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With respect to space heating, the Maryville Passive House is a ‘Zero Carbon’ home.

The Concept

The Maryville Passive House is a continuation of research by Joseph Thurrott Architects into the reinterpretation of Scottish rural vernacular buildings to meet modern low-energy demands. Maryville is articulated as two volumes to accommodate a larger footprint whilst maintaining the proportion of familiar 6m wide gable-ended buildings found throughout the Scottish countryside.  A double-height, open-plan living room with a high efficiency wood burning stove at the centre, serves as the focus of the house.  The majority of the south elevation is composed of windows, permitting an abundance of direct sunlight into the heart of the home.  This passive solar energy provides 60% of the annual space heating.

Fabric First

With an average U-value of 0.10W/m²K, the factory insulated Scotframe Val-U-Therm® timber frame superstructure is supported on in-situ concrete strip foundations. An insulated concrete ground bearing slab provides thermal mass.  The superstructure is wrapped in a continuous thermal skin of closed cell insulation boards, faced predominately with a proprietary render system with timber cladding to the south elevation.  The roof is clad in standing seam zinc sheets with photovoltaic and solar thermal panels to the southern slope.  All windows and doors are timber framed, triple glazed with argon/krypton gas fill.  The Val-U-Therm® envelope is meticulously detailed to mitigate thermal bridging (Ψ≤0.01W/mK) and achieves an average air tightness performance rating of 0.486 air changes per hour sat 50 Pa

Energy Efficiency

Maryville is designed to the Passivhaus standard; hence, the total annual energy demand must be less than 120kWh/(m²a).  To achieve this target, the spatial planning maximises passive solar heat gain.   In addition, the Scotframe Val-U-Therm® external envelope is highly insulated, air-tight and thermal bridge free. The internal environment is controlled by a Mechanical Ventilation Heat Recovery system which distributes fresh, pre-warmed air throughout the house 24 hours a day. The combination of the above provides sufficient space heating to maintain a comfortable indoor environment for approximately 8 months of the year without the need for an additional heat source.  During the winter months, space heating is provided by a wood burning stove.  With respect to space heating, the Maryville Passive House is a ‘Zero Carbon’ home.

Hot water and electricity are predominantly generated by roof mounted solar collectors.  A supplementary electric immersion heater in the hot water storage tank serves as a backup source for hot water generation.  Mains electricity is used as a backup source for power in the home.  To date, Ian and Mary have generated more electricity from the solar PV collectors than they have consumed from the mains.  The Maryville Passive House is a net power supplier.

Space Heating Demand statistics for the first year of occupation:

Appliance                                 Contura 750 wood burning stove

Nominal output                         5 kW

Efficiency                                 80%

Fuel                                          log wood: stacked, air dry, 20% MC, mixed species

Energy density of fuel:              1,400 kWh/m3* – 2,000 kWh/m3

Data source: BIOMASS Energy Centre

Annual fuel consumption:          2.19m3

1400 kWh/m3*(2.19m3) =

3066 kWh(80%) =

2453 kWh

Heating energy demand             2453 kWh / 168.7m2 =

                                                 14.54 kWh/(m2a)

* The Calorific value of the wood is based on a minimum moisture content of 20%.  Air seasoned wood in the West Coast of Scotland climate region will most likely have a greater moisture content at the end of the seasoning period than other, drier regions in the country.  Hence, the lower Energy Density per volume figure is used for the calculations.

The Primary Energy Demand statistics for the first year of occupation:

Annual Electrical Energy Use (from quarterly bills)

25.02.13 to 29.05.13 =   1172 kWh

30.05.13 to 28.08.13 =   374 kWh

29.08.13 to 26.11.13 =   703 kWh

27.11.13 to 24.02.14 =   1128 kWh

Total mains electrical energy consumption from grid =3377 kWh

Total annual electricity generation through PV array =3001 kWh

Total annual electrical energy consumption =6378 kWh

Annual primary electricity demand

3377kWh(2.7) Primary Energy Factor for mains electricity =9117.9 kWh

3001kWh(0.7) PEF for PV electricity =2100.7 kWh

Total =11218.6 kWh

Total primary electricity demand =11218.6 kWh / 168.7m2 (TFA)= 66.50 kWh/(m2a)

Heating energy demand multiplied by the Primary energy factor for wood:

14.54 kWh/(m2a)(0.2)= 2.90 kWh/(m2a)

Total Primary energy demand (2.90+66.50) = 69.4 kWh/(m2a)

For over 24 years Scotframe have been providing their self build customers with a unique one-stop shop service, not only for the manufacture and delivery of your timber frame kit, but also the supply of windows, external doors, insulation, plasterboard, stairs, internal door sets, architrave, skirtings and finishings.

Scotframe manufacture Val-U-Therm, a highly innovative closed panel, factory insulated timber frame system which meets future building regulations today, will dramatically reduce the space heating energy costs in your new home and could even do away with the need for a traditional central heating system.

You can select from both their Homes Portfolio range of standard house styles and the Rural Homes Collection or as they do with many of their customers, they are happy to supply a kit package for a bespoke design from your own architectural drawings.

Scotframe have manufacturing and customer service facilities based at Inverurie in Aberdeenshire and Cumbernauld near Glasgow with regional sales offices and product display facilities in Dundee, Inverness, Brighton and Paignton.

Scotframe will ‘Thermally Engineer’ your project to ensure the most practical and cost effective thermal solution is specified.

You can see more Scotframe videos on their YouTube channel here.

Proud to exhibit at the Homebuilding & Renovating Shows. Scotframe manufacture Val-U-Therm, a highly innovative closed panel, factory insulated timber frame system which meets future building regulations today, will dramatically reduce the space heating energy costs in your new home and could even do away with the need for a traditional central heating system. You can select from both their Homes Portfolio range of standard house styles and the Rural Homes Collection or as they do with many of their customers, they are happy to supply a kit package for a bespoke design from your own architectural drawings.