Electric Energy Efficiency for Households – Doing the whole step towards energy efficiency

The consequent implementation of the Passive House Standard results in a drastic reduction of the heating energy demand for buildings. As a result the remaining energy consumption, of which the household electricity is a considerable part with an average consumption of more than 3000 kWh/a [E-NRW2015], should get into the focus of attention. The issue of electrical efficiency is generally hardly ever being discussed during the design or consultation process of new constructions or redevelopment projects. To really make a step towards highest efficiencies, the household electricity has to be considered.

On the way towards a renewable energy supply the implementation of highest energy efficiency is mandatory. In the context of residential buildings this holds for the building itself including heating and domestic hot water preparation. But it is not sufficient to stop at the building level. This is important, because, looking at the primary energy, in many cases the electric energy consumption represents the biggest remaining share on household level. Despite that low energy consumption is also to be aimed at for comfort reasons, e. g. to avoid overheating in the summer.

In the framework of the SINFONIA project the next step towards apartment level and the individual household energy consumptions could be taken. Therefore after the retrofit of the building was finished, tenants were offered a consultancy concerning their individual electricity consumptions including a personal consultancy and a measurement of up to 8 single appliances. During a personal meeting all household appliances were listed in a consultancy tool and the consumptions resulting from power consumption as well as frequency and duration of usage were estimated. To ensure that no larger consumers are forgotten the listing is compared with the last invoices.

Based on this, appliances or groups of appliances were selected to be measured. This way uncertainties concerning the estimated parameters could be reduced. A general assumption for the usage could lead in most cases to miss optimisations. This applies especially for white ware such as freezers, dish washers, washing machines and tumble dryer. Depending on the frequency of usage, which e. g. for the tumble dryer can vary between a few times per month to up to several times per day, investing in a new appliance can be absolutely not recommendable or highly profitable. Furthermore the usage and standby periods are recorded and the energy consumption for lighting and eventually existing preparation of domestic hot water can be taken into consideration.

electro-energy-efficiency

As a feedback the tenants got specific recommendations to reduce their electric energy consumptions. The most frequent recommendations were exchanging conventional lightning bulbs by LED, exchange the cooling devices and use switches to reduce stand by consumptions.

Conclusions:

During the consultancy of tenants living in refurbished buildings concerning their household electric energy consumptions potential savings of 30 % were found that can be realised economically.

Lessons learnt:

The consultancy of tenants concerning their electric energy consumptions evolved to be a meaningful step towards higher efficiency. The first hurdle was the activation of tenants for the topic which has to be done at best with personal communication. Receiving the first invoice for energy after the retrofit the tenants showed a high sensibility. So this is a good time to start the activities and to disclose reasons for high energy consumptions.

References:

[E-NRW2015]   Energieagentur NRW: Erhebung „Wo bleibt der Strom?“, 2015

O. Ottinger, F. Gressier, M. Hohm, S. Peper: Electric Energy Efficiency for Households: The next step towards the NZEB, Tagungsband 21. Internationale Passivhaus-Tagung, Passivhaus Institut Darmstadt, 2017.

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