BUILDING PROFILE CAPLIN HOMES – SOLAR HOUSE

Since our formation in 2008, the Zero Carbon Hub continues to work with Government and industry to create a zero carbon definition that can be delivered by the mainstream house building industry.

This series of building profiles gives examples of manufacturers, developers and clients who have embraced the challenge and are developing practical, commercially viable ways of delivering energy efficient, low carbon homes.

CAPLIN HOMES – SOLAR HOUSEBUILDING PROFILE

PROFILE: 001

MARCH 2015

DEVELOPER

Caplin Homes

ABOUT

Established 1970Focus on low carbon, energy efficient homes

COMPLETED

September 2013

Profile supported by

OVERVIEW__

SUMMARY

Built by a consortium led by Caplin Homes, the Solar House was constructed in 2013 as an exemplar project to demonstrate to members of the building sector that zero-carbon buildings are not just possible but are also affordable and economically viable.

SPECIAL FEATURES

The Solar House integrates a Fabric Energy Efficiency Standard (FEES) with a number of key technologies, including an array of hybrid solar panels (PVT), solar walls to pre-heat incoming ventilation air, and an Earth Energy Bank (EEB) and heat pump to store and retrieve heat collected in the summer months for use in winter. The combination of high fabric specification and low carbon technologies has dramatically reduced both running costs and CO2 emissions from the buildings energy use.

BUILDING PROFILE CAPLIN HOMES – SOLAR HOUSE

PROJECT STRATEGY__

KEY PLANNING CHALLENGES

DESIGN AND CONSTRUCTION

PRODUCTS AND SYSTEMS

FORWARD THINKING

The largest challenge faced by the Solar House in achieving planning permission related to its nature as a single dwelling in a rural landscape. Under paragraph 55 on the National Planning Policy Framework (NPPF) the development had to show its innovative nature and high build standards. With strong support from Harborough District Council planning permission was granted in December 2012.

Another key consideration during the planning stage was the sites elevated nature. Due to the design and construction methods of the Energy Earth Bank System any significant future change in rainfall or ground water retention may have negative impacts on both the system and building's energy performance. By constructing the home on an elevated site it is hoped this potential future issue can be avoided.

CONSTRUCTION

To ensure the quality and energy performance of the home, it was decided to construct the Solar House through offsite manufacture using closed timber frame panels. By using a timber frame structure, manufactured under factory controlled conditions, it was hoped that the development would be able to more accurately ensure the consistency and build quality. This in turn helping to reduce any potential performance gap between the design and as built energy performance.

Despite the use of offsite construction methods, progress on the development; during the earlier blockwork phase, was delayed on site for one month during March 2013 due to exceptionally harsh weather conditions.

CULTURE

To further guarantee quality on site Caplin Homes employ a team of sub-contractors specialising in low energy buildings, who are trained by the developers and systems manufacturers to deliver the homes to specified standards with minimal supervision.

A number of innovative building systems were incorporated into the Solar House. These include the integration of:

O SolarWall – Passive ‘outer skin’ which uses thermally conductive material and perforated steel sheets to pull preheated air into the buildings ventilation system.

O PVT Panels – Advanced solar energy capture, generating both electrical and thermal energy, using HYBRID PV-T panel arrays.

O The Energy Earth Bank system (EEB) which uses 56 boreholes – 1.5m deep beneath the building – to store solar energy captured in the summer for use in the winter period.

One of the project's key considerations was to demonstrate that the technologies incorporated in the Solar House could be applied to more ‘mainstream’ housing designs and non-domestic builds. To ensure this, the Solar House was modelled thoroughly and monitored extensively throughout its development process and into occupancy.

A further 12 sites incorporating the Solar Homes Zero Carbon technologies are under consideration or are currently being monitored. By 2017 these sites will have provided additional evidence as to the extent of the systems performance and viability.

BUILDING PROFILE CAPLIN HOMES – SOLAR HOUSE

PROJECT SOLUTIONS__

AIRTIGHTNESS AND VENTILATION

To help reduce any potential air leakage the Solar House employs a robust airtightness strategy in its construction.

O Insulation in each frame is sealed to the inside edge;

O All frames being sealed to their neighbours;

O Multifoil wrap taped to each seam to form an impermeable membrane;

O Plaster board and skim to form a final barrier.

While these processes aim to reduce leakage in the homes structure, further seals, such as around LED lights and structural openings, must be addressed separately and checked regularly throughout construction.

The Solar House concept uses MVHR linked to the SolarWall system. This system provides pre-heated air to the whole building while extracting stale/moist air from specific rooms.

SPACE AND DOMESTIC HOT WATER (DHW)

Space and domestic hot water in the Solar house is supplied through the integration of the energy efficient technologies in the home. Sensors linked to the PVT panels, DHW boiler, heat pump and under floor heating (UHF) all monitor temperature and redirect energy flows to maintain predetermined levels.

When the temperatures of DHW and space heating systems are lower than the set point, energy is taken directly from the PVT array or the EEB to raise the temperature to the desired point.

Where sensors indicate that levels are currently being met, energy produced by the PVT array can instead be directed through the EEB pipework to store the energy for use in the future.

Throughout any given day energy will flow back and forth from the EEB as Space and DHW demand changes, as well as, in response to external temperature and weather changes.

1280

2400

x900

1940

2400

x900

2909

1566

140

1140

140

1568

3844

2400x900

1345

600x1050

1280

4500

2350

x240

0

150

4500

2350x2400

150 150

2350

x240

0

1205

1699

x240

0

215 4250x2400 286

150

2350x2400

1205

1699x2400

2448

5008

1115

823

4016

890x

2100

616

4400

2442

8352

4400

1089

1225

636

890x

2100

4076

134

890x

2100

1210

2954

5591

3836

2793

2342

4635

5539

2470

600x1050791

890x2100

3782

1796

890x

2100

107

2400x600 1140

600

x105

0

1010

3508

1698

890x

2100

936

4412

2793

1128

890x

2100

962

3434

890x2100311

3446

2305

4412

495

860

29762418

1303

2514

2814

909

873

1754 890x2100 1754

2419

1815

First Floor PlanA

A

B

B

3380

C

1995

PART L 2010

Fabric Energy Efficiency Standard

TARGET

46 Kwh/m2/yr

ACHIEVED

44.1 Kwh/m2/yr

PART L 2010

Carbon Emissions

TARGET

25.60 kgCO2/m2/year

ACHIEVED

0.32 kgCO2/m2/year

Heating System Specification

SOLAR PANEL AREA

38.3 m2 at 20°

ENERGY STORAGE

56 Bores 1.5 deep 1.5m spacing

GROUND SOURCE

HEAT PUMP

DOMESTIC HOT

WATER BOILER

WALLS

U = 0.14 W/m2K140mm Framework, 100mm PU Foam Insulation, Multifoil Insulation, 250mm External Wall Thickness

PLAN

AIRTIGHTNESS

2.9 m3/m2h at 50 Pa (tested)

VENTILATION

90% MVHR Efficiency

ROOF

U = 0.11 W/m2K 150mm PU Insulation, Flat Roof Construction

WINDOWS

U = 0.78 W/m2K Whole window Triple Glazed / Timber and Aluminium Frame

THERMAL BRIDGING

y = 0.085 W/m2K FLOOR

U = 0.20 W/m2K

BUILDING PROFILE CAPLIN HOMES – SOLAR HOUSE

KEY LESSONS__

DESIGN, CONSTRUCTION AND COMMISSIONING STAGE

POST OCCUPANCY EVALUATION / DEMONSTRATING PERFORMANCE

PROJECT PARTNERS

CONTACT CAPLIN HOMESZERO CARBON HUBLayden House 76-86 Turnmill Street London EC1M 5LG

f 0845 888 7620

a info@zerocarbonhub.org

B www.zerocarbonhub.org

f 0116 259 3591 a info@caplinhomes.co.uk

B www.caplinhomes.co.uk

Due to the Solar Houses offsite construction methods and trained labour force, a large number of potentially problematic areas for this development were avoided. This was particularly evident when considering the Solar House insulation, where the pre-filled, closed time frame panels ensured the correct level and proper installation of a key element in the homes low energy strategy. The manufacturing methods of these panels also allowed the development to continue at a steady and accurate pace.

However issues linked to the placement and number of sensors installed to monitor various components and post occupancy evaluation criteria was noted. Attention was drawn to both a lack of sensors in some areas, as well as, an over allocation in others. Knowledge learnt from this experience has now been accumulated to avoid similar problems in future developments.

Minor issues were also identified with operation of the homes SolarWall MVHR system, where consistent checking of filters was not regularly undertaken after the commissioning stage, resulting in a build up of foreign materials reducing the systems effectiveness, although reversible this issue re-emphasises the need for energy efficient systems to be operated correctly with robust maintenance processes in place.

PERFORMANCE

Since construction the Solar House has been monitored through two winters and a summer period. The observations made in this period indicate that all the systems in the home seem to be performing well.

O The year-on-year performance has been remarkably consistent with only a 0.3ºC difference for any period over the two winters. Showing that even in varying conditions the EBB is able collect and store energy effectively for use in colder periods.

O Monitoring of the home has also shown the EBB to be robust, with peak ground temperatures (9ºc) being maintained for use throughout the winter period. This allows the home to continue to withdraw energy from the EBB for use in the house despite surrounding ground temperatures dropping below 0ºC.

O The electricity generated over the first 12 months was 6,400 KWH equivalent to 1,185 KWH per 1KWp of capacity, confirming the beneficial effect of

cooler PV operating temperatures. This also amounts to around twice the energy needed to run the heat pump.

In order to guarantee the performance of the Solar House occupant controls were also limited to a single display where only room temperature could be altered.

OCCUPANTS COMFORT/PERSPECTIVE

Only one area of concern was noted with the performance of the Solar House. This was associated to a number of large unshaded windows on the south side of the home, which caused overheating prior to occupation of the building. In order to increase resident comfort and choice the method of rectifying this issue was ultimately left to the future occupiers, who eventually, with the help of the developer, chose to fit automated internal blinds with a high reflective rating.

Lessons relating to solar gains and the risk of overheating in highly energy efficient homes were taken onboard and applied to the design of future homes.