Innovative solution for heat recovery of ventilation air in older apartment buildings - with low intervention affecting the residents

Transcription

1 Innovative solution for heat recovery of ventilation air in older apartment buildings - with low intervention affecting the residents

2 Innovative solution for heat recovery of ventilation air in older apartment buildings - with low intervention affecting the residents Björn Berggren *1,2 Henrik Davidsson 1 1 Lund University, Energy and Building Design, P.O. Box 118, Lund, Sweden 2 Skanska Sverige AB, Skanska Teknik, Malmö, Sweden

3 Agenda Introduction and objective Method Results Discussion & Conclusions

4 Introduction Reduced energy use in buildings is an important strategy for climate change mitigation Post WW II buildings, large share of the building stock in Europe In Sweden, roughly 40 % of the dwellings, ~ , are in multifamily buildings constructed Average pace of new construction, dwellings/year

5 Introduction Why heat recovery? Natural ventilation and exhaust air ventilation in the Swedish dwelling stock seldom recover any heat from outgoing air» High energy demand for heating» Reduced thermal comfort Mechanical ventilation with heat recovery reduces energy demand for heating and increases thermal comfort

6 Introduction Previous renovation projects with reduced energy use for heating >50 % installed mechanical ventilation with heat recovery Photos: Arkitektskap AS and SINTEF Building and Infrastructure Photos: Ulla Janson Photo: Thyholt, M., & Slagstad, H. Foto: Skanska Sverige AB

7 Objective Investigate potential for heat exchanger suitable for natural ventilation, exhaust air ventilation and hybrid ventilation Previously described in: Davidsson, H., Bernardo, R., & Hellström, B. (2013). Hybrid Ventilation with Innovative Heat Recovery A System Analysis. Buildings, 3(1), , pp. 13. Davidsson, H., Bernardo, R., & Hellström, B. (2013). Theoretical and Experimental Investigation of a Heat Exchanger Suitable for a Hybrid Ventilation System. Buildings, 3(1), 18-38, pp. 21.

8 Method Qualitative and quantitative comparision of different ventilation systems: Mechanical Exhaust air Ventilation system, MEV (common in the existing building stock) Balanced, Mechanical, Ventilation with Heat Recovery, MVHR (traditional solution for recovering heat from the outgoing ventilation air) Innovative solution for Heat Recovery, IHR

9 Innovative solution for Heat Recovery, IHR

10 Results Potential Dwellings in Swedish multifamily buildings by year of completion and region [SCB, 2011].

11 Results Potential 100% Share of dwellings 50% 0% A B C D Longitudinal Transverse Pillars No record/other Left: Distribution of dwellings in different types of multifamily houses in different regions Middle: Distribution of number of floors in dwellings in multifamily houses in different regions Right: Distribution of load bearing systems in dwellings in multifamily houses in different regions A: Sweden, excluding metropolitan regions B: Stockholm region C: Göteborg region D: Malmö region [SCB, ].

12 Results Potential Left: Distribution of dwellings with different types of ventilation, results from field studies; BETSI Right U-values for exterior walls and roofs, comparing requirements in building regulations and results from field studies; BETSI [Boverket 2010].

13 Results Qualitative comparison MEV Strengths Low volume needed for ducts Well known technology Weaknesses No heat recovery No preheating of inlet air MVHR IHR Well known technology High thermal comfort Reduced space heating demand Low volume needed for ducts Low electricity consumption Reduced space heating demand High electricity consumption for fans Increased need for ducts Increased maintenance New technology Hard to combine with noise dampers & filters

14 Results BC Conditioned area [m 2 ] 1200 Window-wall-ratio [%] 20 Air exchange rate [h -1 ] 0.5 Geographic location Stockholm, Sweden Ventilation system MEV MVHR MVHR IHR IHR Heat recover/sfp [%, kw/m 3 s] -/0.5 80/ / /0.5 75/0.5 Exterior walls, U-value [W/m 2 K] Roof construction, U-value [W/m 2 K] Windows, U-value [W/m 2 K] Air tightness (EN 13829) q 50 [l/s, m 2 ] Slab on ground, U-value [W/m 2 K] 0.30 Thermal bridges Included in U-values Interior floor slabs 200 mm reinforced concrete

15 Results

16 Discussion and Conclusions Existing building stock in Sweden: Built outside of metropolitan areas 3-4 stories high Slab block building, ~50/50 % with longitudinal/transverse load bearing systems respectively Natural ventilation or Mechanical exhaust air ventilation.

17 Discussion and Conclusions Energy savings: Big energy savings if IHR or MVHR is combined with measures for the building envelope IHR would be preferable if electricity is valued higher compared to MVHR Renovation should also include measures for domestic hot water, plug loads and lighting This study focused on energy savings Be aware of moisture safety, indoor air quality, fire safety etc.

18 Thank you! Questions? More questions? Visit exhibition both 3