Sustainability
and other technical specifications
Photovoltaic energy
Technical Spec
2 x AxiTec AxiStorage Li 9S Lithium Ion batteries with total 312 Ah capacity
15 × 5kW solar panels from AxiTec, roof mounted as two separate arrays
1 x Sunny Island 8.0H with wireless communication
1 × 5kW SMA Sunny Boy solar inverter with 2 x isolator switches
All our energy needs are supplied by the abundant sunshine of Greece. There are 15 panels with room to expand the array if required.
The system can accept a generator if required, but we have never felt one was needed. There is also local mains power supply which could be connected by a qualified electrician to supplement the PV energy system.
The system was installed in November 2017 and shows no reduction in capacity.
Mains water and drainage
Technical Spec
We benefit from mains water from the limestone mountains that are a beautiful feature of central Lefkada
The sewage outlet from the toilet is routed by drainage pipes designed and installed by a UK registered plumber and as a result, toilet paper can be safely flushed. There is very little mains drainage in village Greece, so almost all properties have a ‘soakaway’ system buried in the garden where the water and nutrients can feed the soil. There is no odour with this system, and no need to have the soakaway pumped out.
The house has been built with two separate systems to maximise the capture of used water for the benefit of the garden.
Soiled washing-up water from the kitchen is designated ‘black water’ and is routed to the soakaway.
The second system deals with ‘grey water’ drainage. Lightly-used water from the shower and sinks and washing machine is fed directly into the garden to hydrate an area of trees and flowers.
Rainwater management
Technical Spec
When the rains come, they refresh and rehydrate the thirsty land, everything turns green and wildflowers erupt in profusion. We capture all the rainwater we can and re-direct the rest away from the house.
Rainwater from the roof is channelled through downpipes into various rainwater capture tanks placed discretely around the garden, in excess of 10,000 litres. This water is used for garden watering by gravity feed and to top up the pond.
Construction
The house construction actively takes account of rainwater in three ways.
The entire build is surrounded by a ‘French drain’, a gravel-filled trench with a sunken perforated pipe which collects rainwater and directs it away from the house plateau and into the garden below.
The straw bale walls of the house are seated on top of a robust ‘stem wall’ of masonry that rises 40-90cm off the ground. This stone base, together with the roof overhang, prevents any rainwater splash on the lime plaster.
The lime plaster is deliberately rough-textured. Three coats of lime plaster, each at least one centimetre thick, have been applied directly onto the bale walls by hand, to create a knobbled texture that forces rainwater to drip away from the surface. Our annual re-application of lime wash on all external walls for the first 10 years has contributed to their ability to repel water.
Winter heating
Wood-burning stove
Lefkada island is full of olive groves. At one time, families planted as many olives as they had room for. Greek olive tree management includes regular pruning, as olives prefer to bud on new growth wood. This creates a sustainable source of very high quality wood for heating.
We installed a wood-burning stove with an integral baking/roasting oven to maximise the efficiency of our heating.
Technical spec
The stove is a Heta Scan-Line 1000 B. It has a room heat output of 7.7 kW with an energy efficiency of 86%. It has a variety of approvals* ensuring it is made of quality materials, minimum environmental impact and with an optimum fuel economy. We find that only a few logs are needed to warm the entire house.
In addition, the house has a south-facing sun room that warms to over 30 degrees on a sunny day in winter. With the double doors open, the warm air flows into the house and is held by the impressive insulation in the walls.
*EN13240, NS3058, NS3059, A15 Austria and Flame verte.
Water heating
Solar water heater
The property benefits from an efficient solar water heater that supplies about 85% of our annual hot water needs. When the weather needs a boost, an immersion heater in the tank brings water up to temperature in about 20 minutes.
The 180 litre tank is plenty of supply for a four person family.
Hot and cold water is supplied throughout the house, and while only cold water feeds the outdoor kitchen at present, there is easy access to a hot water pipe to complete the supply.
Exceptional natural fire resistance
Although the walls are constructed using straw bale, they are far removed from exposed or combustible straw. The straw is densely compressed within the wall and completely protected by substantial layers of natural lime plaster.
This combination has an impressive fire-performance record. Independent fire testing of lime-plastered straw bale wall systems has achieved Class B-s1.d0 under the European reaction-to-fire classification. This indicates very limited contribution to fire and very low smoke production.
Full-scale fire testing has also demonstrated fire resistance of up to 120-135 minutes for plastered straw bale wall assembly.
The house is encased in fire resistant lime-plaster, which was applied in three separate coats, each one approximately 10mm thick and allowed to dry thoroughly before the next coat was applied.
This is a reassuring example of how traditional, natural materials can provide an exceptionally safe and durable modern home.