EcoBuild: Solar Panel Angles

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There may be a problem with the current Silver Spray plans and the angles for the solar panels. The current plan is for the panels to be bolted onto the proposed flat roof at the back.

  • Solar panels should be south facing and between 20 and 60 degrees.
    • I’ve heard / read that the ideal angle for solar panels in Cornwall is for them to be at 30 degrees (and south facing).
    • Below 20 degrees panels don’t self-clean when it rains. Dirty panels are less efficient
    • The angle that solar panels are normally mounted on flat roofs is usually low to reduce the amout they can get grabbed by the wind and ripped off the roof !
    • It could just be that a framework for the panels is factored into the building so that there is no chance it can be ripped off by the wind.
    • Flat roof mounting systems for panels all seem to be at about 10 degrees, so that the gap between panels is around 38 cm, and so that their is reduced possible “wind load”
    • Current rear flat roof area is about 4.1 x 8m = approx 32.8 sq m. If panels are all flat, a 4kW system takes about 28 sq m. So will need to see how the space works out.
    • See http://www.bauder.co.uk/photovoltaics-and-rooflights/photovoltaic-energy/baudersolar/pv-modules – images below – gap between panels moves up to 1.36m from 0.38m as solar panel angle of tilt changes from 10 to 30 degrees. But see reasons below for wanting 20 degrees or more tilt.
    • The Energy Saving Trust matrix for PV angle of tilt and how much south facing, that suggests optimum is south facing and between 20 and 30 degrees tilt.

  • More vertical panels do better in the winter, when the sun is lower in the sky. You are more likley to want more hot water in the winter (for space heating) and more electricity generation (to power feed the air source heat pump). BUT only 10% of generation output will be in the winter, so best to angle the panels for max, over the year, output.

I ran figures through the Energy Saving Trust calculator for a few variations at the Silver Spray postcode location:

  • South slope, XLarge 4Kw, 90 degrees = 2,688 kWh pa
  • South slope, XLarge 4Kw, 60 degrees = 3,499 kWh pa
  • South slope, XLarge 4Kw, 50 degrees = 3,643 kWh pa
  • South slope, XLarge 4Kw, 40 degrees = 3,716 kWh pa
  • South slope, XLarge 4Kw, 30 degrees = 3,715 kWh pa
  • South slope, XLarge 4Kw, 20 degrees = 3,640 kWh pa
  • South slope, XLarge 4Kw, 10 degrees = 3,492 kWh pa
  • South slope, XLarge 4Kw, 0 degrees = 3,274 kWh pa

EcoBuild: Photovoltaic, PVT Vs PV or PT

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Photovoltaic Thermal:: EcoBuild Expo Update

At the Ecobuild expo, there were a LOT of companies who had photovoltaic elec or water heating systems.  Few were combined PVT (both electricity and heating water). So I started asking why. Speaking to those that make the panesl and installers / advisors the consistent reply was that the reduction in output of both systems was more than 50% down on what you’d get if each was stand alone. One company that produced PV and PT panels said that:

  • A PV panel could produce around 280 Watts  of elec, a PVT panel about 120 Watts
  • A PT panel over 200 (I think degrees) water, but only 40 degrees from PVT.

Yes, it’s still good to cool down PV panels, with ventilation, or even surrounding green roofing. But it seems that cooling them, by linking in pipes to generate hot water doesn’t work. It seems that the temp hot water panels work at is so high to be efficient, that takes out too much electricity production. Or you compromise the amount of hot water production by having the panels at a much lower temp. ie to be efficient they both operate at vastly different temperatures.

So that means looking at seperate systems for electricity production (PV), hot water productin (PT) and something for when the sun isn’t shining for hot water (for taps and heating).

 

EcoBuild: Air Source Heat Pumps

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Air Source Heat Pumps

The installers / advisors to projects that were speaking at the lectures for self builders were all very positive about air source heat pumps in terms of how they work and how they stack up from an environmental / energy / sustainable point of view.

There are now automated systems for (for example) an air source heat pump to kick in when Photo Voltaic (PV) panels are producing more electricity than the house is using, and so at those times top up the water thermal store in the building. This can then be used for hot water or heating (under floor works at lower temps) at other times (if needed).

EcoBuild: Waste Water / Drain Water / Shower, Heat Recovery

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At Passivhaus levels of energy efficiency hot water accounts for more energy than space heating.

At last weeks Ecobuild, I saw a couple of systems that do this. They capture the heat from hot water that is going down the drain and feed it back into the hot water system. It seems there are 2 systems:

  1. A vertical pipe that the hot water flows down, usually slowed, around the cold water mains supply. Their is heat exchange from the waste water to the cold water, that, in these systems typically, feeds into the water heater / hot water tank.

  2. A system linked to just the shower. So that the heat in the shower waste is immediately put back into the shower. As most showers have a thermostatic valve, this means an instant and guaranteed gain.

+ & – Thoughts

Check the cost of the system Vs the predicted and probable saving for an evaluation of how long the system will take to pay for itself.

  • One of the 2 systems at Ecobuild was the, €299 retail price, system, that you can see at http://zypho.eu/english.html. So price wise, VERY worth considering,  but need to see if:
    • Have to use, what looked like, the integrated shower tray cap / valve bit, or can this work with any shower tray and it’s drainage inlet?
    • Will it cope with sand if used as the post surf outside shower?
    • What is the cost implication of this on each shower Vs a system that copes with multiple showers and other hot water drain pipes (bath, washing machine, dish washer).
    • Does it reduce the cold water pressure? (Does this matter ?)
      I’ve emailed Zypho these questions 
    • Nice write up on the Zypho unit at Ecobuild on the HardHouse blog by Mark.
      – looks good, but questions the heat exchanger and it isn’t yet fully UK approved.
  • Cost Implications:

If used for an external, post surfing, shower, will the system cope with sand, mud, dirt etc?
– it does look like the  Bristol based shower tray system could be put in post a sand trap !
– could even have this bit under the floor in the house and not outside where the cold, frosts etc. could be a problem. It could then also link in to the water outflow from the washing machine, dishwasher and any other ground water outflows of warm / hot water.
–  http://shower-save.com/Joomla_SS/pdfs/Adaptor%20to%2040mm%20for%20RT1-e.pdf
–  http://shower-save.com/pdfs/Recoh-Tray%20grey%20water%20heat%20recovery.pdf

 Per Shower Vertical Pipe
 + Point
  • More efficient as waste water heat put straight back into the shower being taken.
  • Could mean one system to grab the heat from hot water from multiple showers / baths / sinks / washing machines / dish washer etc.
  • Apparently more efficient, as the falling water naturally coats the sides of the pipe (not just the bottom)
 – Point
  • Does this reduce the shower pressure ?
  • Does the system cope fine with shower problems such as hair blocking them up ?
  • You could be sending warmed cold water to an already full heating system. eg You run a bath and by the time you empty the bath the tank has already re-filled itself.
  • Only works for waster water that is on the first floor so that it can flow down the vertical pipe. Seems to have been developed in the US where it can be fitted in the typically occurring basement water inflows.

It seems that if you could get a single whole house heat recovery system that auto feeds the cold water supply to showers, and if they aren’t being used sends the preheated cold water to the water boiler (if it’s not full) would be the best. See the schematic below from http://www.gfxtechnology.com/H-3.pdf

This is also how it’s been set up in the schematic at Bristol (UK) based  http://shower-save.com/
 – also see animation they have at http://content.wavin.com/WAXUK.NSF/pages/Certus-ShowerSave-Animation-EN/$FILE/ShowerSave.swf

UK Water Heat Recovery Supplier Listing:

Test Data for Recoh Units:

From http://shower-save.com/gastec.html

  • Recoh-vert 61.2% efficient, with a mixer shower
  • Recoh-tray is 46.9% efficient, with a mixer shower

Shower-Save is even more efficient with a low flow rate or electric shower:

  • Recoh-vert 64.0% efficient with electric or other low flowrate shower
  • Recoh-tray is 52.6% efficient with electric or other low flowrate shower

Schematics of Waste Water Heat Recovery Systems

Notes from other Websites re these systems:

From http://www.gfxtechnology.com/H-3.pdf:

  • Typically, 80–90 percent of the energy used to heat water in the home goes down the drain. Heat exchangers capture some of the heat in drain-water, allowing it to be reused by incoming water. One type, called a gravity film exchange drain-water heat recovery system, has been found to save 25–30 percent of total water-heating energy needed.
  • This technology is compatible with all types of water heating systems, but it is especially suitable with on-demand water heaters and solar thermal systems. Prices range from $300–400 and paybacks are in the range of 2.5 to 7 years, depending on how often it is used.

From http://www.renewability.com/power_pipe/index.html:

  • Falling film heat exchangers have been around for decades. Other than utilizing the “falling film” effect, however, the Power-Pipe® has little in common with other Drain Water Heat Recovery (DWHR) devices.
  • First generation units suffer from high water pressure loss in the freshwater supply, which causes flow problems. Second generation units resolve the pressure loss issue by adopting a non-counter flow heat exchanger design, which delivers a low heat transfer performance.

Other Water Heat Exchange Systems & Discussions:

From Earth Save Products (bottom of the page) their Heat Squirrel – 120ltr heat recovery vessel (for domestic waste water)
Heat Squirrel - schematic
Heat Squirrel - installed

Change Your Behaviour – Bath water heat recovery

One behavioural solution to waste water heat recovery, is to just leave a hot bath, hot sink of water full to cool down and transfer it’s heat to the room(s) before you pull the plug. How often do we pull the plug on a bath of hot water to let that heat head off down the drain, when we could let it cool down (ie heat the interior or the house) first ?

Life cycle of window materials – energy consumption and environmental impacts

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A great report by the School of Engineering at Napier University in Edinburgh on windows:

Frames of different materials have been assessed on the basis of their production, energy consumption and environmental impacts.

The investigation shows that aluminium and PVC frames exhibit large amounts of
environmental burdens. Accelerated ageing tests have been carried out to test the
durability of windows against weathering impacts. These tests show that aluminium clad timber windows are comparatively least affected by environmental impacts.

CONCLUSIONS (from the article)

  • Aluminium frames cause the highest burden to the environment because of the dangerous pollutants release and high energy consumption during aluminium production. PVC contributes large amounts of poisonous pollutants throughout its life cycle, while timber window frames have the least environmental burdens.
  • Embodied energy analysis has been carried out for a standard 1.2m × 1.2m window. Aluminium windows have the highest embodied energy, amounting to 6GJ. PVC, Al-clad timber and timber windows have embodied energy of 2980MJ, 1460MJ and 995MJ respectively.
  • All frame materials deteriorate to various degrees by environmental impacts. PVC is sensitive towards heat and UV radiation. Timber if not frequently treated, can easily be affected by environment. Aluminium, if not protected well by coatings, gets damaged under corrosive conditions especially in coastal and industrial areas. Al-clad frames are unlikely to deteriorate due to their protective coatings and appear to be the best choice from this point of view.
  • A survey analysis shows that aluminium and timber windows can easily last more than 40 years. Al-clad timber being new on the market, is expected to have a service life well over 40 years. PVC windows, in most cases, are reported to have an optimum service life of 25 years.

Scarlet Hotel inspiration

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Robert from ra-studio and myself went to the the The Scarlet Hotel,  for lunch to go over the plans progress and also to look at several aspects of the Scarlet Hotel that Robert had not seen.

As ever, a stunning lunch with amazing service and some more ideas / inspiration.

Some of which was reminding myself and showing Robert their smaller bedroom layout.

I also thought that we might consider having a central strip / floor corridor of wood from the entrance area, past and through the living area and kitchen, to the top of the 3 stairs down to the lounge. The current plan is slate or tiles for the entrance and living area (dinning, kitchen etc.) and wood for the lower living area.

I also like their stone work fire breast, but not sure this will work.

And good to see further Cornish wood cladding.

St Piran’s Day :: 5th of March

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It doesn’t take long for any Perranporth resident to learn about St Piran’s landing on Perranporth beach, on a mill stone, from Ireland.

The 5th of March has a feast of celebrations with great stories of the saint and other aspects of Cornish culture such as the flag.

“Legend tells us how Piran, who came from Ireland and was known there as Ciran’ (the Cornish language naturally mutates the first letter to a softer P’), was cast to sea tied to a millstone on the order of the Irish King who was suspicious of Piran’s miraculous powers.

The stormy seas calmed for the would-be martyr as he floated on the millstone to Perranporth beach.”

Perranporth beach at low and high tide

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Some great photos of Perranporth beach at low and high tide by Michael Marten in the Guardian on Saturday.

Perranporth, Cornwall. 29 and 30 August 2007. Low water 12 noon, high water 8pm

Perranporth, Cornwall. 28 and 29 August 2007. High water 6pm, low water 11.20am

Utility, shower and plant room

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The idea is that in addition to a downstairs loo and room for shoes and coats, there will be a room for the washing machine, that also has in it a shower, sink, drying rack, and probably screened off, the “plant”.

The plant elements aren’t foliage etc. but the large bits of machinery for the house such as the hot water tank, Mechanical Ventilation with Heat Recovery (MVHR) unit etc.

So, not a lot more on this at the moment, but spotted this photo, that could be a start of this room. ie put the washing machine in a cupboard ?

Waikiki Chic contemporary bathroom

Components:

  • Washing machine
  • Shower
  • Hot water tank
  • MVHR unit
  • Sink
  • Drying area – potentially with a drip tray, as it will probably include wetsuits etc.

It’d make sense to look over the photos etc. for the coats, shoes etc. room.

Not a fan of this look and feel, but the storage looks good for the utility plant room.

traditional-laundry-room

The idea below of an over the washing machines hanging rail could work well. But there also needs to be some full height hanging for wetsuits to dry.

over the washing machines hanging rail

hand rail could be elsewhere:

hanging rail

Washer and dryer platforms. The laundry room below puts the washer and dryer on a pedestal. I’m not having a drying machine, but it might be good to put the washing machine on a slight pedestal.

washing machine raised

Utility room sink to rinse wetsuits etc.

Also some counter top space.

The plant utility room might have extra space for the recycling (there will be some in the kitchen units).

IMG_1335