The Method For Determining The Heat Transfer Performance Of Sloping Roofs On Residential Building

This paper summarizes the recent scholars’ research results on the slope roof’thermal performance and structures; summed up the slope roofs’ heat insulationstructure and thermal insulation structure, and having the basic research on the slopingroof of Guangzhou region.Taking typical weather day of Guangzhou area as an example, study the intensityof solar radiation and heat gain is affected by slope and orientation effects in the slopefrom20degree to60degree. Use solar heat gain correction coefficient of slope roof toexpress the differences with flat roof. The orientation of the solar radiation intensityincreases with the increase of slope degrees, in the same slope, south of the solarradiation intensity is maximum, north is minimum, inclined plane solar radiationintensity is smaller horizontal plane; single or double slope roof solar radiation heat gainraised with the slope increases,, in about50degrees slope range, South heat energy ismaximum, north is minimum, after the increase of slope, east or west have moreenergy than the south, north heat is less than the horizontal plane, the other towardsslope roof is large than the flat roof; east or west’ amplification is great than south,solar heat energy of east or west is maximum, south to the second, north in theminimum level.Regarding the roof slope heat transfer process as a one-dimensional and24hourssteady periodic heat transfer process, having the same vertical projection area and thesame quantity of heat as necessary conditions for slope roof equals to flat roof. GetEPS plate and XPS plate as heat insulation layer thickness with15mm,35mm,55mmrespectively, in the slope range between20degree and45degree, calculate thecoefficient of heat transfer of single slope and double slope, fitting curve of thecoefficient of heat transfer and slope. The heat transfer coefficient of single slope roofor double slope roof increases with the slope increases, for the same grade andstructure of the roof, the heat transfer coefficient of single slope tread is that south islarger than others, east and west is basically same, north is minimum, North and Southdouble slope is the second minimum; the thickness of the thermal insulation layer have a certain influence of heat transfer coefficient and amplification, insulating layerthickness increases, heat transfer coefficient decreases, the same slope of roof heattransfer coefficient amplification decreased. According to the subtropical zone relatedstandards, gives no ceiling single slope roof and double slope roof heat transfercoefficient limit of the subtropical zone were1.17W/(m~2·K) and1.15W/(m~2·K).Through simulated the previous parameters obtained building energyconsumption and the top floor of the annual average temperature of the single slopeand double slope roof. For the same structure, single slope or double slope roof energyincreases with the slope increases, in the same slope, single slope west energy tomaximum, the East, South, north is barely difference, double slope of east-west energyis large than to the north and South; for the same structure, single slope or double sloperoof top rooms’ annual temperature decreases with the slope increases, in the sameslope, single slope West to a higher temperature slightly above the other but with littledifference, double slope East-West slightly to the north and south, but the difference issmall; with the increase of thickness of insulation layer material, single slope roofenergy consumption is reduced, the annual average temperature increase of top-floorrooms, so does double slope roof; for single or double slope construction of slope,slope caused by the different building energy range is far greater than the slope of thedifferent energy range, that means the slope changes to energy fluctuations larger;slope change produces a temperature range from greater than the slope changesproduced by temperature range, that means changing slope to the lean-to building toproom mean annual temperature fluctuations larger.On single slope roof of the equivalent heat transfer coefficient by checking, itcould not be used for the evaluation of building energy consumption, but can be usedfor the calculation of building energy consumption, double slope roof can both use. Iftakes the top room table area equal as the principle, converted into a flat roof height iscalculated, the building energy consumption is slightly less than the slope roof ofbuilding energy consumption which is not equivalent.