IEA HPP Annex 28 Calculation of compact units Workshop IEA HPP Annex 28 8 th International Heat Pump Conference, Las Vegas, 30 May 2005 Thomas Afjei, Institute of Energy, University of Applied Sciences Basel IEA HPP Annex 28 N 140

2 Outline of the presentation  Introduction compact units  System layout of compact units  Approach for the calculation

3 Introduction compact units  Background  In low- and ultra-low energy dwellings, significantly reduced heating energy requirement  Air-tight buildings => usually equipped with mechanical ventilation system with heat recovery  Share of domestic hot water energy requirement increasing up to 50% (ultra-low energy houses)  High insulation and high passive solar gains => eventually comfort cooling demand in summertime

4 Conclusion system layout  Compact unit  Highly integrated system layout with core elements  Heat pump  Domestic hot water storage  Ventilation heat recovery system  Optional solar collector  Air heating systems and/or systems with hydronic distribution  Optional cooling function in summertime

5 Principle of system layout Source: Viessmann

6 Consequences calculation  Heat recovery Energy requirement:  Reduction of energy demand by recovery of ventilation losses  Electrical expense for the operation of the ventilation system Source temperature:  heat recovery influences source temperature of the heat pump  ground-to-air heat exchanger influences source temperature

7 Assumptions calculation  Operation Heating energy requirement is covered in the order: 1. heat recovery (running through in the heating period) 2. heat pump 3. back-up heater Domestic hot water energy requirement is covered in the order: 1. solar collector (optional) 2. heat pump 3. back-up heater

8 Additional input data for compact units  Heat recovery:  key value: temperature change coefficient temperature difference outside-supply air temperature difference return-outside air  OA = Temperature change coefficient  mass flow rates  electricity input for ventilation

9 Additional input data for compact units  Solar energy system:  solar collector characteristics, meteo data  Ground-air heat exchanger:  outlet temperature (if not already considered in performance characteristics, see testing method HTA Lucerne)

10 HP calculation method compact units ambient dry bulb temperature [°C] OP 2 OP 1  heat recovery  Reduction of heating energy requirement  lower inlet temperature to heat pump Upper ambient temperature for heating OP 4  Domestic hot water covered by heat pump and back-up  domestic hot water energy requirement partly covered by solar contribution (optional) BU OP 3 design outdoor temperature Balance point temperature HP Space Heating DHW HR HRHR S S S  Heating requirement covered by heat pump and back-up BU Design indoor temperature

11 Thank you for your attention!