Energy cost reduction Phase 1 complete!

💬 Lounge
41

If you're looking for a really big energy savings, about 8 years ago, I installed ground-source (geothermal) heat pumps from climateMaster. Products. They use about 1/2 - 1/3 the energy of typical residential EER 13 rated heat pumps.

They are a big initial install cost, but with tax incentives (30% federal in the US), and long-term energy savings, they eventually pay off. If you are in a state that also offers incentives, they become a "no brainer" if you need to update a HVAC system. In my case, I replaced multiple "old" heat pumps with a zoned system (you can actually install a system with fewer "tons" of heating / cooling than what is in your house now since these systems are less susceptible to efficiency falloff on very hot or very cold days (air-exchange home heat pumps must typically be oversized a bit to deal with this issue of greatly lowered efficiency as the temperature rises in the summer / drops in winter).

1 Like
42

I am absolutely looking at Heat Pumps!!

Hopefully you be able help with this…… having gone down that road.

GSHP requires about twice the sq footage of the house under heat, is what I am seeing.

The yard for my new house might, just have twice the sq footage, it will be close.

Also, heat pumps have a maximum heat of 45c. Uk gas/ oil fired central heating radiator systems run at 55-65c.

So either need to move to underfloor heating or upgrade radiators, also will need to use elec immersion heater for hot water to kill off the Legionnaire virus that survives at 45c.

That is very doable using solar, when I get it, a thermal boost during peak pv hours.

The balance in the Uk is going to be cost of elec for heating. At the moment I use about 100kWh per day for about 90 days (hugely variable day to day) of gas at 4.2p per kWh.

Elec today is 37.7p per kWh and will rise to 45p plus in April according to forecasts, and as the whole Ukraine conflict kicks in 50-60 p kWh by October is not unreasonable.

I am moving to a house that uses kerosene, and that is much cheaper than gas, so can see delaying the move to heat pump being delayed by several years.

I am looking at wind turbines in the yard to help with energy generation in the winter months when needed for heating.

Also investigating infra red localised heating.

At this stage, given the oil fired boiler does heating and hot water, is cheaper and less than 5 years old, I could see it being 10 years before I find a more cost effective way, but will keep looking.

BTW most UK houses don’t have the space for GSHP and have to use Air Sourced Heat Pumps, which I hope get significantly better before I need to look at them if GSHP is not possible (not sure yet what is below the grassed areas :persevere:

43

Not necessarily. There are a few ways to run the ground source ("loop") piping - Horizontal and Vertical are, I believe, the most common. The Horizontal layout does take a fairly large amount of space in your yard - that's probably what you saw. I did mine in a vertical layout - basically, a well drilling rig drills deep wells -- about 300 feet down - and the piping loops down to the bottom and back up. Usually 1 well for each ton of heating / cooling. Its pretty compact. Google for "geothermal heat pump horizontal versus vertical well"

Also, in the winter, the system tends to run the most at night when it is coldest. We use time-of-day metering and during the evenings (as well as all weekend, and holidays) its only about US$ 0.07 / kwh - makes for cheap heating / cooling.

44

Vertical is also preferred in cold climates where the frost line is deeper than is practical for a horizontal installation.

2 Likes
45

Vertical loops are insanely expensive in the UK, I'm currently working out the heating for a renovation in the Scottish Borders, 15th century stone building we've added a second floor to. Upstairs is super insulated, triple glazed and ground floor is 1m thick rubble stone walls, triple glazed to the north and double glazed on the south face for maximum solar gain. Utilising UFH loops downstairs with oversized cast iron rads upstairs.

Sadly, due to the prohibitive bore costs we've had to rule out GSHP. There are some interesting developments in the ASHP going on though so we're watching with interest.

Good thread. Also worth checking out the green building forums if you're working on a self build and looking for different approaches.

2 Likes
46

I did dis type of exercise just recently. In my case, just around 250W is being consumed by "standby" electronics (router, NAS, HE, all zigbee and wifi modules and similar devices). Because those are being needed, there is very limited way how to reduce this standard way. I do have small simple 1kwp single phase grid tied FVE plant on the roof of shelter. I did connect most of the constant power consuming device to this corresponding phase, including fridge, dishwasher, electric floor heating system, AC etc. taking into consideration max phase load capacity. This way, during the day, the majority of the solar energy produced is consumed by those devices and the limited rest is being passed to the grid. I’m able to use 60-70% of produced energy by this setup and also by optimizing devices running times, without the need of battery storage.
One day, in case of higher energy price (currently its around 0,14€/kwh) and more affordable battery storage, I will consider also bigger FVE setup with energy storage option, but nowadays its still not economical (battery lifetime vs accumulated energy savings).

1 Like
47

I am constantly amazed at how much we complain about energy prices in the US, while still enjoying cheap energy, compared to the rest of the world. We recently had an 80% increase in the supply portion of our electricity charges here in the state of Maine (US), driven by increases in the price of natural gas, which fuel about 70-80% of our electricity production in this region of the country. So, we're now paying just over $0.13 for supply and $0.09 for distribution (the two charges are split in much of the US), taking us to just over $0.22 per kwh, with very little use of time-based rates for most of the state (generally very rural).

People are losing their minds complaining, generally blaming government and the two local distribution utilities, neither of which are actually at fault in this case, at least for the immediate problem. Assuming things continue in Ukraine (very sadly) we can expect additional increases in the not distant future. I'm not at all happy about the increases either, but then I see the prices some folks here are paying, which are often double what we're paying. Makes our complaints a lot less significant, and makes me feel bad for many that visit here regularly. I figure your rates are our future rates, though, so we're designing the next house with a LOT of solar and efficiency in mind!

2 Likes
48

The whole western world is looking at an energy crisis.

It is a thorny issue and no one wants the solution deployed in their back yard, NIMBY

Successive governments in all countries have dodge the issue for decades and we let them.

Elec demand is going and elec generation is going down and we are running into the rubber hitting road period.

The UK has shut down the coal burning power stations, we have a lot of coal.

The North Sea bonanza has run its course and while having everyone on Gas fired central heating was great during the North Sea boom it leaves us stuck now.

Couple that with the UK has the worst insulated housing stock of all Europe which makes us even more heavy users.

Then add in the move away from fossil fuel vehicles to EVs - which have a battery which holds 6 times the daily elec usage of an average UK home.

And for fun throw in obsoleting Gas fired boilers by 2030 - so move everyone across to heat pumps, which use 3 to 5 times the daily elec consumption average.

The really big thorny issue is not baseline consumption but peak consumption and that is where the major costs are - using fossil fuels to bring power stations up fast to respond to demand.

So the response needs to be increase UK from 30% elec generated through wind power to 80% or put in Nuclear power stations. All of which no one wants near them.

So in the UK they did a big push to move everyone over to Smart Meters - they are actually very stupid and largely useless, but and one BIG but they do allow metering to the 30 min level.

This enables time of use tariffs, this will peak time charges to reflect real costs and also hopefully enable cheap energy overnight.

This will drive behavioural changes - washers/dryers/ baking storage radiators that can consume off peak energy, those that can afford it will buy expensive batteries or solar panels to offset usage, those well off will have to radically change the way they live to get cheaper energy.

It is going to get 'interesting' but we are facing a bumpy road ahead.

49

Found out something yesterday that will help.

The new car I have ordered is a ~78kWh EV expected in June - having an EV unlocks cheap energy at night 7.5p instead of 37.7p.

The car support V2L which means I can extract up to 2.2kWh from the battery in 240v and drop through an inverter to top up my batteries.

Kinda thinking of it as a failover/standby for high usage - house full of guests at Christmas / prolonged power outage.

So for the cost of a V2L cable and an inverter may be able to add an additional 70kWh to the house..

1 Like
50

Been working on energy management

Have historic Elec and Gas consumption, and projections for solar electricity generation at my new house for an 8kW array.

Working on a Heat Pump heating system delivering on the 300% advertised efficiency.

image
image1920×687 85.5 KB

Then you end up with something like this.

The yellow is 20kWh of daily battery at overnight cheap rate and 8kWh Solar array throughout the year +.

The energy gap becomes more obvious, to get enough solar to feed heating in winter months would require a tenfold increase of solar to 80kWh and I just don’t have that much space.

Looking at a 1kWh wind turbine will in my neighbourhood at 10m off the ground generate between 4-8kWh per day, so not really going to help, and to get a good 1kWh wind turbine operational is ~£4.5k.

A 10kWh one, I doubt I could get local planning to install .

So it looks like the next best bet is super insulation, ie thermal wrap house ~£5k and upgrade windows to triple glaze ~£30k (need to check this).

So looks like best approach is to reduce energy consumption over generate new energy.

51

We're finding much the same here in the US state of Maine. Our winters are long and can be very cold, and while our new mini split heat pumps are great during beginning of winter and early spring, they have a voracious appetite for electricity when the temperatures are near or below 0 F, which is common for us on many nights. One of the things we've noticed is that while they CAN provide heat at hose temperatures, they're not operating at anything near their touted 300-400% efficiency, and are much closer to 100%. We supplement with propane and even wood during those periods, although I haven't run tue calculations to see how much we're saving with the propane, and the wood is a giant, dirty PITA that I get tired of fooling with after a few days.

We're planning to build a new home in the next 2-3 years (purchased the land earlier this year, now waiting on material and labor shortages/prices to ease). When we do that, we'll focus on super insulating, but also on solar radiant heat (hydronic PEX tubing in floors and evacuated tubes to capture the sun's energy into large, heat-storing tanks). I don't know why more people don't do this, as it seems to be the most efficient way to make use of free energy for heating, and is far more efficient than photovoltaics when it comes to heating.

1 Like
52

I have been looking at the heat Pumps - hard.

Looks like Ground Sourced Heat pumps are more efficient.

It does appear the quoted efficiencies of Air Sourced Heat Pumps are based upon it not being too cold, so in the summer months you can get great efficiencies when heating the home but when it get cold, it gets less efficient down to a point where at -10 to -15c it now running at 100% - meaning you get 1kWh out for every 1kWh put in, and for most of the UK - when it it hits -5c gas Heating systems are using 100-150kWh per day.

Gas a year ago was 2.4p per kWh, it is now 10p per kWh and getting more and more expensive.

The cheapest I can get into a new contract now is 37.7p per kWh for elec.

So with a really cold spell -5c to -10c you are looking at £37.70 - ~£50 a day Heat Pump cost.

In all fairness it is rare to get those temperatures in the UK.

But however we heat houses going forward - it is going to get a lot more expensive.

So back to basics - reduce usage, that means super insulation.

Then, if you achieve that you have to look at house ventilation and that takes you into the realm of heat exchangers for fresh air supplies.

So as I remodel - looking at keeping the oil fired heating going as long as we can, while radically reducing the need for it by super insulation and using solar power for alternative heating when you both need heat and are generating enough.

Ultimately only using Oil fired heating for 8 weeks a year.

53

I live in a city that is very cold in the winter (Winnipeg, Canada), we also have hot summers. It is not unusual to have a few nights of -40 degrees Celsius (many nights of -30) during the winter and a few days of +40 degrees Celsius (many days of +30) during the summer. Air to Air heat pumps are by far more common here than ground source. Many suites in new multi-residential buildings (apartments, condos) would have their own air to air heat pump on the balcony, its almost the default way they build them these days. In my neck of the woods all these systems would have electrical resistive backup for when temps drop below minus -25. The heat pump itself would have a COP of around 1.5 at -25, a COP of around 2 at -20, a COP of around 2.5 at -15, and then going up fairly rapidly after that.

Around 80% of existing homes in, and around, my city would have a gas-fired high efficient furnace, and an electrical powered central air-conditioning unit, comprised of the condensing coil and compressor housed in a unit outside the house and an evaporative a-coil on the ductwork directly above the furnace.

Our current rates for energy are: 10 cents per kilowatt/hour (all taxes in) for electricity, and 45 cents per cubic/meter (all taxes in) for natural gas (4.3 cents per kWh). Our electrical rates should stay fairly stable over the next decade or two, we have an abundance of Hydro power, so much so we sell a lot of it to the United States. Our natural gas rates will go up, due to both the rising price of natural gas on the commodity markets along with our government imposing ever increasing taxes on carbon based fuels.

Reliability of utilities. This is no comparison. Natural gas supply in Canada (not Texas) is the most reliable utility there is. For 90% of homes they can expect not to have any unscheduled service interruption over the course of 50+ years. Electrical reliability typically has a few outages a year that are short lived. Longer outages of a day or more are possible and do happen to most homes at least once in a 20 year span.

Considering all of the above, there seems to be two common paths for homeowners in my area seeking energy efficiency, reliability, and environmental stewardship when it comes to heating and cooling their homes:

Replace Central Air Unit with Air to Air Heat Pump combined with a small/portable natural gas fired gen set and/or a V2L emergency power option. This is a fairly inexpensive option that costs an extra $2500 - $4500 dollars when replacing the outside air conditioning unit. This option reduces the yearly natural gas consumption by 40% - 75% (all depends on the severity of the winter), you can expect to have a 15% - 25% savings on your yearly heating/cooling costs. This option still results in greenhouse gas emission as you are still using significant amounts of natural gas. These savings increase as the price of natural gas goes up and the price of electricity remains stable. This option is very easy to make reliable in case of a power outage. Simply have a small gen set (like a 2000 watt Honda) run on natural gas to power your furnace, sump pump, fridge/freezer, etc... In this emergency mode you still have gas fired heat, but don't have the electrical supply to run cooling in the summer. These days some people are just using the V2L feature of their electric car to accomplish the same thing.

Replace Central Air Unit and Furnace with a Ground Source Heat Pump. This will cost you $30 000.00 dollars or more and is most often seen in new builds, rarely as an upgrade to an existing home. This option entirely eliminates the need for natural gas for heating of the home. Often, but not always, these homes have no natural gas supply at all. You can expect to have a 45%-55% savings on your yearly heating and cooling costs. These savings will increase as the cost of natural gas increases while the cost of electricity remains stable. It is more difficult to make this system reliable in the situation of an electrical outage. You typically don't have a small (or large) natural gas fired generator, and the V2L power options of many electrical vehicles would not supply the power required to run the heating/cooling system. Some new electric vehicles (like the F-150) would have no problem doing this, but it is not every electric vehicle. This option gets top marks for environmental stewardship as it allows the home to be a zero emitter of greenhouse gas.

Note my energy saving percentages listed above (15%-25% and 45%-55%) are directly correlated to my local price of both electricity (10 cents per kWh) and natural gas (4.3 cents per kWh). These percentages would be substantially different in a location where these rates are substantially different.

Probably, the number one reason why very few homeowners in my area are willing to ditch a gas-fired furnace is for the reliability during a severe weather event. At -40 degrees it is critical to keep your home heated, regardless of insulation level it will cool off fast at these temps. Natural gas supply is incredibly reliable, a modern high efficient gas furnace needs about 400 watts to run, an electrical requirement that is easily meet by an alternative when the electrical grid goes down.

4 Likes
54

If anyone is interested in calculating battery and solar savings, this video details a great online tool and takes into account the use of smart tariffs: Maximise Your Solar Investment: Choose the Right Solar, Battery & Tariff Option - YouTube