ETC Non-Fossil Sources of Energy

Clerestory Window

  • Window dimension estimation 6 ft by 18 ft
  • January daily vertical south facing insolation
    • 950 BTU/ft^2/day

Looks like a result of 100 kBTU per day.

In [11]:
insolation = 950 * u.BTU / (u.feet**2 * u.day)
length = 18 * u.feet
width = 6 * u.feet
950 * 6 * 18
(insolation * length * width).to(u.megajoule/u.day)
Out[11]:
108.248730478812 megajoule/day

Occupant Radiant Energy

  • 50 students present for 2 hours
  • Students radiate 100W each

Result is about 10 kWh per day.

In [2]:
50 * 2 * 100
Out[2]:
10000

Measured Gas Use

Date Reading (100 cu ft)
15 Dec 2015 3254
25 Jan 2016 3372
02 Feb 2016 3375
  • conversion rate 1000 BTU = 1 cubic foot natural gas
  • 46 days between 02 feb and 15 dec observations

To get an estimate of the NG use over January, we calculate the average daily energy between 2 Feb and 15 Dec.

Result about 263 kBTU per day

Incomplete formula: $$ (E_f - E_i)f_m $$

In [5]:
num_days = 46
BTU_per_CF = 1000
meter_factor = 100
final_reading = 3375
initial_reading = 3254
(final_reading - initial_reading) * meter_factor / num_days * BTU_per_CF
Out[5]:
263043.47826086957
In [7]:
from pint import UnitRegistry
u = UnitRegistry()
In [0]:
time = 46 * u.days
In [25]:
from pint import UnitRegistry
u = UnitRegistry()
u.define('USD = []')
ng_cost = 100 * u.USD / u.therm
In [36]:
power_per_occupant = 100 * u.watt
occupants = 50
total_power = occupants * power_per_occupant 
print('total power =', total_power)
occupant_energy = total_power * 2 * u.hour / (1 * u.day)
print('occupant energy', (occupant_energy).to(u.megajoule/u.day))
print('occupant energy', (occupant_energy).to(u.kBTU/u.day))
print('avoided cost', (occupant_energy * ng_cost).to(u.USD/u.day))

total power = 5000 watt
occupant energy 36.0 megajoule / day
occupant energy 34.12141633127943 kilobtu / day
avoided cost 34.12141633127941 USD / day
In [24]:
insolation = 850 * u.BTU / u.feet**2 / u.day
insolation.to(u.watt/u.meter**2)
total_insolation = insolation * 6 * u.feet * 18 * u.feet
print((total_insolation).to(u.megajoule/u.day))
print((total_insolation).to(u.kbtu/u.day))

96.854127270516 megajoule / day
91.8 kilobtu / day
In [38]:
#15 Dec 2015 | 3254 |
#| 25 Jan 2016 | 3372 |
# 02 Feb 2016 | 3375

u.define('cfng = 1000 * btu')

energy_use = ((3375 - 3254) * 100 * u.cfng)/(45 * u.day)
print('measured natural gas use', energy_use)
(energy_use).to(u.megajoule/u.day)
(energy_use * ng_cost).to(u.USD/u.day)

WARNING:pint.util:Redefining 'cfng' (<class 'pint.unit.UnitDefinition'>)

measured natural gas use 268.8888888888889 cfng / day
Out[38]:
268.88888888888897 USD/day