PH_Rev01.txt
Home > Flashcards > Print Preview
The flashcards below were created by user
Anonymous
on
FreezingBlue Flashcards. What would you like to do?

Outline the steps in calculating the thickness of insulation to give a required improved uvalue
 1/Exist uvalue = Re
 1/Improved uvalue = 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 uvalue of 0.15W/m2K for existing uvalue of 1.5W/m2K. Given Thermal conductivity of the insulation = 0.04W/mK
 1/Exist uvalue = Re
 = 1/1.5W/m2K = 0.67
 1/Improved uvalue = 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


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
 Heat Degree Hours Jan = Gt January
 = ( 24h x 31d x (20K  5K) ) / 1000
 = 11.16kKh

Source for average external temperatures?
MetroNorm

Qt = ?
Elemental Heat Losses





Formula for Qh =
 Qh = (Qt + Qv)  (Qs + Qi)
 or
 Heat Demand = (Element Heat Losses + Ventilation losses)  (Solar gains + Internal gains)

Calculate the Heat Demand for Jan through 100m2 of wall with a uvalue of 0.15w/m2K and a Jan Heat Demand of 11.16kKh
 Qt Jan = A x U x ft x Gt
 = 100m2 x 0.15W/m2K x 1 x 11.16 kKh
 = 167.4 kKh (for Jan)

Calculate the Annual Heat Demand through 100m2 of wall with a uvalue of 0.15w/m2K and a Gt of 60kKh
 Qt = A x U x ft x Gt
 = 100m2 x 0.15W/m2K x 1 x 60 kKh
 = 167.4 kKh