Heating Vs Lower Bills As An Optimization Problem
As an economist I think of lower heating bills as an optimization problem. You want to maximize your comfort while minimizing what you spend to stay comfortable. How you approach this challenge depends very much on your living situation and how deep your pockets are.
In an ideal world our homes would have such good insulation from our bodies’ and appliances’ heat to keep us warm in winter. Of course life is never ideal, and the chances are you don’t live in a passivhaus. But that doesn’t mean you can’t make the most of what you’ve got!
Most advice I’ve seen about cutting your heating bills tend to be a list of things you can do cut energy use. In this guide I’m going to lay down practical advice for cutting your heating bills this winter. I’ll start with the best option for tenants, then home owners and finally look at a third category of home lovers.
The Tenant’s Guide To Lower Heating Bills
Years ago I rented a cold and damp basement flat in London. It was an error from the minute I signed the lease. London is dark enough if live in a penthouse so below ground is just horrid. On top of this indignity the house was cold and a little damp. In particular there was a sash window with a lot of damage. You could fit your hand though the corner when it was closed.
If this had been my house I would have fixed that window. As a tenant my best bet was piece of £5 piece of window film. Now if you tell a passivhaus engineer you’re using window film as secondary glazing they’ll laugh themselves silly. But as a tenant with a terrible window and crappy landlord it was a super solution. It cut my heating costs and making my living room much more comfortable.
Tenants Are Not Incentivized To Make Fundamental Improvements
As a tenant you’ve got very little incentive to invest in improving someone else’s home. So your best bet are simple, allowable solutions. Focus your attention on taking better control of your heating.
I’m going to give you three strategies you can use to reduce the amount of energy your heating system uses. None of them are ideal, but a mix of the three will save you money with a limited impact on your comfort.
1. Turn down your thermostat
There’s a saying that if you reduce your thermostat setting by 1°C (1.8°F) will cut your heating bill by 10%.
That’s a ballpark figure, but there is actually some solid science behind it. A home loses heat in two ways. Heat leaves through the walls, floor, roof, windows. Heat also leaves through ventilation when hot air squeezes through gaps under doors and out windows. Both conduction and ventilation losses are a function of the difference between internal and external temperatures. That difference is measured in what are called heating degree days.
Heating degree days are a measure of the difference your heating system needs to generate between the interior and exterior temperatures. Heating degree days are calculated by the following procedure:
- Subtract the average of a day’s high and low temperatures from 65.
- Subtract each half-hourly temperature reading from 65, with the provision that negative values be set to zero, then sum the result and divide by 48 (48 half-hours in a day).
And for every 1°C (1.8°F) you reduce the internal temperature of a building, the number of heating degree days fall by around 10% (see below)
No, I’ll admit that this is not my ideal solution, because it involves tolerating a colder house. But its worth getting your head around. If you want an example of someone taking this seriously and slashing their energy use check out David King’s Sustainable Energy Without the Hot Air.
2. Time your heating wisely
The key thing to remember about heating is that you only need rooms to be warm at certain times of the day. If where you live has superb insulation then you can maintain a steady temperature throughout the day at low cost, but if the insulation is poor you need to get smart with the controls.
The graph below gives an idea of how someone who works in an office might program their home heating during the week.
Allow your home to cool down when you are asleep and at work. You will reduce the heat loss and hence the bill. The key to getting this right is to ensure that things are timed well. When you wake up or return home it shouldn’t be to a cold house.
3. Zone your home sensibly
Just like you don’t need heat equally throughout the day you also have different needs in different rooms. For example it’s quite nice to have a warm bathroom and living room, but bedrooms, hallways or dining rooms might not need to be warm.
In my home we achieve this with thermostatic radiator valves that regulate how hard each radiator works. But there are also really high tech controls these days like the Honeywell below, or there is always the old school method of just turning of the heaters in certain spaces.
As a tenant taking tight control of how much, when and where you heat is about your best option. Throwing on an extra piece of clothing or cuddling up to a loved one are always a decent option too.
If you are lucky enough to own your own home these tactics remain useful, but you can also work to improve the fabric of your home, as well as its heating system.
The Homeowner’s Guide To Lower Heating Bills
One of the hilarious things about owning a home is the realization that you could just get drunk one night and paint a huge mural on your living room wall. For some reason this desire quickly subsides and people end up painting everything magnolia.
The point being, if you’re lucky enough to own your own home you’ve got a lot more options. In this section we are going to look at the cost effective improvements you can make to a house. This is a bit of a piecemeal approach, but handy if you are on a budget.
1. Use a cheap fuel source
It bothers me a lot when I see people buying electric heaters during a cold snap. That’s because people are largely clueless about how expensive electric heating is. And sometimes they could be heating a house for the money they’ll spend heating a room.
This graph below show’s how expensive a unit of usable heat is in the US.
As you can see, both electricity and heating oil are expensive relative to natural gas. For slightly newer data the EIA provides a spreadsheet American’s can use for comparison. The situation is very much the same in the UK, with electricity costing three times as much as gas.
Finally, even if you decide to go with a particular heating technology, you have many manufacturers to choose from. We review the Carrier High Efficiency Furnace and the Coleman Electric Furnace as two examples from different ends of the efficiency spectrum.
2. Insulate, insulate, insulate
When you improve your home’s insulation you ensure that you get more comfort for every unit of heat you pump into it. In many cases insulation can be a superb investment, paying itself back in saved energy in a matter of years.
Of course this isn’t always the case. The graph below shows you how diverse the payback rate can be between different insulation technologies.
These examples are based on technology prices, building standards and energy costs in the UK. Don’t take them too literally for your own situation. What they do show is why governments are so keen of loft insulation, cavity insulation and draught proofing. This is also handy information to have when someone tries to sell you windows. Salesman talk a lot of rubbish about the payback on windows.
We don’t review specific brands of insulation much on this site. One of the few that we do is Icynene insulation that comes out of a company in Canada. But perhaps the industry needs to reinvent itself and give more choices to consumers.
3. Upgrade an ageing heating system
Personally, I only think you should turn your attention to upgrading your heating system when you’ve already had a decent go at improving the fabric of the building. By that I mean you’ve made all the cost effective improvements to insulation and draught proofing that make sense.
Where I live in the UK a new boiler pays itself back in around 10 years, depending on what you’re switching from. So it makes most sense to switch if you are facing a hefty repair or if your old boiler is really inefficient.
One of the main problems people face in this situation is underestimating the full cost of a new heating system. The graph below is data I put together for an energy company in the UK. It gives you a rough idea of how to price the full cost of the equipment, installation labour and extras.
Looking at each technology option in isolation is often how people think about insulation, draught proofing and heating. This makes sense for people on a budget.
But if you love your home and intend to stay a little while you might want to upgrade how you think about heating bills.
The Homelover’s Guide To Lower Heating Bills
Oscar Wilde once said that “a cynic is a man who knows the price of everything, and the value of nothing.”
Up until now we’ve taken a rather a cynical approach to heating bills. We’ve focussed very much on what you can do to cut them. We paid little attention to the value of a comfortable home. But there is another way to think about this.
Take one step inside a super insulated passivhaus in winter and you’ll get it.
Comfort is an important consideration
A house that is draught free, has no cold spots, doesn’t overheat and maintains constantly fresh air is truly valuable. And though you might never live in a passivhaus this everyone who loves their home should think about heating. If you make investments in the building envelope of your home, or its heating system, that improve your comfort, then any reduction in heating bills is a bonus.
So what’s a passivhaus you ask? A passive house (passivhaus) is a super insulated energy efficient home. It is built using ultra high specification insulation, triple glazed windows that face the equator to maximize solar gains, and is so air tight it uses a ventilation system to keep the air fresh. It needs just 15 kWh/m2a of heating, much of which can be gained from heat recovery in the ventilation system.
To give you some perspective this is a tenth of the heating needs of a typical modern home. Such a large cut reduces bills to almost nothing.
Picture is from the Hudson Passive Project, made by the architects BarlisWedlick Architects LLC.
Now I must say I really love that graphic. It reminds people that the heating demand of a home is just a function of how much heat it leaks. But for a lot of people it’s just a bit too much science.
Now certain people get very excited achieving a passive house certification, but its really just a standard. And you don’t have to meet the standard to have an incredibly comfortable home with low heating bills. But the way of thinking can really benefit everyone.
The fabric first approach encourages people to dig right down into air tightness, thermal bridging, U-values . . . and brings with it a requirement for high quality work. Even if you can afford to spend what is required for a top end retrofit, you can really benefit from an integrated way of thinking about things.
Bring In A Professional
If you’re serious about upgrading the comfort of your home then I’d suggest you get a professional. Serious energy efficiency require a whole lot of science and practical experience. It also means knowing tradespeople capable of providing quality work. You may be able to carry that off if you are really interested in the subject. For the rest of us, a pro is where its at.
The first step in this process is to have a serious energy audit done. This should involve a physical inspection of your property. The auditor will use tools like cameras, thermal imaging and blower door tests, and a software analysis of your home.
Here’s a checklist from the US Department of Energy about what to look for:
The big benefit of an energy assessment is that it gives you a baseline to gauge which improvements benefit you most. A full assessment will give you perspective about what your home’s strengths and weaknesses are.
A good energy assessor will then suggest some solutions that are sympathetic to your home and your budget. You should be under no obligation to do any work or feel locked into any particular company. Finding the right professional is half the challenge. So you should research if there is a certification or directory local to you.
After you have an assessment I always think its a good idea to take a breath before committing to too much work. If you are planning a few bits of work make sure they occur in a logical sequence. Time the proejcts so they don’t mess with your life too much.
But most of all don’t forget that a warm home is a valuable one. This does extend to the value of your home, but what I really mean is it can improve how you live. This is value that extends far beyond any heating bill.
Go to pretty passive houses to see passive houses that have been realized.
I founded Shrink That Footprint in November 2012, after a long period of research. For many years I have calculated, studied and worked with carbon footprints, and Shrink That Footprint is that interest come to life.
I have an Economics degree from UCL, have previously worked as an energy efficiency analyst at BNEF and continue to work as a strategy consultant at Maneas. I have consulted to numerous clients in energy and finance, as well as the World Economic Forum.
When I’m not crunching carbon footprints you’ll often find me helping my two year old son tend to the tomatoes, salad and peppers growing in our upcycled greenhouse.