Occupant Related Energy Needs

Dwelling occupants generate energy needs related to their behavior which can be grouped in three categories :

• domestic hot water needs

• cooking

• specific electricity use (refrigerator, dishwashing, television, etc.)

In turn, part of the energy consumption related to these uses will be turned into heat which, together with the body heat produced by occupants, will contribute to the building heating needs.

Two modes of simulation are executed with differing objectives :

• conventional mode : occupants follow an identical and conventional behavior defined in energy diagnosis norms, independent of the type of occupancy, so that the resulting energy consumption can be used to determine the building energy class

• actual mode : occupant follow a stochastic behavior dependent on the occupancy type, so that that the resulting energy consumption can be compared to energy meter data

Domestic hot water needs

In conventional mode, the domestic hot water needs are obtained as a function of the conventional occupant count, itself a function of the living area using the model defined in the 3CL DPE method. Details are available p.68 of the 3CL DPE methodology

In actual mode, the daily domestic hot water use by occupant in liters is drawn in a beta distribution with parameters 2.5 and 4.5 and scaled to lie in the interval 10 liters to 150 liters. This distribution has been selected to fit the data from a national study of domestic hot water consumption.

Histogram of measured domestic hot water needs by occupant

The energy needs associated to the hot water consumption are then obtained by making the hypotheses that the water needs to be heated from the ground temperature to 40°C. Annual needs are obtained using the average ground temperature, while peak needs rely on the minimal ground temperature.

Specific electricity use

Specific use is not taken into account in conventional energy models as it is unrelated to building characteristics. In actual mode, the annual specific use by occupant is drawn in a beta distribution depending on the ‘residential_type’ :

Specific use beta distribution

residential type	min (in W)	max (in W)	a	b
house	900	3000	2.5	4.5
apartment	700	2600	2.0	4.5

The maximal specific use is selected depending on the number of occupant and residential type of the dwelling

Specific use maximal power (in W)

residential type	1	2	3	4	5	6
house	6000	6000	6000	6000	9000	9000
apartment	3000	3000	6000	6000	6000	9000

Cooking (experimental)

Cooking is the only significant specific use of energy that can be delivered by fuels other than electricity (mainly gas). However, we currently lack open data to determine which dwelling use gas a cooking fuel. To work around this issue, we currently use the fuel of the main heating system to define a probability of using gas for cooking and then affect a share of the specific uses to the gas consumption accordingly.

Attenuation with occupant count

Annual domestic hot water and specific energy use by occupant decrease with the number of occupants in a dwelling. To approximate this, we use a fictitious number of occupants :

\[FOC = OC^{1 \over 1.2}\]

where \(FOC\) is the fictitious occupant count and \(OC\) is the real occupant count.

Occupant gains

Occupant-related heat gains group together heat gains due to occupant body heat and occupant use of energy in the dwelling. In conventional mode, occupant-related heat gains are taken to be 70 Wh by day and by m² of living area. In actual mode, occupant-related heat gains are the sum of metabolic gains (average of 25 W by occupant) and 40% of the specific needs.

Impact of occupancy type

In actual mode, the annual domestic hot water and specific need are multiplied by an intermittency factor that represents the share of time occupants will be in the dwelling and that is drawn in a beta distribution whose parameters depends on the occupancy type (except for vacant dwelling where it is 0) :

Intermittency factor beta distribution

occupancy type	min	max	a	b
occasional housing	0.1	0.4	2.5	4.5
second home	0.05	0.25	2.5	4.5
house primary residence	0.75	1.0	4.5	2.5
apartment primary residence	0.65	0.95	4.5	2.5

In conventional mode, the annual domestic hot water needs are multiplied by an intermittency factor that depends on the residential type

Conventional intermittency factor

residential type	intermittency factor
house	0.95
apartment	0.85