Monitoring Results

Detailed energy monitoring and data analysis allow precise values for the energy balance of the building and hence gives a more realistic picture of the resulting primary energy consumption.

DHW consumption average = 17 kWh/m2a

specific heat supply

[kWh/m2a] ■ heat recovery and ambient heat consumption

100 average = 19 kWh/2a

On average annual 25 kWh/m2 net heated floor area are used for space heating, but in one extreme case a value Qheat =2 kWh/m2 net heated floor area was measured. Ambient heat and heat recovery cover 19 kWh/mP net heated floor area of the annual space heating. 17 kWh/mP net heated floor area are need to cover the hot water demand. Thermal losses of pipes and storage in the building average 11 kWh/mF. Figure 6 shows the heat consumption of all monitored projects. Not all projects have heat recovery or preheated fresh air for heating the air supply.

Figure 6 Total heat consumption and heat losses in the evaluated projects (related to net heated floor area)

The primary energy consumption is calculate as the sum for the total heating consumption (space heating, hot water and heat recovery)including heat losses and electricity for pumps, fans and controls. In the demonstration projects the average of the annual primary energy (PE) demand reaches a value of 53 kWh/mF net heated floor area, in some projects a minimum PE = 13.7 kWh/mFa. The primary energy consumption for other household appliances, e. g. lighting, cooking and other have a mean value of about 70 kWh/mFa. Figure 7 reviews the primary energy for the heating and ventilation systems as well as for household appliances. Only 40 % of the primary energy in the houses is used to cover the heating and ventilation demand and 60 % the other household appliances.

specific primary energy

consumption [kWh/m2a] ■ household appliances average = 70 kWh/m2a

200

total HVAC average = 53 kWh/m2a

Figure 7 Primary energy consumption for HAVC and other household appliances in the analyzed buildings (related to net heated floor area)

The best results were obtained in the semi-detached house in Monte Carasso, CH. This house has a very low space heating demand and less heating losses. Heat is supplied by wood pellet combustion and solar thermal collectors to support the hot water production. An exhaust air ventilation system is installed in the building. Fresh air intake is preheated via an earth-to-air heat exchanger.

Important for a high efficient building is the energy ratio ep which consider the sum of space heating, heat recovery (Qheat) and hot water (Qdhw) relative to the primary energy consumption (PE).

ep = (Qheat+QDHW)/PE

primary energy

[kWh/m2a] detached Bsemidetached Arow ^apartment

1.45 Durbach, ultra, D

120

1.52 Durbach, NEH, D

Figure 8 Relation between measured useful energy and the calculated primary energy of the analyzed buildings. If the factor of energy expenditure (Anlagenaufwandszahl) is lower than one, the energy supply system is very efficient (related to net heated floor area).

140

The factor ep, the amount of net space heating and hot water consumption related primary energy demand, will be less than one, if renewable energy replace some of the needed auxiliary energy. The primary energy factor for renewable energies is assumed as zero for thermal solar energy and very low for biomass and pv. Figure 8 shows the relation between primary energy demand and the net energy consumption for heating and DHW in the analyzed buildings.

Most of the buildings which use solar energy or biomass as well as having ground heat exchangers and ventilation heat recovery have a factor of energy expenditure lower than one and are very efficient. These are the buildings for the future.