Space heating and cooling
PassivHaus purists would say that additional heating systems are unnecessary as the inherent design, high insulation and air-circulation provide all the heat one needs. I’m a ‘belt-and-braces’ chap, so prefer to have an alternative.
Conceptually and in the absence of detailed costing, it would seem that under-floor heating makes the most sense. It provides an even heat using low temperature water/ fluid. It also heats the fabric of the building, which means that the inherent heat-retention properties of the floor are used to best effect. The most commonly used method of heating out here is to reverse the air-conditioning units – efficient in terms of energy consumption to heat output but not sustainable for other than short-term occupation. It also gets expensive in the non-insulated draught-ridden buildings which are the norm – a friend told us that they pay €500 per month in electricity in winter mainly for space heating!
We also like the idea of a Kachelofen, as something cosy to sit near – and use the chimney to heat the upper floors, as well as additional input for water heating. On further thought, especially having lived for 3 winters with a wood-burning stove in the stone house, we’ve decided that a Kachelofen is too much hassle, and unnecessary in terms of heating anyway. Also expensive, though Anke will miss the ash for the garden.
Summer cooling is as important a factor as winter heating. Outside temperatures go above 40 in high summer, and are usually in the high 20s to middle 30s for most of the late Spring to early Autumn months. The Passive-On project deduced that natural air circulation could provide much of the temperature control in summer without the need for mechanical air-conditioning units. I have still to understand how one controls natural air-circulation – apart from opening or closing doors/ windows – in summer but avoids draughts in winter. The obvious solution is to reverse the under-floor heating to provide cooling (in which case, it is under-ceiling cooling).
Domestic Hot Water
Clearly one main system has to be solar heating. There is too much sun here to consider anything else. BUT, it does get cold and cloudy in winter. There are times when I have looked out at a dreich (guid Scots word) scene, with mist hanging over the mountains and a gentle dampness falling elsewhere. The winter 2009 – 2010 was the wettest the locals can remember, with almost non-stop rain from December to March. Even in April it was still cold and wet. Late November/ early December 2010 was also torrentially wet, with serious floods in Risan and Kotor, and even worse for villages along Lake Skadar. In comparison though, 2011 was exceptionally dry. Hardly any rain from May to November. Indeed the drought affected electricity production – heavily dependent on hydro-generation.
We will have to design a simple way of cleaning the solar panels on the roof to maintain their efficiency. We also need to have a heat sink to prevent the panels over-heating. This could be the water storage tanks.
Conventional systems here have electrically heated tanks close to the point of use – bathroom or kitchen. This can be extremely expensive, and will get more so as electricity increases in cost to that of western Europe (currently it is only about 10c per kWh).
If we have one central hot water tank, its location is very important to minimise pipe runs to the main points of use – main and guest bathroom as well as the kitchen.
In my past houses in UK, the cupboard with the hot water tank was also used to store sheets, towels &c, as it was always warm. Called an ‘airing cupboard’.
While there is wind here, as with everything in the Balkans it is glut or famine. When it is windy, it is extremely windy, but not that often. Anyway, even a vertical turbine takes up more room than we have available, plus the noise and aesthetics make objections from the neighbours a certainty.
Cost is the major factor here. We do not have enough area to install a ‘near-the surface’ system, so would have to drill through the rock (limestone). An estimate of €100 per metre for a minimum of 70metres deep per hole means a very careful analysis is needed. We haven’t got that far yet. Dušan tells us that we will have to have test holes drilled to find out what we need in terms of foundations. We are asking the obvious question: how much extra would it cost to install pipes for a future geo-thermal system, even if we don’t have it initially.
Anyway, there will need to be an air inlet pipe for the HVAC system, which we understand needs to be a minimum of 30m long and about 1 to 1,5m deep.
Provision of electricity
Electricity supply to Risan is weak, with variable voltage and irregular failures. There are power-cuts in winter as much as in the peak air-conditioner usage of the summer, especially when there is a serious storm. I would like to build in an uninterrupted power supply system (UPS), which will also give a constant voltage – allowing better operation of all electrical appliances.
UPS usually means batteries. The battery room needs therefore to have easy access for replacing batteries and general maintenance.
An UPS will also allow for the possibility of connecting PV solar panels in the future when these become more economic. Photo-voltaic might start to make sense if we were far from the grid, but we have the line crossing the property, with a connection into ‘Le Beton’. We will need to allow for cables from the roof to the Keller.
An alternative to a UPS when there is a power cut is a generator which cuts in either automatically or manually. Generators are noisy and smelly, also not very environmentally friendly. A generator also does not overcome the variability of the normal mains power supply. But I assume that it would be cheaper than UPS.
The minimum emergency supply should be enough to power the heating/ ventilation system (for 24 hours), lights (for 8 hours), computer equipment (for 12 hours), and one of either the main cooker, the washing machine or the clothes dryer (for 4 hours).
Any ideas out there gladly received!
LED seems the system for the future, with advantages of long life and low energy consumption. It also allows the possibility of ‘mood’ lighting changes. We need to consider wiring, installation and maintenance. Also cost compared to currently conventional systems.
Keeping records of energy use compared to inside and outside temperature will be a vital part of our wish to use the house as a demonstration building. A monitoring and data logging system needs to be built in. Some of this should be part of the heating control system anyway. As well as inside and outside temperature, energy used for heating/ cooling, we have to establish what other parameters need to be recorded; possibly inside and outside humidity; hours of sunshine (for solar panel performance). And whether all this can be centralised and automated.
© all text and photographs, except where individually credited to other sources: James Collins