Five weather factors that affect your energy bills

The whole purpose of Degree-Day analysis is to adjust consumption expectations with respect to outside air temperature. So, if we subtract the "degree-day related" amount of consumption from the total consumption, we are left with the consumption that varies in a manner unrelated to temperature. It only takes a few minutes of reflection to realise that this is not the only significant weather factor.

The implication is that if we can "clear away" the temperature related variation, we can identify the other factors that may favourably or adversely affect your costs, addressing these may be important.

Let's think about some of these, but to make it more meaningful we will consider an extremely specific building for illustration purposes:

Our building is a draughty wooden-framed building with a lake to the south-east and a hill on the south west, woods to the north and a huge church due south that blocks midday sunlight, due south. Unusually for such a building it has large south facing glass frontage. The smart ones will have worked out that our building is somewhere in the northern hemisphere, so lets assume it is in Ontario (hey it can be anywhere we choose) so it is quite northern lying (which means that day lengths are very different in summer and winter).

Now let's consider some weather scenarios and see how the energy use might be affected in summer and winter.

Wind-speed and direction

A strong south-easterly warm wind (not uncommon) strikes the hill and it rains, dry air descends over the hill and is warmed as the atmosphere compresses it. This is the foehn , or chinook, Favonio, Garnoosh, Helny, or Helm wind. The effect is so marked that it has names all over the world - a simple change in wind direction can lift air temperatures locally by 20 Celsius in as short as half an hour. These are similar but not identical to dry deserts winds like the Santa Ana.

Cloud cover and Sunshine

On a clear night in winter or summer temperatures fall fast, and the morning is bright, the sun, rising in the south-east in spring and autumn, but hardly at all in winter, is low on the horizon and sun, both direct and reflected from the lake heats the glazed frontage. What was an overnight heating demand, suddenly becomes a cooling demand, until blocked by the church around noon. Controlling temperature is expensive. Planting shrubs low in the south-eastern garden might pay off !

Rain and Humidity

When it rains, heat loss is accelerated, but when it is dry and warm but humid, the cost of cooling increases.

Snow cover

Snow cover often reduces energy costs, it is a fantastic insulator, nature's own draft excluder and can shield roofs from extreme night-time cold.

Daylight hours

In winter there are long-nights, and in summer long evenings and bright mornings. The time of evening that darkness descends can be expected to affect both lighting costs and heating bills. If it does not, then there is scope for rationalisation !
With a high quality weather feed available, these can all be considered and the energy cost associated with them calculated. In many cases no clear causal relation may be apparent, in which case no action is required, but if one, or some combinations seem to be a big factor, and if some action is possible, it is as well to think about how to address it.

Free Degree Day Weather data service

HVAC energy view 20-20 Hindsight or 3D Blindsight

There are only three-dimensions required to build energy insight (or Building Energy Intelligence as it is often known), with these it is possible to look back (or forward) and understand energy use for heating or cooling with clarity. They are:
  1. Under what operational conditions do you use energy ?
  2. What effect does weather have on use?
  3. How much energy are you using ?
If data regarding these are missing or flawed, obviously any insight that you may believe you have gained cannot be trusted. The resolution of both metering and monitoring can also be too low to be useful or too high to be meaningful. It is really important that companies providing interpretation tools for looking at energy use understand these implications.

So assume the data that we do have is accurate, and consider the time resolution of the data. Lets suppose we have degree-days per week of heating load and weekly heating fuel consumption (BTW did you know we provide a free degree-days service)

Clearly, we can plot 52 plots on a years X-Y chart and get some pretty meaningful assessment of how weather and energy use relate.

Does it help to improve the energy consumption resolution to daily, well yes if we look at daily averages, we can see that (assuming our building is a normal office), that weekend use is lower than week-day use. But suppose that one weekend it isn't, we need to know if this is a short term problem or whether we are responding to weather at the weekend (which we should not be).

The only way to usefully distinguish the data, is to change our 52 plots of load and consumption into 365. We note that data (without insight looks less stable (but it is more cosnsitent and less erratic) - How can that be ?

If we switch off at weekends, weekend energy use will consistently be lower than weekday use. So variations of weather at the weekend will not be reflected in consumption (ignoring extremes of fabric protection).

 So our data becomes more consistent with operational expectations (less erratic), even though average variance is greater (because there is inherent diffence in the data that was “masked” by rounding up to whole weeks.

Now lets take this a step further, if we have energy say at hourly intervals we can look at weekly profiles. Weekends should be flat, and there will be optimum start patterns during boost periods (if we are treating core heat) but none, if we are ventilating. 

 SO depending on ventilation rate and hourly weather we see different patterns of consumption (degree-days are built from degree-hours).

To make meaningful understanding of energy recorded hour-by-hour or better, we need weather hour-by-hour or better, and with this we can get full information about operational schedules.

In general, operational schedules, weather and energy data, should be available at similar time resolution to allow creation of best insights.  Or alternatively, if you are missing any of the three, some aspect of your insight is blinkered and real considerations will be lumped together in broad-brush approximations that good energy management practice can  highlight as a mistake.

A note of caution – We can go too far... The theory behind degree-days assumes various factors (like that themal mass of a building is negligible and insulation is perfect) – these assumptions break down in short time periods (fluctuations in tempertaure are “buffered” by brickwork causing an exponentiola response).

Also some plant has long term harmonics (a boiler header takes time to heat and cool), this means that high frequency samples that include to much resolution must be averaged over repeated periods to retain meaning - but that is a subject for another day.

Read  a cool analogy  on energy management and waste  - how they are like spilling beer

Energy managers - know your inner hero

The relationships of an energy manager
A light-hearted view.

Disclosure - Massive personal bias - I like this diagram because it explains the problems our clients face each day. 

Would I go as far as to say energy managers are heroes ?  Well, yes because we are tasking them with the small job of saving the planet, the future for our grandchildren etc. - so how about we show them a modicum of respect ?
By the way you too can be a full-time energy manager ..
Look around you - find a control (you are a fully qualified light switch operator), consider your context (it's quite bright enough - thanks to sunny weather), you can tell your grandchildren you are saving the planet - your boss calls it corporate responsibility, it makes your accountant happy and who cares about the energy sales rep ! - So switch it off is a win, win,  win, win, win situation -
the only loser is big oil - HA !  
If you did switch off something here is a reward :  We can be heroes - David Bowie 
Lets take a look at a few of the trickier dialogues that may occur and see how they should be countered. 

Weather Forecaster :  The energy manager needs no excuse, ref Michael Fish BBC Classic

Conclusion : Weather is a great excuse if it is the real reason for energy expenditure, because short term, (apart from earnest prayer) there is little you can do about it - In the longer term, well documented cases can be made for insulation, etc. but it requires really good energy management to make a convincing case from the numbers

Accountant : The average cost for heating is X per square-foot per year so why is ours ....?
You: Our building maintenance budget is ... our boilers are ... old , I am not subscribed to we live in an Igloo on a mountain - Get a Grip man !

Conclusion: while the bean counters have no context, they can be a nuisance.  But they have power, so you had better be in a position to explain your role to them (the diagram above may help introduce the ideas) and you can make them your greatest ally.

Business manager : I expect 220 working days per year 08:00  -18:30 and I want comfort
You : "Yes - Ma'am" - alternative (less advisable)  retorts available at

A well documented set of service targets, occupancy scheduled and organised contextual data about your operations can go a long way to justifying your existence eg energy management of location

Engineer : I would like a ...
You : "Yup good idea - what will it cost, I will work out what it will save - lets do it !"

In short, anyone dealing with an energy manager that does not have the complete picture of their context and control (not billing, but energy use), is not in a position to comment. However, equally, the energy manager lives within a very complex "eco-system" .  With the right tools, he or she can ease the workload of a number of people that have contact with company operations.  Investment in good energy management tooling usually pays off both directly and with spin-off benefits.

Sorry that last comment was heading in the direction of a sales message - I better stop here.

What type of energy management fool are you ?

Building Stack, Macau
Building Stack, Macau (Photo credit: thewamphyri)
The other day I was asked how I would go about managing energy of a large portfolio of buildings. I didn't have a stock answer, which is crazy when you consider my job...

A few ideas quickly surfaced in my mind. I was immediately reminded of the characteristics of the many excellent (and fewer atrocious) energy managers that I have met. I believe all management styles have some redeeming features and all have occasional weakness.

I thought it might be useful for me to put a bit of thought in, write it down and share it - Here it is - I hope it is useful...

So this article is about how I see energy management styles. They are getting it right or screwing it up royally  but mostly it is a bit of both ...

Smart-Meters or Smart Users - what do we need?

A lot of nonsense has been talked about smart-meters -  some stretch the truth and others are remarkably honest - you must be the judge

 CenterPoint Energy’s smart meters and intelligent grid can significantly benefit the environment by reducing consumption of fossil fuel resources, thereby reducing emission of greenhouse gases (GHG) and other air pollutants. is straightforward:

 A smart meter itself won't save you money, but it may come with add-ons like an energy monitor or computer software that could.

Several things are clear:

It is said "a watched pot never boils" - studies have shown that watching energy use does not have this effect! However, someone who cares enough to watch energy use may be motivated enough to detect when waste occurs, be thereby more informed and take action.

Most energy is used by completely automated functions - eg thermostats and timeclocks.  These are completely insensible to price and so need to have "added smartness" if we are to benefit.

Such automated controls are general set to achieve an objective (to keep water hot) and not to do so efficiently (to keep water only so hot as is required).

Therefore clearly consumers as nascent energy managers benefit most when a pattern of waste can be observed.  The usual approach might be to document under what conditions energy consumption might be considered useful and when not.  THIS IS THE MISSING ELEMENT.

Let's take an example

A typical school, is occupied between 08:30 and 05:30 Monday - Friday during term-time.  Specific exceptions are notifiable (Parent teachers evening - 21:30, school play etc.)

Now if your "smart meter" does not know this pattern (and most don't because they are supplied by utility companies who have no knowledge of building use) then it is actually a meter, not a smart-meter.

The rate of use depends on weather and time of year, because energy is used for heating, lighting and possibly ventilation, and all energy is ultimately dissipated as heat (light bulbs are hot, efficient light bulbs are less hot),

So again if your smart-meter knows nothing about the weather, it cannot see what is waste and what is not.

So what is surely required is a tool to enable a "smart-person" to look at their circumstances and decide if the energy used under these circumstances can be justified.


Yes we need smart meters - but they are not smart - they provide data.

Yes we need weather data and building context and use case.

Finally to save energy we need to compare what is used, with what is needed - this is decisive as it distinguishes use from waste.

Energy Management, location.location & location ?

They say three things matter in marketing : location, location and location - which I think is an exercise in exaggeration.  However there are three ways in which location is utterly critical to energy management in buildings.

Geographic Location

This can be pretty precisely defined in terms of latitude and longitude and (since buildings sit on the surface of the earth) generally this defines altitude above sea level, which can be telling in terms of temperature, solar gain ( mist is very height sensitive), air pressure, wind speed and direction and so on. 

In short location determines weather on a global and local scale. And weather is why we heat and cool buildings ! - In fact weather is why we have buildings ! To quote from our weather provider meteoblue (we merge their data with client energy data)

High resolution means that there is always a meteoblue weather forecast close to you - closer than 2 km in Central Europe, closer than 8 km in all of Europe and North America, and closer than 11 km in Africa, South America, and Southeast Asia. Forecasts are further adapted to each location by meteoblue downscaling methods. meteoblue forecasts extend to 5-7 days, with hourly detail for every location. This detail is also available for the atmosphere, for the entire continent, and for the sea surface covered in the respective forecasting domain. 14-day forecasts are also available.

Naturally it helps if the location is neatly documented :

It seems with facilities as powerful as the Google Maps API to hand - a simple first stage for any energy manager is to document exactly where each of their properties is located.  They should be able to download on demand a list of exact co-ordinates.  This can be of assistance not only to the energy manager, but for all manner of services (delivery of materials A - B, client access "how to get here", operations etc), but as it is utterly critical to energy management, it is not optional in any half-adequate energy management suite.

Physical Location Context

As an energy manager it is not sufficient to know where a building is to be found - we have had one client "lose a tower block" - local government in Britain is not perfect :)  

An energy manager must also have an awareness and appreciation of significant local geography and topography. Two identical hotels (one in the middle of town, one on the north shore of a lake) are identically built - benchmark target performance is the same.  However, in winter after a clear night (cold) the sun rises low on the southern horizon and reflection in the lake gives a double dose of solar gain (hot).  So on cloudless mornings in winter, none building has higher cooling loads than the other continually shaded building! 

Where I live (near Brienz) the effect of Foehn winds is famous (also known by numerous other names locally - Chinook, Favonio, Garnoosh, Helny, Helm) - a simple change in wind direction can lift air temperatures locally by 20 Celsius in as short as half an hour.  These are similar but not identical to dry deserts winds like the Santa Ana.

An energy manager with no appreciation for physical weather vs. statistical weather has little chance of understanding some of the distortions that physical circumstance  can create (simply predominant wind direction or sea fogs can be significant).

Physical aspect

The third sense in which location is critical is the internal building location. Trapped heat rises, requiring de-stratification to keep the top and bottom of a building comfortable. Sun and shade effect different fa├žades at different times of day and year. Wind direction can play havoc with Air-handling equipment (how often does a warm outlet feed into an intake creating false chilling demand through unwitting air recirculation?

So - when a marketing man says it is about location, location and location - an energy manager can upstage him every time!

What is Wealth ? - The value of sufficient

Who wrote;

"Wealth that exceeds morality can be built - 
if daily bread for all is deemed dispensable." ?

Or - Why I think my Grandfather was a spy !

Read on to find out...

Yalta summit in February 1945 with (from left ...
Yalta summit in February 1945 with (from left to right) Winston Churchill, Franklin Roosevelt and Joseph Stalin. Also present are USSR Foreign Minister Vyacheslav Molotov (far left); Admiral of the Fleet Sir Andrew Cunningham, RN, Marshal of the RAF Sir Charles Portal, RAF, (both standing behind Churchill); Field Marshal Alan Brooke and Fleet Admiral William D. Leahy, USN, (standing behind Roosevelt). Note ornate carpets under the chairs. (Photo credit: Wikipedia)
Back in 1949 my grandfather David Ferguson wrote a book A measure of corn: the key to world economy  

This was at a time when the world economic system was at the point of collapse and nothing seemed reasonable as a replacement for the Gold Standard. 

He worked in various European economic research institutes in German, Italy, Belgium and Sweden between the world wars and foretold the inevitability of war with some clarity.

Some find it is fascinating to know a little of the background of an author, and in this case I think it is relevant. 

This grandfather of mine, who I never knew, was a Cambridge economist and pretty well connected to some bizarre & even famous historical characters.

Quoting from:
In 1937, Walter Johannes Stein published King Leopold‘s Plan in The Present Age, purportedly at the behest of Winston Churchill, and Stein and Eugen Kolisko travelled to Brussels to meet the King (Leopold III) at the home of Walter Morse Rummel. Stein and the King became close and it was decided that a Research Institute for World Economy would be set up in Brussels run by David Ferguson, a long standing colleague of Stein’s from his days working with Daniel Nicol Dunlop, and J K Montgomery from the Roman Agricultural Institute. 
In 1937, Leopold III visited London as part of a Peace Mission. 
In 1938, Prince Bernhard of the Netherlands invited Walter Johannes Stein to visit him to ‘discuss the new economics‘. Stein had been able to establish connections with politically authoritative personalities through his publishing activities, and he knew Winston Churchill and Roger Keyes,...
Roger Keyes‘s diary picks up the story:
After nightfall, an unexpected visitor, who proved to be an emissary from King Leopold arrived at … (Roger Keyes house in Chelsea)… and told him what the King wanted to know.”
I cannot establish the accuracy of these details beyond doubt, though I have cpies of letters from all the above who were communicating with my Grandfather. 

I know he was picked up by a British Naval battleship from the coast of Belgium during WWII departing on the personal instruction of King Leopold III  at the time of the German invasion of Belgium, this suggests at least that he had something interesting to say.

The "emissary" (who we cannot name with certainty)  communicated with both Churchill and Roosevelt and carried the plans for  Operation Sea Lion .  to the Allied powers in 1941.

My father (Ron) and Grandmother (Sarah) went to their deaths with their lips sealed on the subject - I suppose my grandfather may have been a courier of some importance. 

Exciting as speculation has been to me since I was a young boy, it is now clear from his memoires that my Grandfather saw the question of how we measure wealth as the key to world peace. 

He saw this as far more significant, than his role in either war so, further to Fred Wilson (a fascinating blogger who I greatly respect and who seems to explore the relationship between wealth and social good with some clarity) - here are some thoughts on sustainability, by a one-time world authority.

I hope we can learn the value of "sufficient".

David Ferguson argued that the ultimate scarcity in the human condition is "Our Daily Bread". He showed using available trade statistics that (until that point in history) wealth could only be stored (in a moral society)  to the extent that bread, corn or grain production exceeds necessity and could be warehoused.

Note that what is economic is not necessarily compatible with what serves humanity

 In those days we could not economically convert food-crops to ethanol for power. 

I can only think he would have been horrified, that we now can. This provides the opportunity to invert his observation and trade in life...

Wealth that exceeds morality can be built if daily bread for all is deemed dispensable.

By extension, the ultimate price that can be paid for energy is life - so if we are wanton with our use of energy we are surely guilty of waste, but if conducted as national or cultural policy, it is no less than warmongering.

I do not know if my grandfather would have accepted my deductions, I hope so.

I think it a fitting memorial to transcribe a poem (found amongst his papers, and we suppose by him) from the First World War trenches "Somewhere in France" - where he was a signaller.

Here he "caught the bullet" that lead to his death, decades later.  

He concluded his life with these words to my father: "Do not hate the man that shot me, rather the system that made him do it". 

I believe we must work to better the system...

Battle Echoes 
Somewhere in France - 1914

Over the top; - never a stop,-
Into a hail of shell;
Glaring wild skies,- blooded eyes,
 into the midst of hell.

Into the valley with a glorious rally, 
on with a maddening dash;
daring undaunted foemen flaunted, 
Over the wire they crash.

Front-line taken, enemy shaken,
onward again at a run;
bayonets crinching, enemy flinching, 
spitting out death from a gun,

Cursing and urging, wavering, surging,
Stabbing and fighting for life,
Screaming growling, snarling, howling 
in furious maniac strife.

enemy packing supports for attacking,
Men hanging up on the wire;
Shrieking and groaning, helpless, moaning,
 riddled and shredded by fire.

Old pals stopping, - dying, - dropping, 
twisted and torn, and still;
Writhing in pain, 'mogst the heaps of the slain,
Companies missing, howitzers hissing,
"Kill: Kill : KILL"

Wounded and dying, bleeding and crying;
Dead lying stiff where they fell.
Bloody and battered, tortured and tattered, Few will there be to tell.

Of what death stricken valley, the fierce, frenzied rally;
They who had loved love so well.
but HE above knows, they've won their repose They're promoted to Heaven from hell.

And deeply we pray, for the Dawn of the Day,
as sadly we turn o'er the sod.
For the End of the Night and the Gleam of the Light
Of the Spirit and City of God.

Rest In Peace
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