user3597: Vastu shastra (vāstu śāstra) is "a traditional Hindu system of architecture".
Did Lord Buddha debunk vasthu shastra? If not, what are some teachings made by Lord Buddha on the same? If Buddhism does not have an opinion on the topic, opinions of members are appreciated

user-1: Did Lord Buddha debunk vasthu shastra? 
Vastu Shashtra is set of instructions on how to build your house or buildings, it has nothing to do with anything the Buddha dealt with,  the Buddha lived in open air and if at all anything was built for Him, the Buddha was gifted parks for His monks, so I don't know if He would have directly addressed anything from Vastu Shastra as much as He would have addressed about 'Hemaghna' (Metallurgy). So there is nothing to be debunked, it's not a theory. 
If not, what are some teachings made by Lord Buddha on the same?
But if Buddha had to give advice about all the claims that Vastu Shashtra I believe Buddha would have given the same advise as he gave to the Kalamas.  

"So, as I said, Kalamas: 'Don't go by reports, by legends, by
  traditions, by scripture, by logical conjecture, by inference, by
  analogies, by agreement through pondering views, by probability, or by
  the thought, "This contemplative is our teacher." When you know for
  yourselves that, "These qualities are unskillful; these qualities are
  blameworthy; these qualities are criticized by the wise; these
  qualities, when adopted & carried out, lead to harm & to suffering" —
  then you should abandon them.' Thus was it said. And in reference to
  this was it said.
"Now, Kalamas, don't go by reports, by legends, by traditions, by
  scripture, by logical conjecture, by inference, by analogies, by
  agreement through pondering views, by probability, or by the thought,
  'This contemplative is our teacher.' When you know for yourselves
  that, 'These qualities are skillful; these qualities are blameless;
  these qualities are praised by the wise; these qualities, when adopted
  & carried out, lead to welfare & to happiness' — then you should enter
  & remain in them.
He told them to use common sense.

If Buddhism does not have an opinion on the topic, opinions of members are appreciated
It is a bogus pseudoscience, if at all of any value it's just of some aesthetic value to build temples. 
For e.g. according to VS the main door of the house should always be facing towards north direction to bring prosperity and all the positive things to house, now if that would have been case it should have been valid all over the world, then all the houses in the US and Europe who are not having north facing front door should have been relatively poor and all houses in India with such a door should have been relatively rich. But such is not the case. If it would have been the case, such kind of statistical data would have been available by now.
Besides the use of the terms like positive energy is very meaningless. So, if not by Buddha, it can be debunked by any high schooler. 

user8632: Vatthu-vijja is the pali equivalent of Vastu-vidya (or shastra) and, as mentioned above, refers to “architecture” as both science and a means of livelihood. It is well-known that in ancient India numerous ‘guilds’ of various crafts and arts exists. They travelled around the country, and possibly the world, in order to distribute and provide their skills and services. One type of such guilds was the builders guild, specialised in temple architecture and city planning.
In the context of Buddhism, Vatthu-vijja occurs in a couple of Suttas. Note: these sources all apply to Theravada Buddhism.
First, in the Brahma-Jāla Sutta (chapter 1) vatthuvijja is mentioned in a lengthy list of ‘wrong means of livelihood’ applicable to Brahmans that are ‘living on food provided by the faithful’:

...
(16) Looking at the knuckles, &c., and, after muttering a charm,
divining whether a man is well born or lucky or not.
(17) Determining whether the site, for a proposed house or pleasance, is lucky or not.
(18) Advising on customary law.
...
(source)

In his notes, the translator T. W. Rhys Davids says:

Vatthu-vijjā [...] The craft is further explained by Buddhaghosa in his comment on the Mahā-parinibbāna Sutta I, 26. Its success depended on the belief that the sites were haunted by spirits.
(source)

Upon looking at Buddhaghosa’s commentary on the above-mentioned chapter of the Mahaparinibbana Sutta, we find the following:

At that time Sunidha and Vassakāra, the chief ministers of Māgadha, were building a fortress at Pāṭaligāma to repel the Vajjians, and there were many deities who inhabited the area.
Now, wherever a place is occupied by powerful deities, they bend the minds of the most powerful kings and ministers to build dwelling-places there, and deities of middling and inferior power bend in a similar way the minds of middling or inferior kings and ministers.
The Blessed One, with his divine eye, surpassing the vision of ordinary men, saw those deities occupying Pāṭaligāma. He rose early in the morning, saying to Ānanda: “Who is it then, Ānanda, who is building a fortress at Pāṭaligāma?”
“Sunidha and Vassakāra, Venerable sir, the chief ministers of Māgadha, are building a fortress there to keep back the Vajjians.”
“They act, Ānanda, as if they had consulted with the gods of Tāvatiṃsa.
[Telling him what he had seen, and of the influence the deities, he added]:
“Among the famous residences of the Noble Ones, and as far as trade extends, this will become the chief city of Pāṭaliputta, a centre for trade. However, three dangers will affect Pāṭaliputta: fire, flood, and internal dissension.”
(source: page 25)

So there you go, Vastu-shastra was a common concept in Buddhism. At the very least, the profession and purpose of architecture (vastu) was known to the Buddhist authors.

user471: The Indian Vasthu Shastra and the Chinese Feng Shui are known as geomancy in English.
In DN 2, this is known as "vatthuvijjā" in Pali, which in Sanskrit is presumably, "vasthuvidya" or, knowledge or science of vasthu (the science of building sites).
The Buddha forbade monks from practising geomancy in DN 2 (translated by Thanissaro Bhikkhu), calling it an "animal art" or "debased art":

"Whereas some contemplatives & brahmans, living off food given in
  faith, maintain themselves by wrong livelihood, by such "animal"
  arts as: reading marks on the limbs [e.g., palmistry]; reading omens
  and signs; interpreting celestial events [falling stars, comets];
  interpreting dreams; reading features of the body [e.g., phrenology];
  reading marks on cloth gnawed by mice; offering fire oblations,
  oblations from a ladle, oblations of husks, rice powder, rice grains,
  ghee, and oil; offering oblations from the mouth; offering
  blood-sacrifices; making predictions based on the fingertips;
  geomancy; making predictions for state officials; laying demons in a cemetery; placing spells on spirits; earth-skills [divining water
  and gems?]; snake-skills, poison-skills, scorpion-skills, rat-skills,
  bird-skills, crow-skills; predicting life spans; giving protective
  charms; casting horoscopes — he abstains from wrong livelihood, from
  "animal" arts such as these.

Another translation of DN 2 by Bhikkhu Bodhi:

“Whereas some recluses and brahmins, while living on the food offered
  by the faithful, earn their living by a wrong means of livelihood, by
  such debased arts as:

prophesying long life, prosperity etc., or the reverse, from the marks on a person’s limbs, hands, feet, etc.;
divining by means of omens and signs;
making auguries on the basis of thunderbolts and celestial portents;
interpreting ominous dreams;
telling fortunes from marks on the body;
making auguries from the marks on cloth gnawed by mice;
offering fire oblations;
offering oblations from a ladle;
offering oblations of husks, rice powder, rice grains, ghee and oil to the gods;
offering oblations from the mouth;
offering blood-sacrifices to the gods;
making predictions based on the fingertips;
determining whether the site for a proposed house or garden is propitious or not;
making predictions for officers of state;
laying demons in a cemetery;
laying ghosts;
knowledge of charms to be pronounced by one living in an earthen house;
snake charming;
the poison craft, scorpion craft, rat craft, bird craft, crow craft;
foretelling the number of years that a man has to live;
reciting charms to give protection from arrows;
reciting charms to understand the language of animals

he abstains from such wrong means of livelihood, from such debased
  arts. This too pertains to his moral discipline.


3597: <p><a href="https://en.wikipedia.org/wiki/Vastu_shastra" rel="nofollow noreferrer">Vastu shastra</a> (<em>vāstu śāstra</em>) is "a traditional Hindu system of architecture".</p>

<p>Did Lord Buddha debunk vasthu shastra? If not, what are some teachings made by Lord Buddha on the same? If Buddhism does not have an opinion on the topic, opinions of members are appreciated</p>
 -1: <p><strong>Did Lord Buddha debunk vasthu shastra?</strong> 
Vastu Shashtra is set of instructions on how to build your house or buildings, it has nothing to do with anything the Buddha dealt with,  the Buddha lived in open air and if at all anything was built for Him, the Buddha was gifted parks for His monks, so I don't know if He would have directly addressed anything from Vastu Shastra as much as He would have addressed about '<em>Hemaghna</em>' (Metallurgy). So there is nothing to be debunked, it's not a theory. </p>

<p><strong>If not, what are some teachings made by Lord Buddha on the same?</strong></p>

<p>But if Buddha had to give advice about all the claims that Vastu Shashtra I believe Buddha would have given the same advise as he gave to the <a href="https://www.accesstoinsight.org/tipitaka/an/an03/an03.065.than.html" rel="nofollow noreferrer">Kalamas</a>.  </p>

<blockquote>
  <p>"So, as I said, Kalamas: 'Don't go by reports, by legends, by
  traditions, by scripture, by logical conjecture, by inference, by
  analogies, by agreement through pondering views, by probability, or by
  the thought, "This contemplative is our teacher." When you know for
  yourselves that, "These qualities are unskillful; these qualities are
  blameworthy; these qualities are criticized by the wise; these
  qualities, when adopted &amp; carried out, lead to harm &amp; to suffering" —
  then you should abandon them.' Thus was it said. And in reference to
  this was it said.</p>
  
  <p>"Now, Kalamas, don't go by reports, by legends, by traditions, by
  scripture, by logical conjecture, by inference, by analogies, by
  agreement through pondering views, by probability, or by the thought,
  'This contemplative is our teacher.' When you know for yourselves
  that, 'These qualities are skillful; these qualities are blameless;
  these qualities are praised by the wise; these qualities, when adopted
  &amp; carried out, lead to welfare &amp; to happiness' — then you should enter
  &amp; remain in them.</p>
  
  <p><strong>He told them to use common sense.</strong></p>
</blockquote>

<p><strong>If Buddhism does not have an opinion on the topic, opinions of members are appreciated</strong></p>

<p>It is a <strong>bogus pseudoscience</strong>, if at all of any value it's just of some aesthetic value to build temples. </p>

<p>For e.g. according to VS the main door of the house should always be facing towards north direction to bring prosperity and all the positive things to house, now if that would have been case it should have been valid all over the world, then all the houses in the US and Europe who are not having north facing front door should have been relatively poor and all houses in India with such a door should have been relatively rich. But such is not the case. If it would have been the case, such kind of statistical data would have been available by now.</p>

<p>Besides the use of the terms like positive energy is very meaningless. So, if not by Buddha, it can be debunked by any high schooler. </p>
 8632: <p>Vatthu-vijja is the pali equivalent of Vastu-vidya (or shastra) and, as mentioned above, refers to “architecture” as both science and a means of livelihood. It is well-known that in ancient India numerous ‘guilds’ of various crafts and arts exists. They travelled around the country, and possibly the world, in order to distribute and provide their skills and services. One type of such guilds was the builders guild, specialised in temple architecture and city planning.</p>
<p>In the context of Buddhism, Vatthu-vijja occurs in a couple of Suttas. Note: these sources all apply to Theravada Buddhism.</p>
<p>First, in the Brahma-Jāla Sutta (chapter 1) <em>vatthuvijja</em> is mentioned in a lengthy list of ‘wrong means of livelihood’ applicable to Brahmans that are ‘living on food provided by the faithful’:</p>
<blockquote>
<p>...<br>
(16) Looking at the knuckles, &amp;c., and, after muttering a charm,
divining whether a man is well born or lucky or not.<br>
<strong>(17) Determining whether the site, for a proposed house or pleasance, is lucky or not</strong>.<br>
(18) Advising on customary law.<br>
...<br>
<a href="https://www.wisdomlib.org/buddhism/book/the-brahmaj%C4%81la-sutta/d/doc52024.html#note-t-32275" rel="nofollow noreferrer">(source)</a></p>
</blockquote>
<p>In his notes, the translator T. W. Rhys Davids says:</p>
<blockquote>
<p>Vatthu-vijjā [...] The craft is further explained by Buddhaghosa in his comment on the <strong>Mahā-parinibbāna Sutta I, 26</strong>. Its success depended on the belief that the sites were haunted by spirits.<br>
<a href="https://www.wisdomlib.org/buddhism/book/the-brahmaj%C4%81la-sutta/d/doc52024.html#note-e-32275" rel="nofollow noreferrer">(source)</a></p>
</blockquote>
<p>Upon looking at Buddhaghosa’s commentary on the above-mentioned chapter of the Mahaparinibbana Sutta, we find the following:</p>
<blockquote>
<p>At that time Sunidha and Vassakāra, the chief ministers of Māgadha, <strong>were building a fortress at Pāṭaligāma to repel the Vajjians</strong>, and there were many deities who inhabited the area.<br></p>
<p>Now, <strong>wherever a place is occupied by powerful deities, they bend the minds of the most powerful kings and ministers to build dwelling-places there</strong>, and deities of middling and inferior power bend in a similar way the minds of middling or inferior kings and ministers.<br></p>
<p>The Blessed One, with his divine eye, surpassing the vision of ordinary men, saw those deities occupying Pāṭaligāma. He rose early in the morning, saying to Ānanda: “Who is it then, Ānanda, who is building a fortress at Pāṭaligāma?”</p>
<p>“Sunidha and Vassakāra, Venerable sir, <strong>the chief ministers of Māgadha, are building a fortress there to keep back the Vajjians</strong>.”</p>
<p>“They act, Ānanda, as if they had consulted with the gods of Tāvatiṃsa.</p>
<p>[Telling him what he had seen, and of the influence the deities, he added]:</p>
<p>“Among the famous residences of the Noble Ones, and as far as trade extends, this will become the chief city of Pāṭaliputta, a centre for trade. However, three dangers will affect Pāṭaliputta: fire, flood, and internal dissension.”</p>
<p><a href="http://www.aimwell.org/An%20Exposition%20of%20the%20Mahaparinibbana%20Sutta.pdf" rel="nofollow noreferrer">(source: page 25)</a></p>
</blockquote>
<p>So there you go, Vastu-shastra was a common concept in Buddhism. At the very least, the profession and purpose of architecture (vastu) was known to the Buddhist authors.</p>
 471: <p>The Indian Vasthu Shastra and the Chinese Feng Shui are known as geomancy in English.</p>

<p>In DN 2, this is known as "<a href="https://www.wisdomlib.org/definition/vatthuvijja#pali" rel="nofollow noreferrer">vatthuvijjā</a>" in Pali, which in Sanskrit is presumably, "vasthuvidya" or, knowledge or science of vasthu (the science of building sites).</p>

<p>The Buddha forbade monks from practising geomancy in <a href="https://www.accesstoinsight.org/tipitaka/dn/dn.02.0.than.html" rel="nofollow noreferrer">DN 2</a> (translated by Thanissaro Bhikkhu), calling it an "animal art" or "debased art":</p>

<blockquote>
  <p>"Whereas some contemplatives &amp; brahmans, living off food given in
  faith, maintain themselves by wrong livelihood, by such <strong>"animal"
  arts</strong> as: reading marks on the limbs [e.g., palmistry]; reading omens
  and signs; interpreting celestial events [falling stars, comets];
  interpreting dreams; reading features of the body [e.g., phrenology];
  reading marks on cloth gnawed by mice; offering fire oblations,
  oblations from a ladle, oblations of husks, rice powder, rice grains,
  ghee, and oil; offering oblations from the mouth; offering
  blood-sacrifices; making predictions based on the fingertips;
  <strong>geomancy</strong>; making predictions for state officials; laying demons in a cemetery; placing spells on spirits; earth-skills [divining water
  and gems?]; snake-skills, poison-skills, scorpion-skills, rat-skills,
  bird-skills, crow-skills; predicting life spans; giving protective
  charms; casting horoscopes — <strong>he abstains from wrong livelihood, from
  "animal" arts such as these</strong>.</p>
</blockquote>

<p><a href="https://suttacentral.net/dn2/en/bodhi" rel="nofollow noreferrer">Another translation</a> of DN 2 by Bhikkhu Bodhi:</p>

<blockquote>
  <p>“Whereas some recluses and brahmins, while living on the food offered
  by the faithful, earn their living by a wrong means of livelihood, by
  such <strong>debased arts</strong> as:</p>
  
  <ul>
  <li>prophesying long life, prosperity etc., or the reverse, from the marks on a person’s limbs, hands, feet, etc.;</li>
  <li>divining by means of omens and signs;</li>
  <li>making auguries on the basis of thunderbolts and celestial portents;</li>
  <li>interpreting ominous dreams;</li>
  <li>telling fortunes from marks on the body;</li>
  <li>making auguries from the marks on cloth gnawed by mice;</li>
  <li>offering fire oblations;</li>
  <li>offering oblations from a ladle;</li>
  <li>offering oblations of husks, rice powder, rice grains, ghee and oil to the gods;</li>
  <li>offering oblations from the mouth;</li>
  <li>offering blood-sacrifices to the gods;</li>
  <li>making predictions based on the fingertips;</li>
  <li><strong>determining whether the site for a proposed house or garden is propitious or not;</strong></li>
  <li>making predictions for officers of state;</li>
  <li>laying demons in a cemetery;</li>
  <li>laying ghosts;</li>
  <li>knowledge of charms to be pronounced by one living in an earthen house;</li>
  <li>snake charming;</li>
  <li>the poison craft, scorpion craft, rat craft, bird craft, crow craft;</li>
  <li>foretelling the number of years that a man has to live;</li>
  <li>reciting charms to give protection from arrows;</li>
  <li>reciting charms to understand the language of animals</li>
  </ul>
  
  <p><strong>he abstains from such wrong means of livelihood, from such debased
  arts. This too pertains to his moral discipline.</strong></p>
</blockquote>
