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Fixing uvalue for floor function
This commit is contained in:
Khalim Conn-Kowlessar
parent
202365ebf2
commit
fb0a659856
3 changed files with 70 additions and 115 deletions
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@ -61,113 +61,6 @@ class FloorRecommendations(Definitions):
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part for part in self.materials if part["type"] == "solid_floor_insulation"
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]
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def _estimate_suspended_floor_u_value(
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self, floor_area, number_of_rooms, insulation_thickness, wall_type, region, age_band
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):
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"""
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Estimate the u-value of a suspended floor, based on RdSap methodology
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Default U-value for UNINSULATED suspended floor, based on RdSAP methodology
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https://files.bregroup.com/bre-co-uk-file-library-copy/filelibrary/SAP/2012/RdSAP-9.93/RdSAP_2012_9.93.pdf
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w = wall thickness, where these estimates are based on the RD SAP methodology, as in table S3
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A = floor area
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Exposed perimeter = P
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soil type clas thermal conductivity lambda_g = 1.5 W/mK
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Rsi = 0.17m^2K/W
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Rse = 0.04m^2K/W
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Rf = 0.001 * d_ins / 0.035 where d_ins is the insulation thickness in mm
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height above external ground h = 0.3m
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average wind speed at 10m height v=5m/s
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wind sheilding factor fw = 0.05
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vantilation factor E = 0.003 m^2/m
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U-value of walls to underfloor space Uw = 1.5 W/m^2K
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# Calulations for suspended ground floors, example for 5 bedroom house with permiter estimated at
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44.36214602563767
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1) dg = w + lambda_g x (Rsi + Rse) = 0.5 + 1.5 * (0.17 + 0.04) = 0.615
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2) B = 2 * A/P = 2 * 123.0 / 44.36214602563767 = 5.545268253204708
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3) Ug = 2 * lambda_g * log(pi * B/dg + 1)/(pi * B + dg) =
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2 * 1.5 * log(3.141592653589793 * 5.545268253204708/0.615 + 1) / (3.141592653589793 * 5.545268253204708
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+ 0.615) = 0.5619604457160708
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4) Ux = (2 * h * Uw /B) + (1450 * E * v * fw/B) = (2 * 0.3 * 1.5 / 5.545268253204708) + (1450 * 0.003 * 5 *
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0.05/5.545268253204708) = 0.35841367978030436
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5) U = 1/ (2 * Rsi + Rf + 1/(Ug + Ux)) = 1 / (2 * 0.17 + 0 + 1/(0.5619604457160708 + 0.35841367978030436)) =
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0.701
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"""
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age_band_letter = [x for x in age_band_data if x[region] == age_band][0]["age_band"]
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defaults = {
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# We need width in meters
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"w": [x[age_band_letter] for x in default_wall_thickness if x["type"] == wall_type][0] / 1000,
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"lambda_g": 1.5,
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"Rsi": 0.17,
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"Rse": 0.04,
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"Rf": 0.001 * insulation_thickness / 0.035,
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"h": 0.3,
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"v": 5,
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"fw": 0.05,
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"E": 0.003,
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"Uw": 1.5,
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}
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dg = defaults["w"] + defaults["lambda_g"] * (defaults["Rsi"] + defaults["Rse"])
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# P is the exposed perimeter, which we estimate as we not have this data
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if number_of_rooms <= 2:
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p = estimate_perimeter_2_rooms(floor_area=floor_area)
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else:
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p = estimate_perimeter(floor_area=floor_area, num_rooms=number_of_rooms)
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b = 2 * floor_area / p
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u_g = 2 * defaults["lambda_g"] * math.log(math.pi * b / dg + 1) / (math.pi * b + dg)
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u_x = (2 * defaults["h"] * defaults["Uw"] / b) + (1450 * defaults["E"] * defaults["v"] * defaults["fw"] / b)
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# This is the final estimated U-value
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u = 1 / (2 * defaults["Rsi"] + defaults["Rf"] + 1 / (u_g + u_x))
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return u
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def _estimate_solid_floor_u_value(self):
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"""
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1. dt =w + g × (Rsi + Rf + Rse)
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2. B = 2 × A/P
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3. if dt < B, U = 2 × g × ln( × B/dt + 1)/( × B + dt)
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4. if dt >= B, U = g / (0.457 × B + dt)
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:return:
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"""
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# TODO: complete
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insulation_thickness = 0
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age_band_letter = "E"
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wall_type = "cavity"
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floor_area = 37.26
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perimeter = 16.2
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# age_band_letter = [x for x in age_band_data if x[region] == age_band][0]["age_band"]
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defaults = {
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# We need width in meters
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"w": [x[age_band_letter] for x in default_wall_thickness if x["type"] == wall_type][0] / 1000,
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"lambda_g": 1.5,
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"Rsi": 0.17,
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"Rse": 0.04,
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"Rf": 0.001 * insulation_thickness / 0.035,
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"h": 0.3,
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"v": 5,
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"fw": 0.05,
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"E": 0.003,
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"Uw": 1.5,
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}
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dt = defaults["w"] + defaults["lambda_g"] * (defaults["Rsi"] + defaults["Rse"] + defaults["Rf"])
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# perimeter = self._estimate_perimeter(floor_area, number_of_rooms)
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B = 2 * floor_area / perimeter
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if dt < B:
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U = 2 * defaults["lambda_g"] * math.log(math.pi * B / dt + 1) / (math.pi * B + dt)
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else:
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print("implement me")
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def recommend(self):
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u_value = self.property.floor["thermal_transmittance"]
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is_suspended = self.property.floor["is_suspended"]
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@ -433,3 +433,30 @@ s10_list = [
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table_s9 = pd.DataFrame(s9_list)
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table_s10 = pd.DataFrame(s10_list)
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########################################################################################################################
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# Table s11 is used for assigning the u-values of floors when the insulation thickness is unknown
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# which can be found on page 25 of the BRE document
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# https://bregroup.com/wp-content/uploads/2019/09/RdSAP_2012_9.94-20-09-2019.pdf
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########################################################################################################################
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s11_list = [
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{"Age_band": "A, B", "Floor_construction": "suspended timber", "England_Wales": 0, "Scotland": 0,
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"Northern_Ireland": 0, "Park_home": 0},
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{"Age_band": "C to F", "Floor_construction": "solid", "England_Wales": 0, "Scotland": 0,
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"Northern_Ireland": 0, "Park_home": 0},
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{"Age_band": "G", "Floor_construction": "solid", "England_Wales": 0, "Scotland": 0,
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"Northern_Ireland": 0, "Park_home": "25"},
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{"Age_band": "H", "Floor_construction": "solid", "England_Wales": 0, "Scotland": "25",
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"Northern_Ireland": "25", "Park_home": 0},
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{"Age_band": "I", "Floor_construction": "solid", "England_Wales": "25", "Scotland": "50",
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"Northern_Ireland": "50", "Park_home": "50"},
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{"Age_band": "J", "Floor_construction": "solid", "England_Wales": "75", "Scotland": "75",
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"Northern_Ireland": 0, "Park_home": 0},
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{"Age_band": "K", "Floor_construction": "solid", "England_Wales": "100", "Scotland": "100",
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"Northern_Ireland": "100", "Park_home": "70"},
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{"Age_band": "L", "Floor_construction": "solid", "England_Wales": "100", "Scotland": "120",
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"Northern_Ireland": "100", "Park_home": 0},
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]
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table_s11 = pd.DataFrame(s11_list)
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@ -3,7 +3,8 @@ from copy import deepcopy
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from backend.Property import Property
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from statistics import mean
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from recommendations.rdsap_tables import (
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epc_wall_description_map, wall_uvalues_df, default_wall_thickness, table_s9 as s9, table_s10 as s10
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epc_wall_description_map, wall_uvalues_df, default_wall_thickness, table_s9 as s9, table_s10 as s10,
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table_s11 as s11
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)
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@ -368,21 +369,55 @@ def estimate_perimeter_2_rooms(floor_area):
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return perimeter
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import math
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def calculate_floor_u_value(floor_type, area, perimeter, age_band, wall_type, insulation_thickness=None):
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"""
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Estimate the u-value of a suspended floor, based on RdSap methodology
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Default U-value for UNINSULATED suspended floor, based on RdSAP methodology
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https://files.bregroup.com/bre-co-uk-file-library-copy/filelibrary/SAP/2012/RdSAP-9.93/RdSAP_2012_9.93.pdf
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w = wall thickness, where these estimates are based on the RD SAP methodology, as in table S3
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A = floor area
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Exposed perimeter = P
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soil type clas thermal conductivity lambda_g = 1.5 W/mK
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Rsi = 0.17m^2K/W
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Rse = 0.04m^2K/W
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Rf = 0.001 * d_ins / 0.035 where d_ins is the insulation thickness in mm
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height above external ground h = 0.3m
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average wind speed at 10m height v=5m/s
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wind sheilding factor fw = 0.05
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vantilation factor E = 0.003 m^2/m
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U-value of walls to underfloor space Uw = 1.5 W/m^2K
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# Calulations for suspended ground floors, example for 5 bedroom house with permiter estimated at
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44.36214602563767
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1) dg = w + lambda_g x (Rsi + Rse) = 0.5 + 1.5 * (0.17 + 0.04) = 0.615
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2) B = 2 * A/P = 2 * 123.0 / 44.36214602563767 = 5.545268253204708
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3) Ug = 2 * lambda_g * log(pi * B/dg + 1)/(pi * B + dg) =
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2 * 1.5 * log(3.141592653589793 * 5.545268253204708/0.615 + 1) / (3.141592653589793 * 5.545268253204708
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+ 0.615) = 0.5619604457160708
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4) Ux = (2 * h * Uw /B) + (1450 * E * v * fw/B) = (2 * 0.3 * 1.5 / 5.545268253204708) + (1450 * 0.003 * 5 *
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0.05/5.545268253204708) = 0.35841367978030436
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5) U = 1/ (2 * Rsi + Rf + 1/(Ug + Ux)) = 1 / (2 * 0.17 + 0 + 1/(0.5619604457160708 + 0.35841367978030436)) =
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0.701
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"""
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def calculate_floor_u_value(floor_type, area, perimeter, wall_thickness, insulation_thickness=None):
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# Define constants
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lambda_g = 1.5 # thermal conductivity of soil in W/m·K
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Rsi = 0.17 # in m²K/W
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Rse = 0.04 # in m²K/W
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lambda_ins = 0.035 # thermal conductivity of floor insulation in W/m·K
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wall_thickness = [x[age_band] for x in default_wall_thickness if x["type"] == wall_type][0] / 1000
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if insulation_thickness is None:
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insulation_lookup = s11[s11["Age_band"].str.contains(age_band) & s11["Floor_construction"] == floor_type]
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if insulation_lookup.empty:
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insulation_thickness = 0
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else:
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insulation_thickness = insulation_lookup["England_Wales"].values[0]
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# Calculate Rf for insulated floors
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if insulation_thickness is not None:
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Rf = 0.001 * insulation_thickness / lambda_ins
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else:
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Rf = 0
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Rf = 0.001 * insulation_thickness / lambda_ins
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# Calculate B
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B = 2 * area / perimeter
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@ -413,7 +448,7 @@ def calculate_floor_u_value(floor_type, area, perimeter, wall_thickness, insulat
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Ux = (2 * h * Uw / B) + (1450 * epsilon * v * fw / B)
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# Calculate final U value for suspended floors
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if insulation_thickness is not None:
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if insulation_thickness > 0:
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Rf += 0.2 # adding thermal resistance of floor deck
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else:
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Rf = 0.2 # thermal resistance of uninsulated floor deck
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