Outline the steps in calculating the thickness of insulation to give a required improved u-value
1/Exist u-value = Re
1/Improved u-value = Ri
Required additional resistance Rr = Ri - Re
Thickness Extra insulation = Rr x Thermal Conductivity of insulation
Calculate the thickness of extra insulation to give a required improved u-value of 0.15W/m2K for existing u-value of 1.5W/m2K. Given Thermal conductivity of the insulation = 0.04W/mK
1/Exist u-value = Re
= 1/1.5W/m2K = 0.67
1/Improved u-value = Ri
= 0.15W/m2K = 6.67
Required additional resistance Rr = Ri - Re
= 6.67 - 0.67 = 6.0
Thickness Extra insulation = Rr x Thermal Conductivity of insulation
= 6 x 0.04 = 0.24m
Gt = ?
Heat Degree Hours
What is Gt for Dublin?
60 kKh/a = 60 kilo Kelvin hours per annum
What is the Energy Balance Formula?
Heat Losses = Heat Gains
What Heat Losses are considered for the Energy Balance?
Losses: Windows + Walls + Floor + Roof + Air Leakage
What Heat Gains are considered for the Energy Balance?
Gains: Solar + Internal + Heating (Heat Demand)
Annual Heat Demand for Building = ?
= GFA x ??kWh/m2/y
Annual Heat Demand for 200m2 Building with Heat Demand of 15kWh/m2/yr= ?
= GFA 200m2 x 15kWh/m2/y = 300kWh/yr
Calculate Annual Heating Costs if Annual Heat Demand = 3000kWh/yr at cost of 0.10/kWh
Cost = 3000 x 0.10 = 300
Dublin GrassTetany = ?
60kKh/a (kilo Kelvin hours per annum)
Calculate Gt for Jan given the average external temp = 5 deg K