How is OTTV calculated?
The OTTV of an entire building is calculated by the weighted average of the OTTVs of the external walls and the roof of a building. Some countries in the Central America, including Jamaica and Ivory Coast, had developed their building energy standards using OTTV as a part of the requirements [4].
What is OTTV?
Overall thermal transfer value (OTTV) is one aspect of energy conservation. General approach. 1.2 An OTTV is a measure of the energy consumption of a building envelope.
What is OTTV and RTTV?
‘Applications of Overall Thermal Transfer Value (OTTV) and Residential Thermal Transfer Value (RTTV) in. buildings’ ‘Cases sharing on passive design for energy reduction and energy efficient building layout’
How do I lower OTTV?
So, the OTTV can be reduced by using lower wall U-value and lower wall absorption. Wall U-value and wall absorption can be reduced by thermal insulation the concrete brick for wall and using the light colour of wall external surface finish. Moreover introducing shades and coating on glass can reduce solar heat gain.
What is the U-value of a wall?
0.3 W/m
The best insulating materials have a U-value of close to zero – the lower the better. Building regulations currently stipulate that for a new building, the elements must have maximum U-values as follows: Wall – 0.3 W/m2k. Roof – 0.15 W/m2k.
What is overall thermal transfer value?
Overall Thermal Transfer Value (OTTV) is a measure of average heat gain into a building through the building envelope. It is a widely adopted measure in many countries for enhancing energy-efficient building design.
What are the limitations of the OTTV standard?
The biggest limitation of the OTTV method is that it only deals with the building envelope and does not consider other aspects of building design (such as lighting and air-conditioning) and the coordination of building systems to optimize the combined performance.
What is shading coefficient in glass?
Shading coefficient (SC) is a measure of thermal performance of a glass unit (panel or window) in a building. It is the ratio of solar gain (due to direct sunlight) passing through a glass unit to the solar energy which passes through 3mm Clear Float Glass.
What is a good floor U-value?
Floor: 0.13 W/(m²K). Roofs: 0.13 W/(m²K). Windows, roof windows, glazed rooflights and glazed doors: 1.4 W/(m²K).
What is U value in thermal insulation?
A U-value is a sum of the thermal resistances of the layers that make up an entire building element – for example, a roof, wall or floor. It also includes adjustments for any fixings or air gaps. The lower the U-value, the better insulated the building element.
What happens when glass and glazing with the lowest shading coefficient is selected?
Shading coefficient (SC) is a measure of thermal performance of a glass unit (panel or window) in a building. The lower the rating, the less solar heat is transmitted through the glass, and the greater its shading ability. …
When to use ottv and you value measurements?
To evaluate the thermal performance of different building designs via scientific measurements
How is ottv related to window to wall ratio?
The sensitivities of several parameters such as window to wall ratio (WWR), Shading Coefficient (SC), U-value for wall (U w) and solar absorption (α) are provided to design and optimize the thermal performance of residential buildings. It is found that U and α influence more on OTTV compared to other parameters.
How is overall thermal transfer value ( ottv ) calculated?
Based of the climatic parameters, OTTV is calculated for residential building envelope designs in Malaysia. To standardize the residential energy consumption, the researchers researched about many parameters. The American Society of Heating, Refrigerating and Air-Conditioning Engineers was introduced the Overall Thermal Transfer Value (OTTV).
What does ottv stand for in building envelope?
OTTV stands for ‘Overall Thermal Transfer Value’. It is a value that indicates the average rate of heat transfer into a building through the building envelope. Building envelope The term building envelope refers to the outermost layer of a building. It includes the roof, the walls and windows of all sides.