News
November 19, 2013

Polish seminars – Part 2: Per Kempe´s practical experience with SVEBY

The starting point for SVEBY is to meet the energy demands of an agreement between the developer and the contractor based on the use of standardised occupant input data for energy calculations and how the verification of energy performance is done in buildings. The purpose is to use the standardised occupant input data (measured energy use) in energy calculations which needs to be adjusted if deviations occur in occupant behaviour, and that the calculation results apply to a “normal” Swedish conditions.

Per Kempe says: “It is very important that the calculations are updated when the building is completed so that all changes are included, and that it clarifies which version of calculation and input data the verification measurements are compared to. The SVEBY instructions apply primarily to new buildings (mainly residential and office), made with today’s technology, but can also be applied in parts to other types of buildings or major renovations.”

The example from standardised occupancy input for offices shows the following parameters: interior temperature set up in winter 21ºC and in summer 23ºC, air flows 1,3 l/s.m2, solar shading factor 0,5 in total (0,71 for fixed and movable protection), the occupant electricity energy as years standards equals to 50 kWh/(m2.a) and domestic hot water equals to 2 kWh/(m2.a), internal load is 100% usable and the personal heat is included as number of people (20 m2/person) with working hours as 9 hours per a work day and heat from a person of 108 W.

To achieve Green Building certification, a building must be 25% better than building code or when renovating at least 25% better energy performance after renovation with the good indoor climate. In some cases there are large penalty payments on the contractor if the building does not achieve Green Building certificate and its two year follow up.

“For verification of energy performance and installation system performance (for a twelve month period within 24 months after finishing building), there is great importance for data collecting to be running when the building is operational. Normally a new commissioned office building uses 10-15% more energy than calculated, but after year of fine-tuning the energy use can be 5-10% below the calculated energy performance.”

The example of a follow-up of a building shows that the simulated & designed energy was 85 kWh/(m2.a) (requirement by Green Building code was 88 kWh/(m2.a) respectively), and the energy monitoring showed that the actual energy consumption was  95 kWh/(m2.a) (and respectively 89 kWh/(m2.a) required by Green Building) and after a year of fine-tuning the building has achieved 81 kWh/(m2.a)  (and required by Green Building was 88 kWh/(m2.a) respectively).

“Problems that increase the energy use in office buildings can be: malfunction of ventilation heat recovery system, distribution loses from piping network, error in extended operation of air handling unit, set points for heating and comfort cooling are set up too close , subsystems are not communicating correctly with each other, or design errors (system running more than office hours).”