cost
  • Provides good vision tranmission

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