Practices

Vallda Heberg: a Swedish certified passive house residential area

A Subliniat Caz August 2016
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Vallda Heberg is a residential area in Sweden where all of the buildings are designed, built and certified according to the Swedish passive house standard. The national standard includes specific construction elements in the building design, such as well insulated buildings with airtight envelopes and supply and exhaust ventilation with heat recovery in all buildings.  These elements contribute to a very low overall energy demand.

 

The area is comprised of 26 single family dwellings, four multi-family dwellings (4 apartments per building), 6 row (terraced) houses with 22 units, and a retirement/nursing home for elderly people with 64 apartments including a shared living area and two commercial spaces. The small amount of energy needed for space heating and domestic hot water in these buildings is supplied by 100% renewable energy generated on site and distributed in a local district-heating network. The goal is that as much as 40% of the annual energy use for domestic hot water and space heating will come from solar thermal collectors, whilst the remaining 60% (mainly during the cold season) is supplied by a central wood pellet boiler.

 

The idea to build efficiently right from the beginning in such a large scale design phase is unique and brings on a whole new way of thinking as well as large interdisciplinary collaborations. After construction, the performance of the passive houses has been evaluated through measurements and occupant surveys. The Vallda Heberg project shows that it is possible to build an energy-efficient residential area without compromising on a good indoor comfort.

 

The case study focuses on a typical single family dwelling or SFH (Single-Family House).

 

 

 

Location

 

Vallda Heberg neighborhood: Heberg, Vallda, Kungsbacka municipality, Halland Country, Sweden

Detached single-family house case study: Guldvingevägen (19 houses) and Nätvingevägen (7 houses), 434 90 Vallda, Sweden

 

 

 

Project team

 

Contractor (including project management): NCC Construction Sweden AB

Real estate owner: EKSTA Bostads AB - Municipal housing company

Consultants:  Markgren Arkitektur AB, Mats Abrahamsson Arkitekter AB, NCC Environment, Andersson & Hultmark and BA-Elteknik.

Collaboration:  end users, Kungsbacka municipality

 

 

Time schedule

 

Design: n.d.

 

Construction: 2011-2016

 

The construction of Vallda Heberg started in 2011 and the last building was completed in 2016.  The two commercial buildings (contain office space, a gym and a bakery) were completed in the summer of 2014.

The detached single-family houses were fully occupied by the beginning of 2013, while the apartment blocks, the terrace houses and the retirement home were fully occupied by the end of 2013 / beginning of 2014. The last building, the shared living area, was completed and occupied in September 2016. 

 

The residential area was to be developed over a two year period. The Single family housing (SFH) was occupied by the end of 2012, while the other buildings were to be occupied in late 2013. The heat supply system, including solar collectors, was put into operation in steps in order to supply heat to the buildings as they became occupied.

 

 

Building use and area

 

The building area and floor layout varies between the different residential houses and apartments.

 

The total floor area of the single family house is 140 m2 divided between two floors.

The standard model of the single-family house is comprised of a first floor with a kitchen, living room, laundry room and a toilet. On the second floor there are three bedrooms, a bathroom, a walk-in closet and a small living room. There is also a glass-enclosed vestibule that functions as an extra hall in the entrance way as well as a carport with a storage room in close connection to the building.

The layout of a single-family house is shown in the pictures, the dash-lined walls on the first and the second floor are optional walls that are not built in most of the houses in Vallda Heberg.

 

 

 

Construction costs

 

Global project cost: The final sum for NCC’s contract work was 38 M€ (excluding VAT, using an exchange rate of 9 Sek/€). This included the costs for all passive houses in the area, renewable energy system solutions as well as design and groundworks.

 

Single-family houses: The total costs for one detached single-family house was approximately 190 k€ (excluding VAT, using an exchange rate of 9 SEK per €), of which 13% was estimated to be additional costs for the energy efficiency measures. The total cost per m2 is estimated around 2,450 € (including VAT and taxes), only 10% higher than a regular Swedish single-family house.

 

Project funding: This project was funded with 21-23% of investment cost for the installation of solar collectors. Also, financial support has been received from SBUF (the Swedish construction industry's organisation for research and development) and as a LÅGAN demonstration project (a Swedish programme for buildings having very low-energy use).
Additional financial support from SBUF (the Swedish construction industry's organisation for research and development).

 

 

 

Envelope performance

 

For the different types of residential passive houses, there are various technical solutions, one example being the insulation materials as well as the thickness of wall insulation.

The structural system of a single family house has loadbearing timber stud walls with a timber roof truss structure on top. There is mineral wool insulation in the walls and the roof is a cold attic with blow-in wool insulation. The foundation is a concrete slab on the ground and the slab between the two floors is built with light weight composite timber beams.

 

U-values of the main elements in a typical single family house:

 

Element

W/m2K

External walls

0.106

Ground floor

0.08

Roof

Attic floor

0.07

0.055

Windows (frames included)

0.75

External entrances and balconey doors (frames included)

0.7 - 0.8

 

 

Other details:

-The timber stud walls have been insulated with 29 cm thick mineral wool and 8 cm of glass wool (U=0.11 W/m²K), while the roof has 60 cm blown wool (U=0.07 W/m²K). The house has triple-glazed windows.

-The balcony and the carport are designed to be used as solar shading for some windows on the first floor. The facades are made of a horizontal timber panel.

The glass-enclosed vestibule functions as a ¨breezeway¨ (standard U.S. term) and reduces heat leakage when doors are opened.

 

 

Energy use

 

Expected energy performances of the passive houses are based on calculations performed in the simulation tool IDA Indoor Climate and Energy (IDA ICE) by the contractor NCC. The specific energy use, including property electricity (for buildings services) and energy used for space heating and domestic hot water, is presented for four types of residential buildings in the table below. For the detached single-family houses, the calculated specific energy use (60 kWh/m²/year) includes space heat demand (39.2 kWh/m²/year), property electricity for buildings services (5.6 kWh/m²/year) and domestic hot water (15.4 kWh/m²/year).

 

 

Detached single-family houses

Terrace houses

Apartment blocks

Retirement home

Specific energy use (kWh/m²/year)

 

60

 

59

 

52

 

51

 

 

 

The measured energy use is presented in one of the pictures above. Note that washing machines and dishwashers in the passive houses use domestic hot water. According to Swedish building regulations, the energy used for appliances is part of the household energy and not of the specific energy use. This means that the specific energy use is a bit lower than the values presented in the pictures.

 

 

 

Monitoring results in a typical single-family house (based on the first measurement in 2013):

 

Uses

Final Energy (kWh/m2year)

Systems

Primary Energy (kWh/m2year)

Heating

33

Solar energy

0

Hot water

17.6

Biofuel

30.4

Cooling

0

Wind energy

0

Ventilation

5.1

 

 

Lighting

n.d.

 

 

Electrical appliances

n.d.

 

 

Total

55.7

Total

30.4

 

The project shows a very good conformity with the calculated values at the planning stage and the residents were very satisfied with the indoor climate as well (see attached reports for more information)

 

 

Total production of Solar Thermal (2013):

 

 

Heat (kWh/y)

Units

Solar collector area (m2)

Total (kWh/y)

Sub Station 1

7,800

19

142

148,200

Sub Station 2

7,800

7

38

61,600

 

 

 

The case of single-family houses compared to the national energy performance requirements is 51% (the National Board of Housing (BBR) Maximum specific energy use is 110 kWh/m².year for this region in Sweden, according to BBR18 requirements).

 

 

 

Energy systems

 

Heat recovery system

 

The buildings are all equipped with a heat recovery unit. There is a hot water circuit inside the buildings which is used not only for space heating (there is a heat exchange with a glycol circuit that supplies the heating coil in the air handling unit with heat) and for comfort heating in the bathroom floor, but also for domestic hot water. In all buildings, the washing machines and the dishwashers are connected to the domestic hot water.

 

Heat generation and distribution system for space heating and DHW

The energy needed for space heating and domestic hot water in the residential area is supplied by 100% renewable energy generated on site. Heat is generated in a 250 kW central wood pellet fueled boiler (backed up by an oil fueled boiler) and from solar thermal collectors of two different types: 570 m2 flat plate collectors (located on substations and roofs) and 108 m2 evacuated tube collectors (mounted on the boiler). The goal is that as much as 40% of the annual energy use for domestic hot water and for space heating will come from the solar thermal collectors.

 

A small local district-heating system is used to distribute heat from the generation units to the passive houses. The distribution system consists of a primary and a secondary system. The primary system is a well-insulated district-heating system with supply and return pipes, delivering heat from the boiler and from the evacuated tube collectors to four substations located throughout the system, as shown in one of the pictures. In the substations there is an input of solar heat from the flat plate collectors located directly on substations and on other buildings in the area. Heat is exchanged within the substations to the secondary system, which is a domestic hot water circuit providing the passive houses with both domestic hot water and heat for space heating.

 

 

 

Awards and recognitions

 

Nominated as the construction project of the year in Sweden, 'Årets bygge' 2013 (http://byggindustrin.se/arets-bygge-2013).

 

One of the single-houses is described as an example of nZEB inside the detailed report “Selected examples of Nearly Zero-Energy Buildings” disseminated by EPBD-CA (http://www.epbd-ca.eu/wp-content/uploads/2011/05/CT5_Report_Selected_examples_of_NZEBs-final.pdf).

 

 

Additional Information

 

Case study in several EU projects:

 

 

 

 

 

 

 

Lessons learnt

The measured energy performance is very close to, and even better than the expected energy performance. According to a questionnaire survey, the residents are very satisfied with the indoor climate.

Award labels

Additional documents

Available link languages

Start date - End date

Duminică, 1 Ianuarie, 2012 to Miercuri, 31 Decembrie, 2014

Source of funding

Funding description

Financers of the evaluation project: LÅGAN – a collaborative project between the Swedish Construction Federation, the Swedish Energy Agency, Region Västra Götaland, Formas and others; SBUF – the Swedish construction industry's organization for research and development; NCC and Eksta Bostads AB.

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