Specification of a cost model for house equipment change scenarios based on global energy consumption estimates (kWh / year)

[SebastienBocquet]

We want to estimate the cost balance over the next N years of new energy equipment choices (scenarios below).

Consider the baseline house has standard equipment: electricity or gas hot water tank, electricity or gas heating,
and possibly a wood-burning stove.

Inputs are:

• Split of the annual energy consumption per component:

  • heating,
  • hot water,
  • electricity misc (lighting, washing machine etc..),
  • stove,
  • air-conditioning,
  • ventilation

• Current price and evolution of price over the next years (hmm maybe hard to guess) of:

  • electricity,
  • injected electricity (PV),
  • gas,
  • wood

To estimate the split of energy, for an electric hot water tank generally, it runs during off-peak hours.
If the electricity consumption per hour is available, it should be possible to have a good estimate of the hot water energy consumption.
One difficulty may be if electricity is used for heating: it may be difficult to isolate the heating energy consumption.
Same difficulty if gas is used both for heating and hot water.
Same difficulty for air-conditioning.
For ventilation, we can estimate an energy loss from the mass flow rate, the house temperature and the exterior température.

scenario 1: move to solar panels

Assumption: self consumption ratio, with one month or season resolution.
The production during winter is lower than in summer, so a production profile must be estimated with month or season resolution
(the delta between winter and summer may be obtained from libraries like pysolar, which provides the solar radiation
for a given location and time).
Possible improvement is to take into account the decrease of solar panel efficiency.

Then we can compute the cost balance of the solar panel over n years:
cost : solar panel initial cost.
benefit:

• n kWh self consumed per month or season, obtained from Solar panel max power times the self consumed ratio.
• reinjected kWh per month or season.
  Then integration over one year gives the electricity saving in kWh, and the reinjected kWh.

Note: if we want to estimate the self-consumption ratio, it requires an estimate of electric energy demand per season with hour resolution
and a model for production per season with the same resolution.

scenario 2:
improve wall/roof insulation:
for gas heating, the energy for heating is known.
If gas also serves for hot water, an assumption must be made to discriminate between heating and hot water.

Cost: material and installation initial cost
benefit:
a thermal resistance model can estimate the energy savings (kWh / year),
by computing the delta beween a simulation (Francois' model) with and without the new insulation.

scenario 3:
move to thermal roof panel hot water tank.
We assume the energy demand for hot water is known (kWh / year).

Cost: material and installation initial cost
Benefit:
For a heat pump based system, the COP gives the energy savings.
For a thermal panel system, I don't know if there are estimates of thermal / electric resistance energy ratio.
Certainly depends on the location of the house.

scenario 4:
move to heat pump for heating.

Cost:
material and installation initial cost + periodic controls (but there are also periodic controls for a gas system).
Note: the switch to heat pump may be done only for some rooms, and thus lead to an increase in wood consumption
in case of a mixed wood/heat pump heating configuration.
Benefit:
The main assumption is the COP.
Knowing the energy (kWh / year) for heating, the energy savings can be computed.

scenario 5:
move to double flux ventilation.
TBD

Note: it seems that these scenarios can be combined, and in this case the cost/benefit can be obtained by summing
the cost/benefit of each scenario.

So under the above assumptions, it seems that cost projections for these scenarios can be made based on the annual energy consumption of the house.